Progress 09/28/05 to 09/27/10
Outputs
OUTPUTS: Crosses are continued to be made between SunUp and the slow ripening line 4-16. The F1 seed from the first crosses are now being field planted. When theses F1 plants start flowering, selected progeny will be backcrossed to SunUp and the slow ripening trait selected for in the progeny. The slow ripening trait has shown itself to be dominant in previous crosses. We are continuing to select a line that has stripped fruit. The current line is still segregating. This line could be used to separate the fruit in the market. Laie Gold transgenic papayas were selected by a commercial grower and micropropagated. The three field tests were conducted in Kahaluu, Laie, and Kahuku on Oahu. Growth data were collected from all three fields; however, yield data were obtained only from Laie but not from Kahuku due to the flood in early 2006. Plants were micropropagated and cuttings made for the replacement field that was established in July 2010. Clonally propagated Rainbow and Laie Gold hermaphrodites were also sold to growers on Oahu and Hawaii. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Surveys of papaya fields on the Big Island showed that white peach scale infestation was widespread, estimating 90 percent of all trees were infested with females scales and about a quarter of all trees had high levels of infestation. Density of the different stages of white peach scale was significantly higher during summer months. Two species of predatory beetles were observed attacking adult female and immature scales. Cybocephalus nipponicus appears to be much more common than Rhyzobius spp. in the papaya fields sampled. Parasitism rates by Anagyrus loecki ranged from 3.3 to 20 percent in adult females white peach scale whereas parasitism on second and third instars was lower than 5 percent. No parasitism was observed in first instar white peach scale. The most common insecticides used to control white peach scale in Hawaii are malathion, imidacloprid, buprofezin, and azadirachtin. The toxicity testes showed that malathion killed 100 percent of A. loecki and A. minutus adults within 3 hours of exposure. All insecticides, except azadirachtin, were toxic to A. loecki and A. minutus adults causing over 80 percent of mortality after 24 hours of exposure. Adult mortality by imidacloprid and buprofeziin was higher for A. minutus than for A. loecki. Papaya fruit was left to ripen at room temperature 22 degrees celsius and fruit were checked daily to observed disease development. The postharvest disease incidence varied with season. A greater incidence of anthracnose occurred during cool season while stem end rot was more prevalent in the warm season. Anthracnose usually developed after one week at 22 degrees celsius and stem end rot developed at a slower rate after 10 days. Tissue sample was taken aseptically from diseased fruit and single colony isolated. Collectotrichum was isolated from papaya with anthracnose symptoms. Three other fungi that were isolated are undergoing identification. No direct inhibitory action was observed between the yeast isolates and Collectotrichum growth. This was expected as the yeast is thought to act by denying nutrients for pathogen growth and not a direct inhibitory effect.
Publications
- Thumdee, S., Manenoi, A., and Paull, R.E. 2007. Activity Papaya Fruit Hydrolases During Normal and Modified Ripening, Acta Horticulturae 740: 317-322.
- Manenoi, A., and Paull, R.E. 2007. Effect of 1 Methylcyclopropene (MCP) on Papaya Fruit Ripening, Acta Horticulturae 740:323-326.
- Manenoi, A., Bayogan, E.R.V., Thumdee S., and Paull, R.E. 2007. Utility of 1 Methylcyclopropene as Papaya Postharvest Treatment, Postharvest Biology and Technology 44:55-62.
- Porter, B.W., Zhu, Y.J., and Christopher, D.A. 2009. Carica Papaya Genes Regulated by Phytophthora palmivora: A Model System for Genomic Studies of Compatible Phytophthora Plant Interactions. Tropical Plant Biology 2:84-97.
- Chen, N.J., Manenoi, A., and Paull, R.E. 2007. Papaya Postharvest Physiology and Handling, Problems and Solutions, Acta Horticulturae 740: 285-294.
