Source: UNIVERSITY OF FLORIDA submitted to
ORNAMENTAL PLANT BREEDING AND CULTIVAR DEVELOPMENT
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1009385
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Mar 15, 2016
Project End Date
Mar 14, 2021
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
Gulf Coast Research and Education Center, Bradenton
Non Technical Summary
Ornamental plants are one of the largest agricultural commodity groups in Florida and many other states in the U.S. Caladium, gerbera, impatiens, lantana, ligustrum, and nandina are very important crops for the ornamental plant industry in Florida and other states. Severe diseases have been a substantial challenge to caladium, gerbera and impatiens growers; the invasive behaviors of lantana, ligustrum and nandina have posed another severe threat to the nursery and landscape industry. In caladium, Pythium root rot, reduces caladium plant growth and tuber yield as much as 70% and has become the main cause of poor plant quality in pot plant production and poor plant performance in the landscape. Another fungal disease, Fusarium tuber rot has caused a significant decline in tuber yield of many cultivars and made production of many important cultivars unprofitable. Bacterial blight, on the other hand, has been the most common foliar disease of caladium, reducing the marketability of potted plants as well as lower tuber yield of field-grown plants. In gerbera, powdery mildew can rapidly blight leaves, stems and flowers and has been the most common and severe disease for both growers and consumers. Impatiens is the most popular bedding plants in Florida and the nation as well as one of the top ornamental plant crops in Florida and many other states. Impatiens downy mildew (DM) incited by Plasmopara obducens has caused a great concern in Florida and many other states and countries. Regional outbreaks of DM have decimated the impatiens production and landscape use in Florida and other states. The invasive behaviors of Lantana camara, Ligustrum sinense, and Nandina domestica have resulted in the risk of them being banned from propagation, production and utilization. On the national level, invasive plants invade more than 100 million acres of public and private lands and natural areas and are causing a $13 billion loss per year to the economy. The main goal of this project is to develop new cultivars with enhanced disease resistance or reduced or eliminated invasive behaviors. The availability and use of disease- resistant cultivars can help growers reduce pesticide use, lower production costs, improve crop productivity and quality, and enhance plant performance. The availability of non-invasive cultivars can provide the industry with a ready substitute to the invasive forms for continued propagation and production of these popular plants. Additionally, this project aims to develop and apply molecular markers, genetic linkage maps, and transgenic techniques for enhancing disease resistance in gerbera and impatiens. The availability of these tools should facilitate the cultivar development process in these and other ornamental crops.
Animal Health Component
90%
Research Effort Categories
Basic
10%
Applied
90%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2012120108120%
2012110108120%
2022122108130%
2022123108130%
Knowledge Area
201 - Plant Genome, Genetics, and Genetic Mechanisms; 202 - Plant Genetic Resources;

Subject Of Investigation
2110 - Ornamental trees and shrubs; 2123 - Bedding/garden plants; 2120 - Herbaceous perennials and decorative greens; 2122 - Potted plants;

Field Of Science
1081 - Breeding;
Goals / Objectives
Ornamental plants are one of the largest agricultural commodity groups in Florida and many other states in the U.S. Caladium, gerbera, impatiens, lantana, ligustrum, and nandina are very important crops for the ornamental plant industry in Florida and other states. The main goal of this project is to develop new cultivars with enhanced disease resistance, plant yield potential, plant and flower quality, landscape performance, or reduced or eliminated invasive potential. The availability of these cultivars can keep the ornamental plant industry fresh, competitive, and profitable. The specific objectives of this project are: (1) Improve disease resistance in caladium and gerbera and produce new cultivars with enhanced disease resistance, increased crop yield, and improved plant performance and quality; (2) Sterilize lantana, ligustrum, and nandina to produce environmentally friendly alternatives to existing invasive types for for continued propagation, production and use; and (3) Develop and apply molecular markers, genetic linkage maps, and transgenic techniques to increase disease resistance in gerbera and impatiens.
Project Methods
Objective 1: Advanced caladium breeding lines and cultivars with resistance to Pythium root rot, Fusarium tuber rot, and/or bacterial blight will be cross-pollinated to create new breeding populations. Progeny will be screened and evaluated for plant vigor, growth habit, foliage color, sunburn tolerance, yield potential, landscape performance, and suitability for pot plant production. Promising breeding lines will be evaluated for resistance to Pythium root rot, Fusarium tuber rot, and/or bacterial blight. Superior breeding lines will be released as new cultivars. Efforts in gerbera breeding will be focused on transferring powdery mildew resistance into two series of cultivars, one for production and use in large containers and one for production and use in smaller containers. Resistant breeding lines will be crossed with breeding lines with desirable horticultural attributes and progeny will be subjected to powdery mildew screening. Selected resistant lines will be backcrossed for two to four generations to produce desirable breeding lines, which will be screened for powdery mildew resistance. Powdery mildew-resistant lines will be further evaluated for plant vigor and form, flower form, color, counts, etc. Superior lines will be released as asexually propagated new cultivars.Objective 2: Tetraploids will be induced or identified and then crossed with diploids to produce triploids. Seed germination will be optimized using varying substrates, temperatures, and hormone treatments. Triploids will identified through flow cytometry-based ploidy analysis and verified by chromosome counting. The sterility of triploids will be assessed by pollen staining, hand pollination, fruit/seed production, and seed germination. Highly sterile breeding lines with desirable plant growth habit, bright flower color, superior flower quality, excellent flowering power, and plant performance will be selected. The selections will be evaluated in internal replicated trials in Wimauma (central Florida) and Citra (north Florida) as well as grower trials, and compared to industry standards. The best sterile breeding lines will be released as new cultivars.Objective 3: New mapping populations will be developed and phenotyped in replicated, multi-season experiments to obtain reliable data for powdery mildew (PM) resistance. The progeny of the mapping populations will be genotyped at tens of thousands of single nucleotide polymorphism (SNP) sites using the recently developed genotyping-by-sequencing approach. The order and genetic distance between these SNP sites will be calculated to create a genetic linkage map of the targeted chromosome regions and finely map the quantitative trait loci for PM resistance. The developed molecular markers will be converted into KASP markers that can be readily used by plant breeders. The Arabidopsis NPR1 gene will be introduced into downy mildew-susceptible impatiens cultivars using the Agrobacterium-mediated transformation method, and transgenic impatiens plants will be evaluated for copy number and expression level of introduced NPR1 gene and resistance to downy mildew.?

