Progress 04/01/98 to 12/31/03
Outputs
1. To develop cultivars for the sweetpotato industry with the following characteristics: improved insect resistance, high yield, multiple disease resistance, and good storage. Superior baking, canning, and processing quality are additional desired characteristics. This project had two patented releases during this period: Bienville and 96-117. 2. Improve sweetpotato breeding methodology. New approaches to early line screeing (flooding tolerence) were initiated. 3. Inheritance of pest resistance in sweetpotato. New approaches were studied to identify trait-linked molecular markers without mapping populations. 4. The use of paternity analysis in sweetpotato to identify male paternity in superior offspring. Several papers were published on this topic and the foundation laid to identify paternity in open pollinated nurseries. 4. Molecular characterization of the sweetpotato genome. Research was initiated to use DNA microarrays in sweetpotato as a means of understanding
mutation events and development of fleshy storage roots.
Impacts
Release of new cultivars for the sweetpotato industry. Newly released Bienville provides yields approximating Beauregard with southern root-knot nematode resistance. Beauregard lacks this resistance. Louisiana producers in Morehouse Parish have soils infested with southern root-knot nematode. They can eliminate the need for soil fumigants by growing Bienville. California producers have also expressed an interest in this variety. The breeding program strives to enhance germplasm to achieve higher levels of pest resistance in sweetpotato. For instance, a breeding population is being developed to enhance levels of resistant to rhizopus soft rot, an important post-harvest problem. High levels of resistance could eliminate the need for the fungicide Botran sprayed on roots before shipping. Greater understanding of the genetics of sweetpotato is an important aspect of the program. Our initial work on microarrays in sweetpotato is to better understand the high rate of
mutations found in sweetpotato. Over time most varieties decline in yield due to an accumulation of mutations. This work will enable us to develop methods to identify and maintain "type" selections of a given cultivar to maintain high yield and quality. Higher quality sweetpotato with value-added potential is a final objective. Lutein is an important nutrient found in sweetpotato leaves, a previously unmarketable resource. Collaborative research is underway to understand the genetic range of lutein in sweetpotato leaves and to identify an efficient means of extraction.
Publications
- Mcharo, M., E. Bush, D. La Bonte, C. Broussard, and L. Urbatsh. 2003. Molecular and morphological investigations of ornamental liriopogons. J. Amer. Soc. Hort. Sci. 128: 575-577.
- Villordon, A.Q., J.M. Cannon, H.L. Carroll, J.W. Franklin, C.A. Clark, and D.R. La Bonte. 2003. Sweetpotato Beauregard mericlones vary in yield, vine characteristics, and storage root size and shape attributes. HortScience 38:1089-1092.
- La Bonte, D.R., J.M. Cannon, C.A. Clark, A.Q. Villordon, P.W. Wilson, A.H. Hammond, and R.N. Story. 2003. Bienville sweetpotato. HortScience 38:473-474.
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Progress 01/01/02 to 12/31/02
Outputs
The primary objective of this project is cultivar development. L94-96 was released as Bienville in 2002. A patent was applied for in 2002. It has good disease tolerance (root knot nematode resistance),yields well, and has some tolerance to weeds and souring in flooded fields. It performed well in Louisiana in 2002. Additional advanced lines were tested and new germplasm generated in nurseries for cultivar development and for resistance to rhizopus soft rot. Seed also was generated from a nursery targeting insect resistance. Research was completed on genetic diversity of sweetpotato collected in Papua New Guinea and published. A paper was published on paternity analysis in sweetpotato. This completed the research in this area. Micro-array based research was initiated. Plant material for this research was grown and processed in 2002. This represents a new approach to investigating mutations in sweetpotato via differential expression of transcripts in clonal mutants. It
also represents a means of identifying R (resistance) genes in sweetpotato.A grant was submitted to support this research. Discriminant analysis was further examined as a means of identifying important trait-linked DNA markers in sweetpotato. Dry matter, sugar content, and carotene content were the major traits used to examine this approach to marker identification.
Impacts
Breeding: develop new sweetpotato cultivars with improved insect resistance, high yield, multiple disease resistance, and good storage. No private company breeds sweetpotato. Mutation research: mutations are implicated in yield and quality decline in varieties. Micro-arrays may enable us to identify specific factors that cause mutations in sweetpotato and identify key genes useful in enhancing resistance to pests. Genetics: identifying paternity in sweetpotato may enable us to combine two desirable parents that tend to generate a high proportion of superior progeny. Discriminant analysis is a practical means of linking DNA markers to important traits-facilitating breeding efforts. Other approaches are cumbersome given sweetpotato hexaploid genetics.
Publications
- La Bonte, D.R. 2002. Molecular biology in sweetpotato genetics: a means of progress, p. 21-29. In: T. Ames (ed.). Proceedings of the first international conference on sweetpotato: Food and health for the future, Lima, Peru. Acta Horticulturae 583.
- Buteler, M.I., D.R. La Bonte, R.L. Jarret, and R.E. Macchiavelli. 2002. Microsatellite-based paternity analysis in polyploidy sweetpotato. J. Am. Soc. Hort. Sci. 127:392-396.
- Fajardo, D.S., D.R. La Bonte, and R.L. Jarret. 2002. Identifying and selecting for genetic diversity in Papua New Guinea sweetpotato, Ipomoea batatas (L.) Lam. Germplasm collected as botanical seed. Genet. Resour. Crop Evol. 49:463-470.
