Progress 10/01/19 to 09/30/20
Outputs
Target Audience:Professional peers: Distribution of BBTV-resistant banana germplasm to UH Cooperative Extension Office, Molokai, HI, for field trial and propagation (April 2020) Commercial tropical fruit growers: Distribution of BBTV-resistant banana germplasm to cooperating members of Hawaii Tropical Fruit Growers Assn. for variety trials on Kauai, Molokai, Maui, and Hawaii (March 2020) Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?Objective 1. Survey the banana test plants at the end of the 2nd year of the Waimanalo field trial for visual BBTV symptoms, and conduct PCR or ELISA assays to confirm the presence of virus. Objective 2. Propagate remaining Carica x Vasconcellea intergeneric hybrids and ship to USDA National Clonal Germplasm Repository in Hilo, HI, for safe keeping. Objective 3. Distribute the remaining BBTV-resistant banana clones to cooperating extension agents and members of the Hawaii Tropical Fruit Growers association.
Impacts
What was accomplished under these goals?
Objective 1. No progress. Objective 2. No progress. Objective 3. Tissue cultured banana clones with resistance to banana bunchy top virus were shipped to cooperating extension agents and members of the Hawaii Tropical Fruit Growers association on the neighbor islands of Kauai, Molokai, Maui, and Hawaii for evaluation in their field trials.
Publications
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Progress 10/01/17 to 09/30/18
Outputs
Target Audience:Professional peers, graduate students: - 5th International Symposium on Papaya, Merida, Mexico. (Oct. 2017) - Invited presentation, Yermanos Lecture at Univ. of California, Riverside, CA. (May 2018) - TPSS Dept. Seminar, UH Manoa, Honolulu, HI. (Sept. 2018) Commercial tropical fruit growers and members of the general public: - banana variety taste trial for growers, Kona, HI (Jan 2018) - banana taste trial for general public at Variety Showcase event, Honolulu. (March, 2018) - banana taste trial for supermarket customers, Kona, HI (May, 2018) - banana variety tasting event for general public at Hawaii Farm Fair, Kualoa Ranch, Oahu. (Aug. 2018) - Hawaii Tropical Fruit Growers Assn. (Sept. 2018) Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?Information about the BBTV-resistant banana clones has been transmitted to tropical fruit growers, supermarket customers, and the general public through a technical presentation at the Hawaii Tropical Fruit Growers annual meeting (Sept 2018), through consumer taste preference tests involving small target groups (Jan, March, May 2018), and through general information and tasting sessions at the Hawaii Farm Fair (Aug 2018). Information about the more basic research project involving intergeneric hybridization among papaya and wild relatives was also presented at the Hawaii Tropical Fruit Growers annual meeting (Sept 2018) and to a group of international horticulture researchers at the 5th International Symposium on Papaya (Oct 2017) (see Other Products). What do you plan to do during the next reporting period to accomplish the goals?Objective 1: The field planting to validate the BBTV resistance of the selected clones relative to current commercial varieties will be installed atWaimanalo in the first quarter of 2019. Objective 2. Research efforts will be directed toward continued clonal propagation of the existing intergeneric Carica x Vasconcellea hybrids and allotetraploid creation through meristem treatment with the mitotic inhibitor oryzalin. A new set of a dozen clonal hybrids is being readied for oryzalin treatment under greenhouse conditions, which will be more favorable for rapid meristem cell division than conditions in the lab, where previous attempts at chromosome doubling were unsuccessful. Oryzalin-treated hybrids will be evaluated by flow cytometry to determine the success of the new treatment methods. Objective 3. We will continue to conduct taste preference trials recording reactions of growers, market customers, and general public to the BBTV-resistant banana clones, when opportunities arise.
Impacts
What was accomplished under these goals?