Progress 10/01/20 to 03/14/21

Outputs
Target Audience:Commercial floricultural businesses (growers, nurseries, and landscapers), county extension agents, master gardener volunteers, and researchers, and interested general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This year this project provided technical and professional training for two graduate students, one undergraduate student, one postdoc, two biological scientists, and one international visiting graduate student. How have the results been disseminated to communities of interest?Results from this project were presented at the American Society for Horticultural Science 2020 Annual Meeting, the National Association for Plant Breeders 2020 Annual Meeting, and a number of extension events. Part of these results were published in scientific journals including Horticulture Research, HortScience, and Scientia Horticulturae. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? 1. Replicated field trials of advanced caladium breeding lines: Twenty-eight advanced caladium breeding lines were tested in a replicated field trial with 11 commercial caladium cultivars. The breeding lines were evaluated for plant growth, plant performance, sunburn tolerance, resistance to leaf blight, and tuber yield. A number of very promising lines have been identified as potential releases after further testing. Nearly 360 pounds of dried, cured tubers of 20 advanced breeding lines were delivered to major caladium grower trials in central Florida for their on-farm field trials. 2. Non-replicated trials and increase of caladium breeding lines: A total of 112 advanced breeding lines were tested in non-replicated, observational trials. All breeding lines were evaluated for plant growth, performance, sun tolerance, resistance to leaf blight, and tuber yield. A total of 21 promising breeding lines were selected for further trials in the next year. 3. Releasing two new caladium cultivars: 'UF-15-441' ('Firefly') originated from a cross between 'Aaron' and 'White Wing'. Plants of 'UF-15-441' are characterized by wide white lance leaves and have shown good plant performance, good resistance to leaf spot diseases, strong tolerance to sunburns, and good tuber yield potential. Tubers have multiple branches, and de-eyeing may be unnecessary when tubers are used to produce plants in small containers. This caladium can perform well in both shady and sunny locations in the landscape. 'UF-16-597' ('Spicy Lizard') was from a cross between 'Tricolor Butterfly' and the proprietary caladium breeding line UF-317. 'UF-16-597' is a novel lance-leaved cultivar characterized by wide lance hear-shaped leaves, thick green main veins, and multiple burgundy spots on the leaves. This caladium has shown excellent tolerance to sunburns, strong resistance to leaf spot diseases, and excellent tuber yield potential. It is suited for use in the landscape and containers. Anecdotally, this caladium may have better cold tolerance than other caladium cultivars. 4. Induction and characterization of tetraploids in gerbera daisy. Tetraploids were induced in gerbera daisy by treating the apical meristems of seedlings with colchicine. The nuclear DNA content of tetraploid gerbera was increased to 10.41 pg/2C from 5.22 pg/2C. Induced tetraploids had larger, fewer stomata and wider, thicker leaves than diploids, resulting an increased leaf index. With tetraploidization, flower scapes became thicker, flowers were larger, ray florets became wider, and the center eye (composed of disc florets) was larger. Induced tetraploids showed lower but still high pollen stainability and are expected to be quite fertile and be able to serve as parents for production of triploids. Some of the morphological changes associated with induced tetraploidy, including larger flowers, thicker ray florets, larger eyes and/or thicker scapes, will be beneficial for gerbera flower quality and vase life, while other changes such as stomatal size and density and thicker leaves may change and improve gerbera tolerance to stresses. 5. Characterization of downy mildew resistance in impatiens. Recent outbreaks of impatiens downy mildew (IDM) in many countries have caused huge economic losses. A system to reveal plant-pathogen interactions in the early stage of infection and quickly assess resistance/susceptibility of plants to DM is desired. Thirty-two cultivars of Impatiens walleriana and I. hawkeri were evaluated for their responses to IDM at cotyledon, first/second pair of true leaf, and mature plant stages. All I. walleriana cultivars were highly susceptible to IDM. While all I. hawkeri cultivars were resistant to IDM starting at the first true leaf stage, many (14/16) were susceptible to IDM at the cotyledon stage. Two cultivars showed resistance even at the cotyledon stage. Histological characterization showed that the resistance mechanism of the I. hawkeri cultivars resembles that in grapevine and type II resistance in sunflower. Integrating full-length transcriptome sequencing (Iso-Seq) and RNA-Seq resulted in the first reference transcriptome for Impatiens, which comprised of 48,758 sequences with an N50 length of 2,060 bp. Comparative transcriptome and qRT-PCR analyses revealed strong candidate genes for IDM resistance, including three resistance genes orthologous to the sunflower gene RGC203, a potential candidate associated with DM resistance. 6. Characterizing the genome size and karyotype of Lantana species. The genome size, somatic chromosome number, karyotype of five lantana species, L. camara (L. strigocamara), L. canescens, L. depressa, L. involucrata, and L. montevidensis, were determined. The nuclear genome size of these species ranges from 2.74 pg/2C to 6.29 pg/2C. Four chromosome numbers (2n = 2x = 22, 24, 2n = 3x = 36, and 2n = 4x = 44) were observed in these species. The karyotype of L. camara 'Lola' and 'Denholm White' is 20m + 2sm; the karyotype for L. canescens is 12m + 12 sm; the karyotype for L. depressa var. depressa is 44m; the karyotype for L. involucrata is 10m + 14sm, and the karyotype for L. montevidensis is 32m + 4sm. Satellites were identified in all five species but associated with a different chromosome group in different species.

Publications

  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Bhattarai, K., A. Kareem, and Z. Deng. 2021. In vivo induction and characterization of polyploids in gerbera daisy. Scientia Horticulturae 282 (2021) 110054. https://doi.org/10.1016/j.scienta.2021.110054.
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Deng, Z., N.A. Peres, and J. Desaeger. 2021. Two lance-leaved caladium cultivars, Pink Panther and Crimson Skye. HortScience 56(7):853-859. https://doi.org/10.21273/HORTSCI15854-21.
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Parrish, S., R. Qian, and Z. Deng. 2021. Genome size and karyotype studies in five species of lantana (Verbenaceae). HortScience 56(3):352-356. https://doi.org/10.21273/HORTSCI15603-20
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Qian, R., S. Parrish, S.B. Wilson, G.W. Knox, and Z. Deng. 2021. Morphological and cytological characterization of fiver porterweed (Stachytarpheta) selection. HortScience 56(3):330-335. https://doi.org/10.21273/HORTSCI15594-20
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Peng, Z., Y. He, S. Parajuli, Q. You, W. Wang, K. Bhattarai, A.J. Palmateer, and Z. Deng. 2021. Integration of early disease resistance phenotyping, histological characterization and transcriptome sequencing reveals insights into downy mildew resistance in impatiens. Horticulture Research 108:1-22. https://doi.org/10.1038/s41438-021-00543-w
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Deng, Z., Z. Peng, Y. He, S. Parajuli, Q. You, W. Wang, K. Bhattarai., and A. Palmateer. 2021. Phenotypic, histological and transcriptomic characterization of downy mildew resistance in Impatiens hawkeri. HortScience 56(9):S33.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Parrish, S. and Z. Deng. 2021. Discovery and characterization of triploid caladium breeding lines. HortScience 56(9):S34.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Parrish, S., M.E. Kane, and Z. Deng. 2021. Morphological, cytological, and molecular characterization of new caladium somaclonal variants. HortScience 56(9):S263.
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Wilson, S.B., J. Rycyna, Z. Deng, and G.W. Knox. 2021. Summary of 26 Heavenly bamboo selections evaluated for invasive potential in Florida. HortTechnology. https://doi.org/10.21273/HORTTECH04798-21.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Deng, Z. 2021. Use of in vitro techniques to increase chromosome number and morphological variation in caladium. 2021 National Association of Plant Breeders annual conference, Ithaca, NY, 15-18 August 2021.