- Sangwanangkul, P., and Paull, R.E. 2007. The Role of Hexose Transporter in Sugar Accumulation of Papaya Fruit During Maturation and Ripening, Acta Horticulturae 740: 313-316.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Papaya Deregulation Project: Development of transgenic papaya germplasm with broad Papaya Ringspot Virus resistance and longer shelf life to serve the present and future needs of the Hawaiian papaya industry. In 2007, Japan's Ministry of Health Labor and Welfare (MHLW) requested more information on the transgene inserts of SunUp, and had other questions and issues that had to be addressed. These questions required that the southern blots of the transgene inserts be repeated. A comprehensive document was then formulated and completed in December 2007. This new document was submitted to our Japan counterparts for translation into Japanese and subsequently was submitted to the food safety committee of MHLW. In April 2008, we received additional questions from the food safety committee. This required additional laboratory work, these were completed and results submitted to MHLW in August 2008. We are awaiting the results. Project 2 - Pest Status of White Peach Scale in Hawaii and Biological Control Opportunities. The most significant new pest of papaya in Hawaii is the papaya mealybug (Paracoccus marginatus). We have focused on this pest primarily for the reporting period owing to its extreme severity. Papaya mealybug (PMB) was first reported on Maui in 2004, where it caused heavy infestations in papaya and plumeria. PMB is currently found on all main Hawaiian Islands. Since June of 2008 we started a survey of PMB in 5 papaya farms in the Puna area (Big Island) and two papaya farms on Oahu. The aims of the survey are to determine the parasitoids currently associated with PMB as well as their parasitism rates, and to assess the current status of PMB in Hawaii. We also survey botanical gardens such as Maui Nui Botanical Garden and National Tropical Botanical Garden (NTBG). During our surveys in botanical gardens, PMB was found attacking endemic species such Hibiscus brackenridgei, Sida fallax (ilima), Gossypium tomentosum, Pipturus albidus, Gardenia brighamii, Abutilon menziesii, among others, along with papaya. In papaya farms the density of the different stages of PMB varied across months and was significantly higher during summer months. Density of the different stages of PMB also varied across sites. During these surveys we found that A. loecki is the main primary parasitoid associated with PMB in all sites surveyed. No parasitism was observed in second instar PMB, suggesting that this stage might not suitable for parasitism. PARTICIPANTS: Partner organizations include USDA ARS Pacific Basin Agricultural Research Center (PBARC). TARGET AUDIENCES: Papaya growers in Hawaii; Hawaii Papaya Industry Association. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
We believe deregulation of Hawaii's transgenic papayas in Japan is close to approval. This is important because Japan is Hawaii's most important market niche, and to a large extent the Japan market determines the overall economic viability of the Hawaiian papaya industry. A more intangible, but no less important, impact of this work is that papaya will play a significant role in the controversy and debate on the use of transgenic technology in agriculture. Because it was not developed by a large company or by a large industry, the transgenic papayas deflects the concern some anti-GMO activists express about control of food production systems by multi-national companies. Thus, this work has impact beyond the direct benefit to Hawaii's papaya growers. Also important is the fact that papaya is consumed directly and is not blended or mixed in a formulated product. In effect, Japan consumers will provide a second market (besides the US and Canada) for consumers to make a direct choice for or against a transgenic choice, which is clearly labeled (as required by Japan). This data will be vitally important in the determining the public's acceptance or rejection of genetically engineered fruits such as papaya. Since the commercial release of Rainbow and SunUp in 1998, transgenic papaya acreage (mostly Rainbow) has increased every year (except for 1 year when seed availability was limited), from about 38% to just over 70% in 2007. Despite higher prices for non-transgenic Kapoho targeted for sale in Japan, growers have found it increasingly difficult to produce non-transgenic fruit. This large reliance on transgenics, places the industry at risk to the development or introduction of PRSV strains which can overcome the Rainbow resistance, which has led to the development and assessment of segmented- and synthetic coat protein gene transgenic resistance. We have identified several Sunrise lines with segmented gene resistance and have 6 lines with synthetic genes being assessed in the field. After final assessment, and if the resistance continues to be broadly expressed, these newer second generation transgenic papayas will mitigate the risk of new strain formation or introduction of strains from other countries, particularly from Asia. By pyramiding the first and second generation transgene constructs, we hope to develop even more broadly resistant papayas. Thus, this technology could impact papaya production in other areas of the world, besides Hawaii. We have been successful in establishing biological control of papaya mealybug, one of the most devastating pests of papaya if left unchecked, in the major papaya producing areas of Hawaii. Parasitism of PMB by the parasitic wasps ranges from 25% - > 35%, and reduces pest density within three months of release into a particular area. The impact that these parasitoids have results in reduced dependence on insecticides by the growers.