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Progress 01/01/01 to 12/31/01
Outputs
The primary objective of this project is cultivar development. L94-96 will be released. It has good disease tolerance (root knot nematode resistance),yields well, and has some tolerance to weeds and souring in flooded fields. It does show senescence in storage. Plant production is weak from bedded roots. Research was completed on genetic diversity of sweetpotato collected in Papua New Guinea. Sweetpotato in Papua New Guinea is not genetically diverse, as is commonly assumed. The goal was to develop a core of genotypes representative of the larger collected population. A collaborative paper was published on sweetpotato weevil resistance. New micro-array based research was initiated. This represents a new approach to investigating mutations in sweetpotato via differential expression of transcripts.
Impacts
Breeding: develop new sweetpotato cultivars with improved insect resistance, high yield, multiple disease resistance, and good storage. No private company breeds sweetpotato. Mutation research: mutations are implicated in yield and quality decline in varieties. Micro-arrays may enable us to identify specific factors that cause mutations in sweetpotato. Genetics: identifying paternity in sweetpotato may enable us to combine two desirable parents that tend to generate a high proportion of superior progeny.
Publications
- Mao, L., R.N. Story, A.M. Hammond, and D.R. La Bonte. 2001. Effect of sweetpotato genotype, storage time and production site on feeding and oviposition behavior of the sweetpotato weevil, Cylas formicarius (Coleoptera:Apoinidae). Florida Entom. 84:259-264.
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Progress 01/01/00 to 12/31/00
Outputs
The primary objective of this project is cultivar development. L94-96 is being considered for release. It has good disease tolerance, yields well, and has some tolerance to weeds and souring in flooded fields. It does show some senescence in storage. This is under evaluation. A paper was published on changes in carbohydrate composition in developing sweetpotato. The goal was to characterize the physiology of highly sweet sweetpotato. This is an important trait we strive to enhance. A paper was published on plant production using black polyethylene row covers. This method increased plant production, but reduced quality in comparison to controls.
Impacts
Develop new sweetpotato cultivars with improved insect resistance, high yield, multiple disease resistance, and good storage. No private company breeds sweetpotato.
Publications
- La Bonte, D.R., D.H. Picha, and H.A. Johnson. 2000. Carbohydrate-related changes in sweetpotato storage roots during development. J. Am. Soc. Hort. Sci. 125:200-204.
- La Bonte, D.R., J.R. Schultheis, D.W. Monks, and A.Q. Villordon. 2000. Effect of black polyethylene tunnel covers on plant production and quality of sweetpotato transplants. HortScience 35:202-204.
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Progress 01/01/99 to 12/31/99
Outputs
The primary objective of this project is cultivar development. L94-96 is strongly being considered for release. It has excellent disease resistance, yields well, and has tolerance to rice flat sedge. We are also finding that it has tolerance to souring in flooded soil. A release/drop decision will be made in the fall of 2000 based on more extensive testing this summer and grower interest. A paper was published on the effect of canopy type on weed competition. Another paper was published on microsatellite sequences in sweetpotato. Sweetpotato is unique in that it has a high proportion of gross inserts and deletions, i.e., alleles vary expectedly in the repeat regions and unexpectedly in flanking sequences. Current research is focused on developing a molecular marker fingerprint technique to differentiate clones within the same variety. This will lead to an effective method of maintaining varieties without decline.
Impacts
Develop new sweetpotato cultivars with improved insect resistance, high yield, multiple disease resistance, and good storage. Superior baking, canning and processing quality are additional characteristics stressed in the program. No private company breeds sweetpotato.
Publications
- Buteler, M.I., R.L. Jarret, and D.R. La Bonte. 1999. Sequence characterization of microsatellites in diploid and polyploid Ipomoea. TAG 99:123-132.
- La Bonte, D.R., H.F. Harrison, and C.E. Motsenbocker. 1999. Sweetpotato clone tolerance to weed interference. HortScience 34:229-232.
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Progress 01/01/98 to 12/31/98
Outputs
The main objective of this project is the development and release of sweetpotato cultivars. Advanced line L 94-96 shows much promise and likely will be released in 1999. This line has superior disease resistance, good yield, and allelopathic properties, i.e., competes well against weed species. The only flaw is that the roots maybe difficult to separate from the vines. Studies are planned this year to evaluate yield of virus tested plants of L 94-96 for the first time and the root separation problem. A study on sweetpotato competitive ability against weeds was completed and is in press. Another paper is in press documenting the non-repetitive nature of DNA microsatellites in sweetpotato. Results show that alleles for a given microsatellite loci vary by the number of repeat sequences (expected). They also have sizable additions of non-repetitive DNA sequences (unexpected). It is not clear why microsatellites are so different in sweetpotato, but these results support
our findings that microsatellites are not useful as a DNA marker system in sweetpotato.
Impacts
(N/A)
Publications
- Buteler, M.I., R.L. Jarret, and D.R. La Bonte. 1999. Sequence characterization of microsatellites in diploid and polyploid Ipomoea. TAG (in press).
- La Bonte, D.R., H.F. Harrison, and C.E. Motsenbocker. 1999. Sweetpotato clone tolerance to weed interference. HortScience (in press).
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