Progress 03/15/16 to 03/14/21

Outputs
Target Audience:Commercial floricultural businesses (growers, nurseries, and landscapers), county extension agents, master gardener volunteers, and researchers, and interested general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided technical and professional training for six graduate students (four MS and two PhD students), five undergraduate students, and six postdoctoral research associates.? How have the results been disseminated to communities of interest?Results from this project were presented as two international conferences (International Horticultural Congress and the Plant & Animal Genome Conferences), 22 national conferences (the American Society for Horticultural Science Annual Meetings, and the National Plant Breeder Association), 12 state professional meetings (Florida State Horticultural Society annual meetings, Florida Exotic Plants annual meetings), and 26 extension and growers meetings. Results were published in two book chapters; 31 refereed papers in 13 scientific journals including HortScience, Journal of the American Society for Horticultural Science, Plant Cell, Tissue and Organ Culture, Scientia Horticulturae, Horticulture Research, BMC Plant Biology, Frontiers in Plant Science, G3: Genes, Genomes, and Genetics; two non-refereed papers, 23 extension publications, and 36 published abstracts. ? What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Objective 1 - Improve disease resistance in caladium and gerbera and produce new cultivars with enhanced disease resistance, plant yield potential, plant and flower quality, and landscape performance. Nine superior advanced caladium breeding lines were released as new cultivars ['UF-R1022' ('Icicle'), R1409 ('Sea Foam Pink'), 'UF15-55' ('Pink Panther'), 'UF15-19' ('Lava Glow'), 'UF15-21' ('White Lightning'), 'UF15-54 ('Crimson Skye'), 'UF R1410 ('Dots Delight'), 'UF-15-441' ('Firefly'), and 'UF-16-597' ('Spicy Lizard'). These cultivars have novel leaf characteristics, improved tuber yield potential, excellent sunburn tolerance, and/or superior landscape and container performance. In addition, one of these cultivars showed improved resistance to Fusarium tuber rot and bacterial leaf blight, two cultivars exhibited better resistance to Fusarium tuber rot and Pythium root rot, one cultivar had better resistance to Pythium root rot and bacterial leaf blight, one cultivar showed strong resistance to bacterial leaf blight, and one cultivar had resistance to root-knot nematodes. Florida growers have licensed all nice cultivars for commercial production and sales. The availability of these cultivars has enriched the plant palette for greenhouse growers, nurseries, and the general public. Objective 2 - Sterilize lantana, ligustrum, and nandina to produce environmentally friendly alternatives to existing invasive types for commercial propagation, production, and landscape use in Florida. Three new triploid lantana cultivars ['UF-1011-2' ('Bloomify Rose'), ('UF-1013A-2A' ('Bloomify Red'), and 'UF-1013-1' ('Luscious® Royale Red Zone™ have been released, and three plant patents have been awarded. These cultivars have excellent growth and branching habits, produce attractive plants and flowers, and perform well in containers and in the gardens in many states. Importantly, their pollen stainability has been reduced to below 10%, seed production reduced to below 0.05 fruit per peduncle, and female fertility index reduced to nearly 0. In hand pollinations, these cultivars did not set fruit or did not effect fruit set on Lantana depressa. Thus, these cultivars are male and female sterile, and non-invasive. These cultivars have been licensed by major international horticultural companies for propagation, and many growers are producing these cultivars. We evaluated seven U.S. trailing lantana cultivars and one invasive Australian trailing lantana form for their DNA content, ploidy level, pollen stainability, fruit production, plant growth and leaf morphology. Results showed that there are two forms of trailing lantana, and that U.S. trailing lantana cultivars are non-invasive. In addition, tetraploid nandina and ligustrum lines have been induced and characterized. These tetraploids will be used to produce triploid nandina and Ligustrum in future projects. Objective 3 - Improve cultivar development through understanding the mode of inheritance of important disease resistance traits. Research was focused on powdery mildew resistance in gerbera and downy mildew resistance in impatiens. Results showed that the inheritance for powdery mildew resistance in gerbera is a quantitative trait. A major quantitative trait locus (QTL) explaining about 17% of the phenotypic variation in powdery mildew resistance was located onto gerbera linkage group 16 and tagged with two flanking SNP markers. Thirty-two cultivars of Impatiens walleriana and I. hawkeri were evaluated for their response to impatiens downy mildew at cotyledon, first/second pair of true leaf, and mature plant stages. All I. hawkeri cultivars were resistant to impatiens downy mildew beginning at the first true leaf stage, but many cultivars were susceptible to downy mildew at the cotyledon stage. Two cultivars were found to be resistant to downy mildew even at the cotyledon stage. The resistance mechanism of the I. hawkery cultivars shares high similarity with that in grapevine and sunflower. Additional studies were centered around somaclonal variation and cytogenetics in caladium and lantana. Several dozens of caladium somaclonal variants were identified and characterized, and it was found that chromosome loss is the main genetic cause of somaclonal variation in caladium. The genome size, somatic chromosome number, karyotype of five lantana species, L. camara (L. strigocamara), L. canescens, L. depressa, L. involucrata, and L. montevidensis, were determined. Four chromosome numbers were observed in these species. Objective 4 - Development and application of molecular markers, genetic linkage maps, and transgenic techniques for increasing disease resistance in gerbera and impatiens. A genome-wide linkage map was developed for gerbera using the genotyping by sequencing approach. The map consists of 791 SNP markers coving nearly 2000 cM across 27 linkage groups. SNP markers were developed for powdery mildew resistance in gerbera. To develop genomic resources for future development of molecular markers in gerbera, impatiens, and lantana, the leaf transcriptomes of gerbera and impatiens and the ovary transcriptome of lantana were sequenced, assembled, and analyzed. The leaf transcriptomes of gerbera were assembled from two breeding lines with contrasting traits for flower color, peduncle length, flower form, and powdery mildew resistance. Functional annotation of these leaf transcriptomes revealed several hundred NB-LRR genes that are known to confer disease resistance in plants and more than a dozen of susceptibility genes. Large numbers of SNPs and SSR sites were discovered for future development of molecular markers. The leaf transcriptomes of three impatiens cultivars with different responses to P. destructor were sequenced using the Illumina short read and the PacBio long read sequencing platforms. De novo assembly of these leaf transcriptomes resulted in the first reference leaf transcriptome for impatiens. Analysis of these transcriptomes led to the identification of three candidate resistance genes for resistance to downy mildew in New Guinea impatiens cultivars. The transcriptomes of young ovaries of two lantana genotypes that produces or do not produce unreduced female gametes were sequenced and assembled. The de novo transcriptome assembly resulted in nearly 30,000 unique transcript sequences containing full-length coding sequences. More than 200 transcripts were associated with the biological processes of gamete production or control of unreduced gamete production. Bioinformatic analysis also led to the discovery of several hundred NB-LRRs in the genomes of Petunia axillaris and P. inflata. Petunia inflata contains more NB-LRR genes than P. axillaris, and P. inflata may play more important roles in P. hybrida resistance to diseases. Two approaches were used to increase impatiens resistance to downy mildew caused by Plasmopara destructor. Tetraploid impatiens had lower downy mildew disease severity and lower sporangia densities after artificial inoculation of spores of P. destructor. Impatiens transgenic lines expressing the Arabidopsis NPR1 also were less susceptible to downy mildew in leaf disc and in-vivo inoculation assays.