Publications
- Ming, R., Hou, S., Feng, Y., Yu, Q., Dionne-Laporte, A., Saw, J. H., Senin, P., Wang, W., Ly, B. Y., Lewis, K. L. T., Salzberg, S. L., Feng, L., Jones, M. r., Skelton, R. L., Murray, J. E., Chen, C., Qian, W., Shen, J., Du, P., Eustice, M., Tong, E., Tang, H., Lyons, E., Paull, R. E., Michael, T. P., Wall, K., Rice, D., Albert, H., Wang, M.-L., Zhu, Y. J., Schatz, M., Nagarajan, N., Agbayani, R., Guan, P., Blas, A., Wai, C. M., Ackerman, C. M., Ren, Y., Liu, C., Wang, J., Wang, J., Na, J.-K., Shakirov, E. V., Haas, B., Thimmanpuram, J., Nelson, D., Wang, X., Bowers, J. E., Gschwend, A. R., Delcher, A. L., Singh, R., Suzuki, J. Y., Tripathi, S., Neupane, K., Wei, H., Irikura, B., Paidi, M., Jiang, N., Zhang, W., Presting, G., Windsor, A., Navajas-Perez, R., Torres, M. J., Feltus, F. A., Porter, B., Li, Y., Burroughs, A. M., Luo, M.-C., Liu, L., Christopher, D. A., Mount, S. M., Moore, P. H., Sugimura, T., Jiang, J., Schuler, M. A., Fiedman, V., Mitchell-Olds, T., Shippen, D. E., dePamphilis, C., Palmer, J. D., Freeling, M., Paterson, A. H., Gonsalves, D., Wang, L. & Alam, M. (2008). A draft genome of the transgenic tropical fruit tree papaya (Carica papaya Linnaeus). Nature 452, 991-996.
- Gonsalves, D., Suzuki, J., Tripathi, S. & Ferreira, S. (2008). Papaya ringspot virus (Potyviridae). In Encyclopedia of Virology, 5 vols, 3rd Edition, pp. vol. 4, pp. 1-8. Edited by B. Mahy & M. Van Regenmortel. Oxford: Elsevier.
- Gonsalves, D., Ferreira, S., Suzuki, J. & Tripathi, S. (2008). Papaya. In A Compendium of Transgenic Crop Plants: Tropical and Subtropical Fruits and Nuts, pp. 131-162. Edited by C. Kole & T. C. Hall. Oxford, UK: Blackwell Publishing Ltd.
- Tripathi, S., Suzuki, J., Ferreira, S. & Gonsalves, D. (2008). Papaya Ringspot Virus: Characteristics, Pathogenicity, Sequence Variability and Control. Molecular Plant Pathology 9, 269-380.
- Robert E. Paull, Beth Irikura, Ping Fang Wu, Helen Turano, Nancy Jung Chen, Andrea Blas John K. Fellman, Andrea R. Gschwend, Ching Man Wai, Qingyi Yu, Gernot Presting, Maqsudul Alam, Ray Ming, 2008. Fruit Development, Ripening and Quality Related Genes in the Papaya Genome. Tropical Plant Biology. In Press
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: Papaya cell wall modification is involved in softening during ripening. Line 8 and Sunset fruit lost greater than one-half of the cell wall mass during ripening. This significant reduction of mesocarp cell wall mass occurred in the CDTA-soluble fractions, Na2CO3-soluble fractions, and the cellulose fraction. Beside uronic acids, galactosyl and xylosyl components of mesocarp cell wall showed significant decline from the mesocarp cell wall. The modifications of cell wall polysaccharides containing xylosyl and galactose seemed to play a significant role in normal softening of both papaya lines. Treatment with 1-MCP altered the papaya softening pattern and caused incomplete softening. The 1-MCP-treated papaya showed that although the major changes occurred in galactosyl components of the mesocarp cell wall comparable to that in untreated control papaya; the 1-MCP-treated papaya did not soften completely. The changes in the 1-MCP-trearted papaya suggested that modification of the
xylosyl containing components of the cell wall was involved in papaya mesocarp softening. The changes in the fractions containing xylosyl residue in 1-MCP treatment included less solubilization of xylosyl residues, and a higher association of xylosyl residues to pectic polysaccharides of the middle lamella and to loosely bound matrix polysaccharides. To create a super Rainbow, Papaya Ringspot Virus (PRSV-resistant transgenic papaya with broader resistance to foreign PRSV strains, Kapoho lines with segmented transgenes previously selected and targeted for deregulation were crossed with SunUp to produce the Rainbow equivalent F1 hybrid, thus pyramiding the original PRSV coat protein transgene in Rainbow with the newer segmented PRSV transgenes. In effect, this increases the transgene dose and should broaden the transgenic resistance to foreign PRSV strains. Crosses were made between SunUp and selected transgenic lines, including KKTV-118kp and KKTV-111kp which we are targeting for
deregulation.
