Progress 10/01/04 to 09/30/07
Outputs
OUTPUTS: Mutation induction using irradiation is a useful method for creating new varieties of ornamental plants that are vegetatively propagated. The LD50 dosage, generally accepted as the optimum irradiation dosage for the purpose of creating new varieties, was reported for four varieties in the previous reporting period. Building on those findings, radiation dosages of 0.0, 5.0, 7.5, 10.0, 12.5, 15.0 and 20.0 grays of gamma radiation, using a Cesium-137 source, were given to 488 cuttings of D. Santa Rosa of which 28 mutants (5.7%) were kept for observation, 982 cuttings of D. Massangeana of which 25 mutants (2.5%) were kept, 862 cuttings of D. Victoriae of which 51 mutants (5.9%) were kept, 356 cuttings of D. Warneckii of which 7 mutants (2.0%) were kept, 605 cuttings of D. Janet Craig of which 9 mutants (1.5%) were kept, and 210 cuttings of the hybrid D. x Masseffiana of which 3 mutants (1.4%) were kept. Of the 3,503 cuttings of 6 Dracaena varieties that were irradiated with
gamma rays, was probably about 20%, with the majority of the mutants being undesirable (loss of original variegation, total loss of chlorophyll, etc.). Desirable mutations, with new colors and patterns of variegation, totaled 123, about 3.4% of all cuttings treated. Of the desirable mutations, 33 have grown large enough for field planting, and are under observation in a field plot. Radiation treatments of 0.0, 2.5, 5.0, and 7.5 grays were also made on plantlets and callus of D. Lisa in tissue culture. These materials have not died, but except for the control they do not appear to be growing. The production of an oryzalin induced tetraploid D. Lisa was previously reported. A cutting propagation was made. These plants are slow growing and may not be useful, except for future breeding of triploid progeny. Emily S. Teng wrote a Masters thesis titled Foundations for a Long Term Dracaena Breeding Program: Flower Induction, Irradiation and Polyploidization. She and her research was TSTAR
funded.
PARTICIPANTS: Ken Leonhardt, Emily Teng (graduate student), John Griffis, Andrew Kawabata, Joanne Lichty (technician in Hilo) and Ronald Matsuda (technician on the UH Manoa campus) all contributed to this project.
TARGET AUDIENCES: The target audience is the Hawaii ornamental plant industry, and the growers who participate in this industry.
PROJECT MODIFICATIONS: There are no major changes. More emphasis is now placed on developing new varieties using radiation technology than breeding because there has been considerable success obtaining interesting new radiation induced mutations, and very limited success from breeding.
Impacts
Dracaena were ranked 2nd in sales among all foliage and 3rd among all floriculture and nursery products in Hawaii in 2006. Some of the desirable, radiation induced mutations will provide Hawaii growers with exciting new varieties, and hopefully expanded market opportunities.
Publications
- Teng, E.S. and Leonhardt, K.W. 2007. In vitro and in vivo polyploidization of Dracaena with oryzalin. VI International Symposium on New Floricultural Crops, Madeira. Published abstract.
- Teng, E.S. and Leonhardt, K.W. 2007. Optimum irradiation dosage of unrooted Dracaena cuttings for mutation induction. VI International Symposium on New Floricultural Crops, Madeira. Published abstract.
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Progress 10/01/05 to 09/30/06
Outputs
Several hundred cross pollinations between Dracaena and Cordyline flowers made in attempt to create an intergeneric hybrid have resulted in 12 seeds which are still under observation. Several hundred cross pollinations between different Dracaena species were also made in attempt to make an interspecific hybrid. About 25 seeds have resulted from these crosses and it seems that one is possibly an interspecific hybrid (D. xmasseffiana x D. fragrans). Flower induction experiments using GA3 and cold temperature treatments have had limited success. GA3 and cold temperature treatments were successful in inducing D.xmasseffiana to flower more frequently at higher concentrations. However, in the other species and varieties tested, no additional flowering occurred due to the treatments. Pollen germination using Brewbaker and Kwack's medium were conducted on several species. Freshly opened anthers were teased open in a drop of media on a slide and placed in a covered Petri dish
containing moistened filter paper. The Petri dish was placed under lights overnight and the next day at least 300 pollen cells were counted and germination determined. The germination percentages for D. fragrans 'Massangeana', D. surculosa, D. deremensis 'Santa Rosa' and 'Warneckei', D.xmasseffiana, and D.xmasseffiana MREC 98-12 were 22.63, 10.6, 3.95, 33.4, 8.4 and 24.3%, respectively. This information will help with any further cross pollination efforts. The mutant form of D.xmasseffiana (D.xmasseffiana MREC 98-12) was confirmed as a tetraploid with chromosome counts showing it has 78 chromosomes and the diploid form has 39. Dracaena deremensis 'Lisa' in vitro cultures were initiated and callus tissue induced on the bases of stem explants. Callus were treated with 2 concentrations(0.005% and 0.01%) and 2 durations(24 and 48 hours) of oryzalin for a total of 4 treatments. Oryzalin has chromosome doubling capabilities. Calli were placed on shoot regeneration media and new plantlets
were formed. To test for polyploidization, flow cytometry was conducted on leaf tissues and one plant was found to be a tetraploid. This plant has some morphological differences from untreated diploid plants, including smaller leaves and shorter internode length. The plant will be observed for suitability as a new cultivar. Newly forming axillary buds of Dracaena deremensis 'Santa Rosa' field plants were treated with oryzalin at 2 concentrations(0.005% and 0.01%) and 2 durations(24 and 48 hours) for a total of 4 treatment to attempt to created a tetraploid. After buds grew to size, they were tested for polyploidization using flow cytometry and one mixoploid was found. Four varieties of unrooted Dracaena cuttings were irradiated with Cesium 137 gamma rays and the LD50 dosage was determined. The LD50 dosages for D. deremensis 'Santa Rosa', D. fragrans 'Massangeana' and 'Victoriae', and D.xmasseffiana were found to be 18.07, 13.58, 20.87, and 23.29 Gy, respectively. Percent mutation
ranged from 0% to 55% with the most common type being chlorophyll mutations such as all yellow or all green leaves. Large numbers of cuttings can now be irradiated in the LD50 range to induce more mutations.