Publications


    Progress 10/01/19 to 09/30/20

    Outputs
    Target Audience:Commercial floricultural businesses (growers, nurseries, and landscapers), county extension agents, master gardener volunteers, and researchers, and interested general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This year this project provided technical and professional training for two graduate students, one postdoc, and one biological scientist. How have the results been disseminated to communities of interest?Results from this project were presented at the Florida State Horticultural Society 2020 Annual Meeting (three presentations), the American Society for Horticultural Science 2020 Annual Meeting (six presentations), and a number of extension events (three presentations). Part of these results were published in scientific journals including HortScience, Scientia Horticulturae, BMC Plant Biology, and Plant Cell, Tissue and Organ Culture. Published one article in a newsletter, and contributed to four articles published in newspapers, magazines, blogs, etc. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? 1. Replicated field trials of advanced caladium breeding lines: Twenty-nine advanced caladium breeding lines were tested in a replicated field trial with 11 commercial caladium cultivars. The breeding lines were evaluated for plant growth, plant performance, sunburn tolerance, resistance to leaf blight, and tuber yield. A number of very promising lines have been identified as potential releases. More than 250 pounds of dried, cured tubers of 10 new advanced breeding lines were delivered to major caladium grower trials in central Florida for their on-farm field trials. 2. Non-replicated trials and increase of caladium breeding lines: A total of 150 advanced breeding lines were tested in non-replicated, observational trials. All breeding lines were evaluated for plant growth, performance, sun tolerance, resistance to leaf blight, and tuber yield. A total of 120 breeding lines were selected for further trials in the next year. 3. Evaluating caladium cultivars and breeding lines for resistance to Xanthomonas leaf blight and other diseases. Twenty-two caladium cultivars and 44 new caladium selections were planted in the ground beds and inoculated with Xanthomonas cell suspension. One cultivar and six new selections showed strong resistance to this bacterium. In addition, dozens of caladium cultivars and new selections were evaluated for resistance to Fusarium tuber rot, Pythium root rot, and root-knot nematodes, in collaboration with plant pathologists and nematologists. 4. Releasing five caladium cultivars: Five new caladium cultivars were released in 2020. 'Lava Glow' is a fancy leaf caladium variety that produces many bright red to red-purple, heart-shaped leaves. It has shown excellent tolerance to sunburns and resistance to leaf spot diseases. 'Dots Delight' is a lance leaf variety with white veins and light pink spots. 'Crimson Skye' has a compact stature and produces many heart-shaped leaves with pink blotches. 'Pink Panther' has a novel combination of leaf characters, wide lance leaves, upright and sturdy petioles, deep pink main veins, light pink blotches, and ruffled leaf margins. 'White Lightning' produces large lance-leaves with a large white center and green margins. These new varieties are well suited for growing in containers and in the landscapes from full sun to shady locations. 5. Morphological, cytological and molecular marker analyses of caladium variants: Twenty caladium variants were identified among 'Tapestry' plants that were regenerated from leaf cultures treated with or without colchicine. These variants showed changes in leaf main vein color and coloration pattern and were separated into 10 groups based on leaf morphological changes. Five variants contained 3.3% to 9.7% more nuclear DNA than the wildtype and gained one, two or three chromosomes, while four variants contained 3.0% to 4.8% less nuclear DNA and lost one chromosome. Five, out of 22, simple sequence repeat-based molecular markers detected DNA banding pattern changes in 13 of the 20 variants. Two molecular markers (CaM24 and CaM62) detected DNA banding pattern changes in the same four variants, suggesting that these two markers may be located in the same chromosomal segment. Strong association between leaf characteristics (leaf blotching and main vein color) and molecular banding pattern changes with molecular marker CaM42 were observed in six variants, indicating that CaM42 may be associated with gene loci controlling leaf blotching and leaf main vein color in caladium. 6. Sequencing and analysis of gerbera leaf transcriptomes: The leaf transcriptomes of two gerbera genotypes, UFGE 4033 and 06-245-3, that were resistant and susceptible to PM, respectively, were sequenced, assembled and analyzed. De novo assembly of these leaf transcriptomes using four complementary pipelines resulted in 145,348 transcripts, of which 67,312 transcripts contained open reading frames and 48,268 were expressed in both genotypes. A total of 494 transcripts were found to be likely involved in disease resistance, and 17 and 24 transcripts were up- and down-regulated, respectively, in UFGE 4033 compared to 06-245-3. These gerbera disease resistance transcripts were most similar to the NBS-LRR class of plant resistance genes conferring resistance to various pathogens in plants. Four disease susceptibility transcripts (MLO-like) were expressed only or highly expressed in 06-245-3, offering excellent candidate targets for gene editing for powdery mildew resistance in gerbera. A total of 449,897 SNPs and 19,393 SSRs were revealed in the gerbera transcriptomes, which can be a valuable resource for developing new molecular markers. 7. Genotyping by sequencing and genetic linkage map construction in gerbera. A gerbera population consisting of 88 individuals was developed by crossing a PM-resistant gerbera breeding line, UFGE 4033, and a powdery mildew (PM)-susceptible breeding line 06-245-3. Individuals of this segregating population was genotyped by sequencing (GBS) and phenotyped for resistance to powdery mildew. GBS performed with two restriction enzymes BamHI and NsiI generated more than two million short reads per individual. FreeBayes analysis and VCFtools filtering identified 791 high-quality single nucleotide polymorphisms (SNPs). Based on these SNPs, a genetic linkage map was developed, consisting of 27 linkage groups and spanning 1,192.3 cM. QTL analysis revealed one locus in LG16 that explained 16.6% to 20.4% of the PM resistance variance and another locus in LG18 accounting for 13.5% of the PM resistance variance. 8. Characterization of porterweed taxa: The morphological features, pollen stainability and morphology, nuclear DNA content, and chromosome number of five porterweed selections were assessed. Coral porterweed (S. mutabilis), 'Naples Lilac' porterweed (S. cayennensis × S. mutabilis 'Violacea'), and nettleleaf porterweed (S. cayennensis) had the largest plant heights. Flower number was significantly higher in nettleleaf porterweed, jamaican porterweed (S. jamaicensis), and U*J3-2 porterweed (S. cayennensis × S. jamaicensis) with an average of 65 - 72 flowers per inflorescence. Internode length and flower width of jamaican porterweed had much lower values than the other selections. Coral porterweed recorded the lowest pollen stainability with only 10.6% stainability but had the largest relative pollen production. 'Naples Lilac' porterweed had the highest DNA content with an average of 3.79 pg/2C similar to jamaican porterweed with 3.73 pg/2C. Ploidy levels varied between selections, and the basic chromosome number was x = 28. Coral, jamaican, and 'Naples Lilac' porterweed had 2n = 6x = 168 chromosomes, first reported in this genus. These results can provide a guide and a new tool to distinguish native and non-native porterweed and may aid future breeding toward the production of non-invasive cultivars. 9. Induction and characterization of tetraploids in Ligustrum sinense: Pure L. sinense tetraploid plants were inducted by applying colchicine to the shoot tips of emerging seedlings before true leaves emerged. Treatments with 0.1% or 0.2% colchicine resulted in higher frequencies of pure tetraploids (30.8 %) and lower seedling mortality compared to higher concentrations (0.3% and 0.4%). Flow cytometry analysis showed that L. sinense tetraploids contained 4.67 pg/2C nuclear DNA content, 94.6% higher than that of its diploids. Compared to diploids, L. sinense tetraploids showed significant changes in morphology. Tetraploid plants were more compact and 25.4% shorter and had 20.1% fewer branches; their leaves were 48.0% larger and had 71.8% higher fresh and dry weight. Stomata on tetraploid leaves were 45.7% lower in density and 32.2% larger in size than those on diploid leaves.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2020 Citation: Bhattarai, K., A. Conesa, S. Xiao, N.A. Peres, D.G. Clark, S. Parajuli, and Z. Deng. 2020. Sequencing and analysis of gerbera daisy leaf transcriptomes reveal disease resistance and susceptibility genes differentially expressed and associated with powdery mildew resistance. BMC Plant Biology 20:539. https://doi.org/10.1186/s12870-020-02742-4
    • Type: Journal Articles Status: Published Year Published: 2020 Citation: Cao, Z. and Z. Deng. 2020. Morphological, cytological and molecular marker analyses of Tapestry caladium variants reveal diverse genetic changes and enable association of leaf coloration pattern loci with molecular markers. Plant Cell, Tissue and Organ Culture 143:363-375. https://doi.org/10.1007/s11240-020-01922-2
    • Type: Journal Articles Status: Published Year Published: 2020 Citation: Czarnecki, D.M. and Z. Deng. 2020. Assessment of the female fertility of 26 commercial Lantana camara cultivars and six experimental lines. HortScience 55 (5):709-715. https://doi.org/10.21273/HORTSCI14963-20
    • Type: Journal Articles Status: Published Year Published: 2020 Citation: Fetouh, M.I., Z. Deng, S.B. Wilson, C. Reinhardt-Adams, and G.W. Knox. 2020. Induction and characterization of tetraploids in Chinese privet (Ligustrum sinense Lour.). Scientia Horticulturae. 271:109482. https://doi.org/10.1016/j.scienta.2020.109482
    • Type: Journal Articles Status: Published Year Published: 2020 Citation: Wilson, S.B., C. Steppe, Z. Deng, G.W. Knox, E. van Santen, and K. Druffel. 2020. Landscape performance, flowering and female fertility of eight trailing lantana varieties grown in central and northern Florida. HortScience 55(11):1737-1743. https://doi.org/10.21273/HORTSCI15120-20
    • Type: Other Status: Published Year Published: 2020 Citation: Deng, Z. 2020. Five new caladium cultivars released and available for your patios, gardens and yards. UF/IFAS Gulf Coast Research and Education Center ENews (Nov. 18, 2020).
    • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Bhattarai, K. and Z. Deng. 2020. Linkage map construction and QTL analysis of gerbera daisy for powdery mildew resistance (oral). HortScience 55(9) Supplement: S69.
    • Type: Journal Articles Status: Published Year Published: 2020 Citation: Deng, Z., S.B. Wilson, X. Ying, C. Chen, R. Freyre, V. Zayas, and D.M. Czarnecki. 2020. UF-1013-1: An infertile cultivar of Lantana camara. HortScience 55(6):953-958. https://doi.org/10.21273/HORTSCI14911-20
    • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Bhattarai, K. and Z. Deng. 2020. Genome-wide identification of NBS-encoding disease resistance genes in gerbera (Gerbera hybrida) (poster). HortScience 55(9) Supplement: S121-S122.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Deng, Z. 2020. Progress in gerbera breeding. HortScience 55(9) Supplement: S68-69.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Parrish, S.B., J.E. Polston, Z. Deng, and M.E. Kane. 2020. Production of pathogen-eradicated caladium seed stock using meristem-tip culture. HortScience 55(9) Supplement: S167-S168.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Parrish, S.B., R. Qian, and Z. Deng. 2020. Cytological and karyotyping analysis of five Lantana species (poster). HortScience 55(9) Supplement: S213-S214.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Rycyna, J., S.B. Wilson, Z. Deng, and G.A. Knox. 2020. Evaluation of 25 Nandina domestica (heavenly bamboo) cultivars for invasive potential in Florida (poster). HortScience 55(9) Supplement: S310-S311.