PARTICIPANTS: Partner organizations include USDA ARS Pacific Basin Agricultural Research Center (PBARC).
TARGET AUDIENCES: papaya growers in Hawaii; Hawaii Papaya Industry Association.
Impacts
Hydrolases activity, except for PG, was correlated with normal softening. When softening was modified by 1-MCP treatment, the papaya showed a delayed rises in some hydrolases' activities. However, only endoxylanase activity was completely suppressed throughout ripening of 1-MCP-treated papaya. The failure of 1-MCP-treated papaya to soften completely was possibly associated with a selective suppression of endoxylanase activity. Papaya softening, like other fruit, is a complex event that involves many cell wall hydrolases, such as endoxylanase, xylosidase, b-galactosidase and endoglucanase. These hydrolases may play their roles in concert, to provide the unique texture of a particular fruit. Papaya Ringspot Virus is not just a single virus but rather many viruses each with unique genetic signatures. The original transgenic Rainbow papaya contained coat proteins from a single PRSV. This virus, at the time, was the predominant threat. It has since been discovered that
there are many other strains of the virus found elsewhere in the world. Segmented genes from these different strains have been isolated and by placing these genes into new transgenic papaya, resistance to these other virus strains can be conveyed. Not only does this protect Hawaiian papaya growers but also producers elsewhere in the world.
Publications
- Chen, N. J., A. Manenoi, R. E. Paull. 2007. Papaya postharvest physiology and handling - problems and solutions. Acta Horticulturae 740:285-294.
- Sangwanangkul, P., R. E. Paull. 2007. The role of hexose transporter in sugar accumulation of papaya fruit during maturation and ripening. Acta Horticulturae 740:313-316.
- Thumdee, S., A. Manenoi, R. E. Paull. 2007. Activity of papaya fruit hydrolases during normal and modified ripening. Acta Horticulturae 740:317-322.
- Manenoi, A. R. E. Paull. 2007. Effect of 1-methylcyclopropene (MCP) on papaya fruit ripening. Acta Horticulturae 740:323-326.
- Manenoi, A., E. R. V.Bayogan, S. Thumdee and R. E. Paull. 2007. Utility of 1-Methylcyclopropene as a Papaya Postharvest Treatment. Postharvest Biology and Technology 44:55-62.
- Gonsalves, D. (2006). Transgenic Papaya: Development, Release, Impact, and Challenges. Advances in Virus Research 67, 317-354.
- Gonsalves, D., Vegas, A., Prasartsee, V., Drew, R., Suzuki, J. and Tripathi, S. (2006). Developing Papaya to Control Papaya Ringspot Virus by Transgenic Resistance, Intergeneric Hybridization, and Tolerance Breeding. Plant Breeding Reviews 26, 35-78.
- Tripathi, S., Suzuki, J. and Gonsalves, D. (2006). Development of Genetically Engineered Resistant Papaya for Papaya ringspot virus in a Timely Manner- A Comprehensive and Successful Approach. In Plant-Pathogen Interactions: Methods and Protocols, pp. 197-239. Edited by P. Ronald. Totowa, New Jersey: The Humana Press, Inc.