Objective 1: The four BBTV-resistant banana clones, including Pisang Awak (ABB) varieties 'Kayinja' and 'NPV' and Gros Michel (AAA) clones 'Cocos' and 'Highgate', that were placed in tissue culture last year by cooperators in CTAHR/PEPS Dept., using a mericloning procedure that eliminates BBTV in the propagules, have had several setbacks. Most recently (August 2018), a malfunctioning incubator destroyed materials that were originally going to provide virus-free test plants for the Waimanalo demonstration trial (managed by GoFarm Program) and for smaller demonstration plantings on outer islands (managed by Hawaii Tropical Fruit Growers Association) by summer 2018. The mericloned cultures are being restored, but due to delays, the TC plants will not be available for program use until 2020. They may be used as source materials for later public distribution after completion of trials. The plants required for the Waimanalo trial have been purchased from Banana Source Hawaii, operated by Gabriel Sachter-Smith, and the planting date that was projected for early fall 2018 is now delayed until spring 2019. The proposed Waimanalo demonstration trial for farmer/chef field days is also designed as a replicated experiment to validate the BBTV resistance and productivity of the selected clones ('Cocos', 'Highgate', 'Kayinja', and NPV) relative to two standard commercial clones ('Williams' Cavendish and 'Dwarf Brazilian'). The wild clone of Musa acuminata ssp. malaccensis, identified by this project as being BBTV-resistant and of potential value for banana breeding, was sent in late September 2017 to Bioversity International, which maintains the world Musa germplasm in vitro collection at Leuven, Belgium. Objective 2: Vigor of the Carica papaya x Vasconcellea stipulata hybrids declined in fall 2017 in the greenhouse, and they eventually died without flowering. Project efforts have focused on propagating and maintaining the remaining intergeneric Carica x Vasconcellea hybrids, and on developing more effective chromosome doubling methods for allotetraploid creation. Vegetative cloning by rooting 6" stem cuttings or leafy tip cuttings of greenhouse-grown V. goudotiana or C. papaya x V. goudatiana F1s has been nearly uniformly successful. Propagative materials were treated with 500 ppm IBA for 5 minutes, and leafless stem cuttings were potted in moist Sunshine #4 potting mix, while leafy tip cuttings were placed in water or Q-Plugs, and both were enclosed in plastic Ziploc bags to maintain humidity. Rooting and new vegetative growth occurred within 1-2 months. Cloning V. pubescens, C. papaya x V. pubescens F1 plants, or C. papaya x V. x heilbornii F1 plants has been slower and less successful, especially in water, but some cuttings have been successfully rooted. Previous attempts to produce allotetraploid hybrids by applying oryzalin and dimethyl sulfoxide (DMSO) in an agar gel to apical meristems produced only mixoploid plants that quickly reverted to diploidy. In April 2018, two small clonal cuttings each of the three remaining hybrids (C.p. x V. goudotiana, C.p. x V. pubescens, and C.p. x V. x heilbornii) were treated for three days with 0.5% (A.I.) oryzalin and 1% DMSO without the gelling agent, using cotton balls to keep the apex meristem continuously in contact with the liquid treatment. The treated plants were placed in a saturated chamber to prevent evaporation of the oryzalin. We think this liquid approach will improve penetration of oryzalin through protective tissues to the meristematic cells, which may have been unreached by the more viscous gel. Some obvious changes in subsequent leaf morphology have been noted in the treated plants, but no necrosis. Ploidy level will be determined by flow cytometry at a later time, and more oryzalin treatments are planned for a recently produced set of clonal materials. Objective 3: Taste trials were conducted on the Big Island by collaborator Ken Love, Executive Director of Hawaii Tropical Fruit Growers Association, from fruits harvested at our Kona Station field plot in January and May, 2018. The January trial involved 9 growers evaluating the clones 'Williams', 'Dwarf Brazilian' and 'Kayinja', while the May trial surveyed the responses of 14 grocery store customers tasting the same clones. A March 2018 taste trial was conducted by Richard Manshardt at Kapiolani Community College as part of the Variety Showcase farm-to-table event, involving 28 participants evaluating the clones 'Williams', 'Dwarf Brazilian', 'Kayinja' and 'NPV', all obtained from local sources. A rating scale [1 (poor) to 5 (excellent)] was used to evaluate overall quality, and comments about flavor, texture and flesh color were collected. Although the results revealed statistically significant differences in only one trial, informative trends were observed. 'Kayinja' was rated highest in two of the three trials and second-best in the third trial, relative to the standard commercial clones 'Williams' and 'Dwarf Brazilian'. In the March trial that evaluated both Pisang Awak clones ('Kayinja' and 'NPV'), participants could not distinguish between them. 'Williams' consistently had the poorest quality rating. These initial results are interesting in suggesting that the quality of the Pisang Awak clones may be acceptable to most consumers in direct competition with the current commercial clones.
Publications
- Type:
Journal Articles
Status:
Under Review
Year Published:
2018
Citation:
Hoover, G. and Manshardt, R. 2018. Intergeneric hybridization of Carica papaya with Vasconcellea wild relatives. Acta Horticulturae.
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