    Progress 10/01/18 to 09/30/19

    Outputs
    Target Audience:Commercial floricultural businesses (growers, nurseries, and landscapers), county extension agents, master gardener volunteers, and researchers, and interested general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This year this project provided technical and professional training for one graduate student, two undergraduate students, two postdocs, and two biological scientists. How have the results been disseminated to communities of interest?Results from this project were presented at the Florida State Horticultural Society 2019 Annual Meeting, the Florida Exotic Pest Plant 2019 Annual Meeting, the American Society for Horticultural Science 2019 Annual Meeting, and a number of extension events. Part of these results were published in scientific journals including HortScience, Journal of Environmental Horticulture, Horticulture Research, and Plants. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? 1. Replicated field trials of advanced caladium breeding lines: Nineteen advanced caladium breeding lines were tested in a replicated field trial with six commercial caladium cultivars. The breeding lines were evaluated for plant growth, plant performance, sunburn tolerance, resistance to leaf blight, and tuber yield. A number of very promising lines have been identified as potential releases after further testing. Nearly 200 pounds of dried, cured tubers of thirteen advanced breeding lines were delivered to major caladium grower trials in central Florida for their on-farm field trials. 2. Non-replicated trials and increase of caladium breeding lines: A total of 269 advanced breeding lines were tested in non-replicated, observational trials. All breeding lines were evaluated for plant growth, performance, sun tolerance, resistance to leaf blight, and tuber yield. A total of 175 breeding lines were selected for further trials in the next year. 3. Identifying and analyzing candidate disease resistance and susceptibility genes in gerbera transcriptomes: We sequenced the leaf transcriptomes of two gerbera lines with contrasting traits for flower color, peduncle length, flower form and powdery mildew resistance. Transcriptome assembly using Trinity, TransAbyss, Velvet and Soapdenovo resulted in 145,348 contigs with an N50 of 1124 nucleotides and a mean contig length of 761 nucleotides. A total of 67,312 contigs contain open reading frames. Functional annotation of these contigs using Blast2Go identified 494 genes involved in disease resistance, including 382 genes containing the nucleotide-binding site (NBS) domain that is present in many cloned plant disease resistance genes. Among these NBS genes, 69 belong to the recognition of Peronospora parasitica (RPP) gene family. There were 306 genes containing the coiled-coil (CC) domain and 31 genes containing the Toll-like receptors (TIR) domain. Fifteen susceptibility genes were identified, belonging to the mildew resistance locus o (MLO) or the Long Vegetative Phase 1 (LOV1) gene family. 4. Partial sequencing of the gerbera genome using the PacBio SMRT sequencing technology: The genomic DNA of a powdery mildew-resistant gerbera line was sequenced using the PacBio RSII platform and the P6-C4 chemistry to a depth of about 3x. Sequence reads had an average N50 of 16.7 kb, a mean read length of 11,894 kb, and a mean read score of 0.84. NB-LRR genes in the gerbera genome were identified using the available homologous sequences from the sunflower and lettuce genomes. 5. Disease resistance genes in Petunia genomes: The nucleotide-binding site leucine-rich repeat (NBS-LRR) genes play an important role in recognizing pathogens and conferring disease resistance in plants. We conducted a comprehensive characterization of this group of disease resistance genes in Petunia in a genome-wide manner. Using multiple bioinformatic tools, we discovered a total of 267 and 388 NBS genes in the genomes of P. axillaris and P. inflata, respectively. These NBS genes were characterized for the presence of the Toll/Interleukin-1 receptor (TIR), coiled coil (CC) and/or LRR domains. For all classes of NBS genes, there are more genes in P. inflata than in P. axillaris. Surprisingly, most of the Petunia NBS genes are of the non-TIR type, and only very few of the TIR type. More than half (55.9%) of the NBS genes contain the LRR domain while the remaining lack a typical LRR region. P. inflata has 146 CC-NBS-LRR genes, more than double of the number (68) in P. axillaris. It is suspected that the NBS-LRR genes from P. inflata may play more important roles in P. hybrida resistance to diseases. 6. Lantana ovary transcriptome: The formation of unreduced female gametes (UFGs) is a major factor contributing to its invasiveness and has severely hindered the development of sterile cultivars. To enrich the genomic resources and gain insight into the genetic mechanisms of UFG formation in lantana, we sequenced, annotated and analyzed the transcriptomes of young ovaries of two lantana genotypes, GDGHOP-36 that produces UFGs and the cultivar Landmark White Lantana that does not produce UFGs. The de novo transcriptome assembly resulted in a total of 90,641 unique transcript sequences with an N50 of 1692 bp, among which, 29,383 sequences contained full-length coding sequences (CDS). There were 214 transcripts associated with the biological processes of gamete production and 10 gene families orthologous to genes known to control unreduced gamete production in Arabidopsis. We identified 925 transcription factor (TF)-encoding sequences, 91 nucleotide-binding site (NBS)-containing genes, and gene families related to drought/salt tolerance and allelopathy. 7. Evaluating the potential of trailing lantana (Lantana montevidensis) in Florida: Seven U.S. trailing lantana cultivars and one invasive Australian training lantana form were evaluated for their DNA content, ploidy level, pollen stainability, fruit production, plant growth and leaf morphology. The Australian trailing lantana differed morphologically from U.S. varieties in its smaller habit, leaves (which had serrate-crenate leaf margins, and less appressed hairs), heavy fruiting, and cold sensitivity (observational reduced growth and flowering during winter months). Nuclear DNA content analysis suggests that Australian trailing lantana is likely a tetraploid and all other varieties evaluated were likely triploids with high levels of sterility. Pollen stainability of Australian trailing lantana was moderately high (58.83%), whereas pollen production was rarely observed in all other varieties. We showed that there are two forms of trailing lantana, the U.S. varieties distinguished by their leaf and flower morphology, ploidy level, and the absence of fruit and viable pollen.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Cao, Z., Y. Guo, Q. Yang, Y. He, M. Fetouh, R.M Warner, and Z. Deng. 2019. Genome-wide identification of quantitative trait loci for important plant and flower traits in petunia using a high-density linkage map and an interspecific recombinant inbred population derived from Petunia integrifolia and P. axillaris. Horticulture Research 6:27. DOI 10.1038/s41438-018-0091-5.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Deng, Z. and N.A. Peres. 2019. Sea Foam Pink caladium. HortScience 54(9):1637-1640.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Peng, Z., K. Bhattarai, S. Parajuli, and Z. Deng. 2019. Transcriptome analysis of young ovaries reveals candidate genes involved in gamete formation in Lantana camara. Plants 8(8):263. https://doi.org/10.3390/plants8080263
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Deng, Z. Caladium breeding and genetic research at the University of Florida. HortScience 54(9) Supplement S158.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Peng, Z. and Z. Deng. 2019. Genome-wide analysis of NBS-LRR genes in Petunia. HortScience 54(9) Supplement S219.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Steppe, C., S.B. Wilson, Z. Deng, K. Druffel, and G.W. Knox. 2019. Landscape performance and fruiting of non-invasive Lantana spp. grown in north and center Florida. Florida Exotic Pest Plant Council (FLEPPC) 2019 Annual Symposium Program & Abstracts. Page 29. https://bugwoodcloud.org/CDN/fleppc/Symposia/2019/program&abstracts.pdf
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Steppe, C.N., S.B. Wilson, Z. Deng, K. Druffel, and G.W. Knox. 2019. Morphological and cytological comparison of eight varieties of trailing lantana (Lantana montevidensis) grown in Florida. HortScience 54(12):2134-2138.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bhattarai, K. and Z. Deng. 2019. Identification and characterization of disease resistance and susceptibility genes in gerbera leaf transcriptomes. HortScience 54(9) Supplement S118.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bhattarai, K. and Z. Deng. 2019. SMRT genome sequencing in gerbera and NB-LRR genes in the gerbera genome. HortScience 54(9) Supplement S304-S305.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Bechtloff, A., C. Reinhardt-Adams, S. Wilson, Z. Deng, and C. Wiese. 2019. Insights from Southeastern US nursery growers guide research for sterile ornamental cultivars. J. Environ. Hort. 37(1):9-18.