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Progress 10/01/05 to 09/30/06
Outputs
I. Comparison of Yield and Quality of Papaya ringspot virus (PRSV) Resistant, Micropropagated Papaya Selections in Different Environments. Three monthly harvests were conducted in two of three replicated field trials of 11 Laie Gold lines established in 2005 with cooperating growers in Kahuku, Kahaluu, and Laie. The Kahaluu test was completely destroyed as a result of the continuous rainy weather in February to March 2006. The Kahuku field was located next to a dry stream bed that was filled with water during the rainy season. More than 50% of the trees from Kahuku succumbed to root rot. Although harvest data were obtained, the fruits were noticeably smaller than the Laie fruit. Few of the trees in Laie were lost. Harvests in the Laie field were analyzed for average fruit size. Growers in that area prefer larger 800-900 g fruit. One of the clones, LG8-19, consistently produced among the largest average fruit weights in each of the three harvests (865 g, 877 g, and 838
g). Other lines had average weights that fluctuated from high (>850 g) to low (700 g) or vice versa. Therefore, micropropagation of LG8-19 could result in the most consistent large fruited crop in the Laie area. II. Pest status of white peach scale (Pseudaulacaspis pentagona, Hemiptera: Diaspididae) in Hawai'i and biological control opportunities on Papaya. Field surveys revealed substantial infestation levels in all Kapoho plots throughout the term of this project. The percentage of trees with established WPS females was very high in the F1 and F2 plots, and the high levels of male activity recorded also indicates that the females present were mature and actively recruiting males with pheromones. Roughly 20 % of the trees had young scales or 'crawlers' during the sampling periods, and the identity of the trees that were reproductively active changed from sampling period to sampling period. The older field, F2, had a lower reproductive output of crawlers even though its female
infestation level was the highest.
Impacts
Papayas are usually multiple-planted as seedlings and thinned at flowering time to a single hermaphrodite tree. By using a single planting of clonally propagated trees, developed through micropropagation, produce fruit lower on the trunk, earlier and in greater abundance than thinned seedlings. Use of micropropagated clonally propagated trees can prevent losses due to poor fruit production or deformed fruit. Clonally propagated hermphrodite papayas selected for high production and quality could provide increased revenues for growers with no additional inputs after the higher initial plant purchase. Re-infestation of the papaya trunk after physical removal of the scales was relatively slow (only about 5% of the original scale load was regained after 5 months of observation) but the potential for growth of WPS can not be underestimated. Sampled plots with low level infestation suffered a doubling in scale density in only 4 to 5 months, in spite of the seemingly moderate
re-infestation levels recorded. Data show that re-infestation is more likely, and happens more quickly, in plots with higher established populations of WPS. We recorded the presence of two species of predatory beetles Rhyzobius spp. (Chrysomelidae) and Cybocephalus nipponicus (Nitidulidae), these natural enemies appeared to selectively visit high density areas of WPS, but their numbers were relatively low and they appear to have limited impact on the overall population levels of the WPS.
Publications
- Fitch, MMM, Moore PH, Leong TCW, Akashi LAY, Yeh ACF, White SA., Dela Cruz AS, Santo LT, Ferreira SA, and Poland LJ. 2005. Clonally propagated and seed-derived papaya orchards: 1. Plant production and field growth. HortScience 40(5): 1283-1290.
- Fitch, MMM, Moore PH, Leong TCW, Akashi LAY, Yeh ACF, White SA., Dela Cruz AS, Santo LT, Ferreira SA, and Poland LJ. 2005. Clonally propagated and seed derived papaya orchards: 2. Yield comparison. HortScience 40(5): 1291-1297.
- Fitch, MMM. 2004. Papaya. Biotechnology of Fruit and Nut Crops, Ed. Richard E. Litz, CAB International, Wallingford, pp. 174-207.
- Fitch, M., Leong, T., Saito, N., Yamamoto, G., Dela Cruz, G., Yeh, A., White, S., Maeda, S., Moore, P. (2004) Photoautotrophic medium and PPMTM help to alleviate losses from bacterial contamination in papaya micropropagation. In Vitro Cell Dev Biol 40:32-A
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