Impacts
Dracaena is a highly important nursery product in Hawaii, ranking 2nd among all floriculture and nursery products in 2005. New cultivars to introduce to the market would help the Hawaii foliage industry cater to consumer's ever changing preferences and keep sales up. This project used mutation induction to create plants with different morphology and different variegation. If these plants are suitable to introduce to the market, they could help Hawaii's growers by giving them unique products no one else has and putting them on the cutting edge of the foliage market.
Publications
- No publications reported this period
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Progress 10/01/04 to 09/30/05
Outputs
Several hundred pollinations between different Dracaena have been attempted. Out of these, only 2 fruit have been obtained, which are a result of a cross between D. angustifolia 'Honoriae' x D.xmasseffiana MREC 98-12. These two seeds have not yet germinated. Dracaena flower only once a year and this is a major limiting factor in hybridization, so an efficient method of out of season flower induction is desired. Additional flower induction experiments have been attempted using cold temperature treatments since the last report. Plants were placed in cold temperature chambers for 7 nights (5 PM till 8 AM). D. deremensis 'Janet Craig', D. fragrans 'Massangeana', D. fragrans 'Santa Rosa', and D.xmasseffiana were treated at temperatures of 6, 9, 12, and 15 degrees Celsius. This experiment attempted to simulate natural conditions in which temperatures are warmer during the day and cooler at night and thought would be a more effective method to induce flowering. However, none
of the plants had any flowering response. A second experiment is in progress. Plants are being subjected to 20 and 40 days in the cold temperature chambers. D. fragrans 'Massangeana', D.xmasseffiana, D. surculosa, D. fragrans 'Massangeana Compacta' and D. 'Fantasy' are being treated at 12 and 15 degrees Celsius. Chromosome counts have been conducted on several species and cultivars of Dracaena to confirm their ploidy levels. The numbers were found to be D.xmasseffiana (39), its mutant form D.xmasseffiana MREC 98-12 (78), and their parents D. surculosa (40) and D. fragrans 'Massangeana' (38). This confirms our earlier speculations that the mutant form D. xmasseffiana MREC 98-12 is a tetraploid form of D. xmasseffiana. A good medium for the induction of callus in Dracaena has been tested and found to be suitable. A medium for regeneration of shoots is currently being tested. When suitable media formulations are determined, the callus will be treated with oryzalin to induce polyploidy.
Induced mutations using irradiation treatments is in progress. Unrooted cuttings 5 inches in length were irradiated with x-rays with dosages ranging from 0 to 150 Gy. D. fragrans 'Santa Rosa', D. deremensis 'Warneckei', D. deremensis 'Janet Craig', D. fragrans 'Massangeana', D. concinna, D. fragrans 'Victoria', and D. xmasseffiana were treated in this experiment. Observations to date have shown that cuttings exposed to increasing dosages have decreased rooting and shoot development. Also, several different color and variegation mutations have occurred, including conversion to all green leaves, all white (albino) leaves, and different variegation patterns. Seeds of D. concinna and D. fragrans 'Massangeana' have also been irradiated with X-rays ranging in dosage from 0 to 200 Gy. These seeds have yet to germinate. Permission has been obtained to use an irradiator which exposes the plants to gamma ray irradiation. This is generally a more efficient method of mutation. A similar
experiment to that of the X-ray irradiation is planned, with unrooted cuttings 5 inches in length to be exposed to 0 to 500 Gy dosages and then rooted. Observations will be made on root and shoot development.
Impacts
Dracaena were ranked 2nd in sales among all foliage and 3rd among all floriculture and nursery products in Hawaii in 2004. Despite this economic importance, however, new varieties are not being created and introduced into the market. With ever changing consumer preferences, the Hawaii Nursery industry must also change to keep their sales up. This project aims to create new Dracaena cultivars for the Hawaii foliage industry through a variety of methods. Characteristics such as new colors, new and unique variegation, and new and unique morphology are desired. Traditional breeding through cross pollination, induction of polyploidy using in vivo and in vitro methods, and induced mutations through irradiation, both x-ray and gamma ray, are being employed to attempt to create these new characteristics.
Publications
- No publications reported this period
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