    Progress 10/01/17 to 09/30/18

    Outputs
    Target Audience:Commercial floricultural businesses (growers, nurseries, and landscapers), county extension agents, and researchers, and interested general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided technical and professional training for three graduate students, one undergraduate student, and one high school student. How have the results been disseminated to communities of interest?Results from this project were presented at the Florida State Horticultural Society 2018 Annual Meeting, the American Society for Horticultural Science 2018 Annual Meeting, and 15 other outreach and extension events. Part of these results were published in scientific journals including G3: Genes, Genomes, Genetics, HortScience, Horticulture Research, and the International Journal of Molecular Science. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? 1. Replicated field trials of advanced caladium breeding lines: Twenty advanced caladium breeding lines were tested in a replicated field trial with seven commercial caladium cultivars. The breeding lines were evaluated for plant growth, plant performance, sunburn tolerance, resistance to leaf blight, and tuber yield. A number of very promising lines have been identified as potential releases after further testing. Seven of these advanced breeding lines were chosen for grower trials in central Florida. 2. Non-replicated trials and increase of caladium breeding lines: A total of other 308 advanced breeding lines were tested in non-replicated, observational trials. All breeding lines were evaluated for plant growth, performance, sun tolerance, resistance to leaf blight, and tuber yield. A total of 216 breeding lines were selected for further trials in the next few years. 3. Field evaluation of caladium somaclonal variants: More than 40 caladium somaclonal variants were grown in the field and evaluated for plant growth, leaf color, and sunburn tolerance. A number of them showed value as future releases. Others have shown interesting changes in plant height, leaf shape, leaf color, or coloration pattern, and these will be useful for genetic studies. Approximately 50 somaclonal variants identified from the tissue culture liners of four commercial cultivars, 'Aaron', 'Carolyn Whorton', 'Freida Hemple', and 'White Christmas', were increased and evaluated in a shadehouse. Remarkable differences have been observed among these somaclonal variants. 4. Phenotyping of gerbera segregating populations for resistance to powdery mildew: Powdery mildew (PM) is one of the most challenging diseases to gerbera daisy production. A large population of gerbera progeny resulting from crossing of a PM-resistant and susceptible line were evaluated for PM resistance. The powdery mildew severity was rated and AUDPC per week was plotted against the frequency of individuals. A uni-model histogram was observed, indicating the inheritance for powdery mildew resistance is a quantitative trait controlled by quantitative trait loci (QTL). 5. Assembling and analysis of gerbera leaf transcriptomes: A gerbera leaf transcriptome assembly, consisting of 124,348 contigs, was developed from the sequence reads of two gerbera lines, using Trinity, TransAbyss, Velvet and SoapDenovo. Analysis of the quantified sequence reads revealed that 5,603 transcripts were differentially expressed: 2,057 up-regulated and 3,546 down-regulated. Sequence variant calling using GATK, SamTools and Freebayes revealed 580,141, 399,594 and 1,331,235 SNPs between the gerbera lines, respectively. These SNPs can be a valuable resource for developing molecular markers in gerbera breeding. 6. Evaluation of Lantana camara to identify sterile, non-invasive cultivars: Forty-five Lantana breeding lines were evaluated for their fruit production, pollen stainability and other traits. A number of the lines seem to be promising diploids or tetraploids for production of triploids from which sterile, non-invasive lantana can be identified. 7. Evaluation of tetraploids in ligustrum and nandina: Growers in the southeast U.S. are very interested in producing and offering sterile, non-invasive ligustrum and nandina cultivars. Tetraploid ligustrum and nandina lines were grown in the shadehouse or field, and their growth and development were evaluated. A few of them can be good parents for the production of triploids in these species.

    Publications

    • Type: Book Chapters Status: Published Year Published: 2018 Citation: Deng, Z. 2018. Caladium breeding. pp. 273-299. In: J.V. Huylenbroeck (ed.), Ornamental crops Handbook of plant breeding 11. Springer International Publishing AG, Switzerland. https://doi.org/10.1007/978-3-319-90698-0_12.
    • Type: Book Chapters Status: Published Year Published: 2018 Citation: Deng, Z. and K. Bhattarai. 2018. Gerbera breeding. pp. 407-438. In: J.V. Huylenbroeck (ed.) Ornamental crops, Handbook of plant breeding 11. Springer International Publishing AG, Switzerland. https://doi.org/10.1007/978-3-319-90698-0_17.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Bhattarai, K., W. Wang, Z. Cao, and Z. Deng. 2018. Comparative analysis of impatiens leaf transcriptomes reveal candidate genes for resistance to downy mildew caused by plasmopara obducens. International Journal of Molecular Science 19(7). pii: E2057. doi: 10.3390/ijms19072057.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Cao, Z., Y. Guo, Q. Yang, Y. He, M. Fetouh, R. M Warner, and Z. Deng. 2018. Genome-wide search for quantitative trait loci controlling important plant and flower traits in petunia using an interspecific recombinant inbred population of Petunia axillaris and Petunia exserta. G3: Genes, Genomes, Genetics. https://doi.org/10.1534/g3.118.200128.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Deng, Z. and N.A. Peres. 2018. ⿿Icicle⿿ ⿿ A white lance-leaved caladium cultivar for containers and shady landscapes. HortScience 53:1076-1079; doi:10.21273/HORTSCI13073-18.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Freyre, R., Z. Deng, and V.A. Zayas. 2018. Fruitless and semi-dwarf Ruellia simplex R13-5-3, R15-24-17, and R16-1-1. HortScience 53(10):1528-1533.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Liu, J., Z. Cao, Y. You, R. Zhong, and Z. Deng. 2018. Recent progress in caladium breeding and genetic research. Acta Horticulturae Sinica. 45(9):1791-1801. doi?10.16420/j.issn.0513-353x.2018-0214. http://www.ahs.ac.cn (in Chinese, with English abstract).
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Wang, W., Y. He, Z. Cao, and Z. Deng. 2018. Induction of tetraploids in impatiens (impatiens walleriana) and characterization of their changes in morphology and resistance to downy mildew. HortScience 53:925-931; doi:10.21273/HORTSCI13093-18.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Bhattarai, K. and Z. Deng. 2018. Improved gerbera transcriptome assembly using a combination of four assemblers. Abstract to 132nd American Society of Horticultural Science Annual Conference, Washington DC, July 31 ⿿ August 3, 2018. https://ashs.confex.com/ashs/2018/meetingapp.cgi/Paper/28579.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Deng, Z. 2018. Breeding and genetic research in cut-flower gerberas. Abstract to the American Society for Horticultural Science (ASHS) 2018 Annual Conference, Washington DC, July 30-August 3, 2018. https://ashs.confex.com/ashs/2018/meetingapp.cgi/Paper/28012.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Deng, Z., S.B. Wilson, G. Knox, and R. Freyre. 2018. Genetic sterilization of Lantana camara to produce infertitle, non-invasive cultivars. American Society for Horticultural Science (ASHS) 2018 Annual Conference, Washington DC, July 30-August 3, 2018. https://ashs.confex.com/ashs/2018/meetingapp.cgi/Paper/29234.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Xu, J. and Z. Deng. 2018. Progress in genetic sterilization of Lantana camara through ploidy manipulation. Abstract to the 131st Annual Meeting of the Florida State Horticultural Society. Ft. Lauderdale, June 10-12, 2018.


    Progress 10/01/16 to 09/30/17

    Outputs
    Target Audience:Commercial floricultural businesses (growers, nurseries, and landscapers), county extension agents, and researchers, and interested general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided technical and professional training for three graduate students, one undergraduate student, and one high school student. How have the results been disseminated to communities of interest?Results from this project were presented at the 130th Annual Meeting of the Florida State Horticultural Society, the 2017 American Society for Horticultural Science, the UF Caladium Research Forum (intended for caladium growers), and other outreach and extension events (such as the ploidy manipulation for plant breeding workshop and in-service training, the University of Florida's master gardener coordinator in-service skill training, and the 2017 FL AgExpo). Part of these results were published in scientific journals including HortScience, Horticulture Research, and the International Journal of Molecular Science. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? 1. Field trials of advanced caladium breeding lines: Six advanced caladium breeding lines were tested in a replicated field trial with four commercial caladium cultivars. The breeding lines were evaluated for plant growth, plant performance, sunburn tolerance, and tuber yields. In addition, 567 new breeding lines were evaluated in observational trials, resulting in approximately 400 advanced breeding lines for further trials in the next few years. Highly promising lines have been identified. Five advanced breeding lines were sent to commercial caladium growers and trialed in growers' fields. 2. Evaluation of caladium somaclonal variants: 24 caladium somaclonal variants were increased in the field. In the meantime, they were evaluated for plant growth, leaf color, and sunburn tolerance. With the availability of additional planting stock, these variants will be tested in replicated trials in the future. In addition, 50 somaclonal variants identified from the tissue culture liners of four commercial cultivars, 'Aaron', 'Carolyn Whorton', 'Freida Hemple', and 'White Christmas', were increased and evaluated in a shadehouse. Remarkable differences have been observed among these somaclonal variants. 3. Development and release of sterile, non-invasive lantana cultivars: 'Bloomify Red' and 'Bloomify Rose', two sterile, non-invasive lantana cultivars that were released in 2016, have been licensed by one major horticultural company. Major growers in Florida as well as other states are producing these two cultivars. Both cultivars are well received. Forty new lantana breeding lines were identified. Their ploidy level were determined, and their fruit production was determined by growing the lines in replicated field trials. A number of the lines seem to be promising diploids or tetraploids for production of triploids from which sterile, non-invasive lantana can be identified. 4. Induction and evaluation of tetraploids in ligustrum and nandina: Our survey indicated that growers in the southeast U.S. are very interested in producing and offering sterile, non-invasive ligustrum and nandina cultivars. A number of tetraploids were identified out of colchicine-treated seedlings. The tetraploids were grown in the shadehouse or field, and their growth and development were monitored. A few of them seem to be good as parents for production of triploids in these species.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Deng, Z., S.B. Wilson, X. Ying, and D.M. Czarnecki II. 2017. Infertile Lantana camara cultivars UF-1011-2 and UF-1013A-2A. HortScience 52(4):652-657.
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Cao, Z. and Z. Deng. 2017. De novo assembly, annotation, and characterization of root transcriptomes of three caladium cultivars with a focus on necrotrophic pathogen resistance/defense-related genes. International Journal of Molecular Sciences 18, 712. DOI:10.3390/ijms18040712.
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Cao, Z., S. Sui, Q. Yang, and Z. Deng. 2017. A single gene controls leaf background color in caladium (Araceae) and is tightly linked to genes for leaf main vein color, spotting and rugosity. Horticulture Research 4, Article number 16067. DOI:10.1038/hortres.2016.67.
    • Type: Other Status: Published Year Published: 2017 Citation: Deng, Z and S.B. Wilson. 2017. Bloomify" Red and Bloomify" Rose, two infertile Lantana camara cultivars for production and use in Florida. University of Florida/IFAS, EDIS Extension Fact Sheet ENH1280 .
    • Type: Other Status: Published Year Published: 2017 Citation: Deng, Z. 2017. Caladium cultivars Cosmic Delight, Fiesta and Hearts Desire. University of Florida/IFAS, EDIS Extension Fact Sheet ENH1281 .


    Progress 03/15/16 to 09/30/16

    Outputs
    Target Audience:Commercial floricultural businesses (growers, nurseries, and landscapers), county extension agents, and researchers, and interested general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided technical and professional training for five graduate students, one undergraduate student, one high school student, and 17 interns who graduated from college. How have the results been disseminated to communities of interest?Results from this project were presented at the 129th Annual Meeting of the Florida State Horticultural Society, the 2016 American Society for Horticultural Science, the 2016 International Conference on Genomes (Plant & Animal Genome XXIV), the 2016 Annual Conference of the Florida Exotic Pest Plant Council, the Florida Flower Trials, the 2016 Florida Landscape Show, the UF Caladium Research Forum (intended for caladium growers), and other outreach and extension events (such as Central Florida Present: New Ornamental Plants Updates, UF/IFAS South Central Green Team meeting, University of Florida 2016 Urban Landscape Summit, University of Georgia Institute of Plant Breeding, Genetics and Genomics, and the SCRI Meeting on Downy Mildew). Part of these results were published in scientific journals including HortScience, the Journal of the American Society for Horticultural Science, and the Plant Cell, Tissue and Organ Culture. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? 1. Field trials of advanced caladium breeding lines: Six advanced caladium breeding lines were planted in the caladium field, in three blocks with four widely grown commercial caladium cultivars. The breeding lines were evaluated for plant growth, plant performance, sunburn tolerance, and tuber yields. In addition, 1,100 new breeding lines were evaluated in observational trials, resulting in approximately 600 advanced breeding lines for further trials in the next few years. Dozens of highly promising lines have been identified. 2. Release one new caladium cultivar: Based on leaf color, plant performance and tuber yield in experimental plots as well as plant performance and tuber yield in growers' fields, one advanced caladium breeding line was selected and released as a new cultivar. 'UF-R1022' showed produced high quality pot plants and performed well in sunny and shady landscapes. Tubers of this new cultivar is resistant to moderately resistant to Fusarium tuber rot disease. 'UF-R1022' produces white lance-shaped leaves and is a good replacement of old cultivars such as 'White Wing'. 3. Morphological and cytological characterization of caladium somaclonal variants: Sixty somaclonal variants were identified among 550 tissue culture-derived plants of four caladium cultivars ('Aaron', 'Carolyn Whorton', 'Freida Hemple', and 'White Christmas'). These variants showed changes in plant size and vigor, leaf color, coloration pattern and shape, and ploidy level. The frequencies of these variant types varied among caladium cultivars and among mericlones of cultivars and ranged from 4.8% to 67.7%. 'White Christmas' was particularly prone to mutate and produce variant types. The frequencies of variant types among mericlones of two cultivars varied from 0% to 14.6%. Leaf tissues of somaclonal variants were sampled for nuclear DNA content determination. Approximately 63.3% of the variants contained 2% more, or 2% less, nuclear DNA. Chromosome counting was done for 31 variants. 4. Induction and characterization of tetraploids in impatiens: Morphological characterization showed that induced impatiens tetraploids produced thicker stems, larger leaves, and larger flowers, and had large stomata but lower densities of stomata. Interestingly, induced impatiens tetraploids had higher pollen stainability and significantly lower downy mildew disease severity and lower sporangia densities after artificial inoculation of spores of Plasmopara obducens, the causal agent of impatiens downy mildew. 5. Development and characterization of transgenic impatiens: Multiple bud cultures of the impatiens cultivar Super Elfin Lipstick was co-cultivated with an Agrobacterium tumefaciens strain carrying the Arabidopsis NPR1 gene, as well as the GFP and the NPTII genes, followed by kanamycin selection and visual examination of the presence of green fluorescence under a stereo microscope. Ten transgenic lines were obtained. A good portion of the transgenic lines showed some changes in days to flower, flower number, and/or pollen production and stainability. Two lines produced more flowers per plant. Several lines showed improved resistance to downy mildew in leaf disc and in-vivo inoculation assays. 6. Releasing sterile, non-invasive lantana cultivars: Two lantana cultivars were released. Both cultivars were male and female infertile and didn't hybridize with native lantana in hand pollination. They demonstrated excellent container and landscape performance. Their inflorescences rarely produced any viable seeds.

    Publications

    • Type: Book Chapters Status: Published Year Published: 2016 Citation: Deng, Z. 2016. Breeding for disease resistance in florists crops, pp 1-31. In: R.J. McGovern and W.H. Elmer (eds.). Handbook of Plant Disease Management. Handbook of Florists Crops Diseases. Springer International Publishing, Switzerland (invited, in press). DOI: 10.1007/978-3-319-32374-9_4-1.
    • Type: Journal Articles Status: Published Year Published: 2016 Citation: Cai, X. and Z. Deng. 2016. Thidiazuron promotes callus induction and proliferation in Caladium �hortulanum Birdsey UF-4609. Propagation of Ornamental Plants 16(3):90-97.
    • Type: Journal Articles Status: Published Year Published: 2016 Citation: Cao, Z., S. Sui, Q. Yang, and Z. Deng. 2016. Inheritance of rugose leaf in caladium and genetic relationships with leaf shape, main vein color and leaf spotting. Journal of the American Society for Horticultural Science 141(5):527-534.
    • Type: Journal Articles Status: Published Year Published: 2016 Citation: Cao, Z., S. Sui, X. Cai, Q. Yang, and Z. Deng. 2016. Somaclonal variation in Red Flash caladium: Morphological, cytogenetic and molecular characterization. Plant Cell, Tissue and Organ Culture: Journal of Plant Biotechnology 126(2):269-279. DOI: 10.1007/s11240-016-0996-3.
    • Type: Journal Articles Status: Published Year Published: 2016 Citation: Deng, Z., B.K. Harbaugh, and N.A. Peres. 2016. Cosmic Delight, Fiesta, and Hearts Desire  Three caladium cultivars. HortScience 51(6):766-771.
    • Type: Journal Articles Status: Published Year Published: 2016 Citation: Fetouh, M.I., A. Kareem, G.W. Knox, S.B. Wilson, and Z. Deng. 2016. Induction, identification and characterization of tetraploids in Japanese privet (Ligustrum japonicum). HortScience 51(11):1371-1377.
    • Type: Journal Articles Status: Published Year Published: 2016 Citation: Rosanna, F., Z. Deng, G. Knox, and V. Zayas. 2016. Fruitless Ruellia simplex R12-2-1 (Mayan Compact Purple). HortScience 51(8):1057-1061.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Wang, W., Z. Deng, and A. Palmateer. 2015. Impatiens downy mildew: Pathogens, management options, and genetic resistance. Proc. Fla. State Hort. Soc. 128:206-209.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Bhattarai, K., W. Wang, and Z. Deng. 2016. Sequencing and analysis of leaf transcriptomes of impatiens cultivars differing in downy mildew resistance. HortScience 51(9):S280.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Bhattarai, K., Z. Cao, and Z. Deng. 2016. Sequencing and analysis of the transcriptomes of young ovaries of lantana. HortScience 51(9):S281.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Cao, Z. and Z. Deng. 2016. Karyotypic variation among somaclonal variants of caladium (Caladium �hortulanum). Plant & Animal Genome Conference XXIV, San Diego, CA, Jan. 9-13, 2016. https://pag.confex.com/pag/xxiv/webprogram/Paper20405.html.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Cao, Z., Y. Guo, Q. Yang, Y. He, R.M. Warner, and Z. Deng. 2016. QTL identification for plant and flower traits in petunia using recombinant inbred lines and SNP markers. Plant & Animal Genome Conference XXIV, San Diego, CA, Jan. 9-13, 2016. https://pag.confex.com/pag/xxiv/webprogram/Paper20232.html.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Cao, Z. and Z. Deng. 2016. De novo assembly, annotation, and characterization of root transcriptomes of caladium (Caladium �hortulanum). HortScience 51(9):S304.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Cao, Z., Y. Guo, Q. Yang, Y. He, M. Fetouh, R.M. Warner, and Z. Deng. 2016. QTL identification for plant and flower traits using interspecific recombinant inbred populations derived from Petunia axillaris, P. exerta, and P. integrifolia. HortScience 51(9):S303-304.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Deng, Z., D.M. Czarnecki II, X. Ying, S.B. Wilson, R. Freyre, and G.W. Knox. 2016. Progress in assessing and controlling the invasive potential of Lantana camara. Florida Exotic Pest Plant Council 2016 Annual Conference Program Book, page 15-16. Melbourne, FL, March 9-11, 2016.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Deng, Z., D.M. Czarnecki II, X. Ying, S.B. Wilson, R. Freyre, and G.W. Knox. 2016. Developing and selecting sterile, non-invasive Lantana camara cultivars. 129th Annual Meeting of the Florida State Horticultural Society Abstracts. Stuart, FL, June 12-14, 2016.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Deng, Z., J. Polston, and M. Kane. 2016. Progress towards rejuvenating caladium cultivars through tissue culture, pathogen eradication, and genetic testing. 129th Annual Meeting of the Florida State Horticultural Society Abstracts. Stuart, FL, June 12-14, 2016.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Freyre, R., A.M. Smith, C. Reinhardt-Adams, Z. Deng, G.W. Knox, and S.B. Wilson. 2016. Control of invasive�Ruellia simplex�by herbicide treatments in natural areas and breeding sterile cultivars. Program archive of the 2016 American Society for Horticultural Science Annual Conference, Atlanta, GA, August 7-11, 2016. HortScience 51(9):S80.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: He, Y., W. Wang, Z. Cao, and Z. Deng. 2016. Resistance to downy mildew caused by�Plasmopara obducens�in impatiens�at different growth stages. HortScience 51(9):S281.