Progress 09/01/06 to 08/31/09
Outputs
OUTPUTS: Papaya from the trees of the Slow ripening Line 4-16 were harvested every two weeks. Fruit stored at 10oC became more susceptible to postharvest disease than non-stored fruit as the length of storage time increased. Fungi decay was not immediately noticed upon removal from storage in fruit stored only for 2 weeks, decay developed subsequently during ripening at ambient temperature. Longer storage (3 and 4 weeks), allowed the decay to develop during cold storage. The decay rate was recorded two days after fruit were removed to ambient temperature and increased dramatically from 12% to near 40% when storage period increased from 2 to 4 weeks. The decay rate was not significantly different due to the high standard variation. The susceptibility to decay varied greatly from season to season. Papaya fruit lost average 0.75 to 0.85% of fresh weight per day when ripen at ambient temperature. During cold storage, the weight loss was limited to less than 2% regardless the length of the storage. The weight loss increased to 1.2% to 1.45% per day when fruit were removed from cold storage to ambient temperature. Fruit stored at 10oC colored faster (7 to 8 days) when removed from 10oC and ripen at ambient temperature, than those without cold storage (8 to 10 days). This faster degreening and softening in flesh of cold stored fruit than non-stored fruit has been previously observed in Sunset papaya. The SSR markers for hard and soft papaya fruit was completed. A total of 556 primers sets were screened against hard and soft papaya parents, and 124 of these were found to show polymorphisms. Of these, 44 primers were selected at about 10 cM intervals throughout the 12 linkage groups. Two papaya parents producing hard fruit and two papaya parents producing soft fruit were chosen and compared to 176 F2 papaya plants chosen to represent the full range of fruit firmness phenotypic data as obtained from the field trial. To date, 65 primer sets have been completed on these 180 individuals. One potential QTL (~500kbp) has been isolated that has fifty predicted genes. The papaya BAC clones available for this QTL region is incomplete. Eleven of the predicted genes in the QTL show little or no expression at the mature green or the 35% yellow stage of ripening. Seven genes were up-regulated more than two-fold, twenty-five genes down-regulated and the rest showed less than two-fold change between stages. The seven up-regulated genes included two unknowns. Two other genes with homology to TGF beta-Receptor interacting proteins are down-regulated along with a RNA binding protein, a phosphatase and two unknowns. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The first outcome is the availability of naturally slow-ripening papaya lines that will enhance production and expand the marketing area. A second outcome is the acquisition of unique genetic markers for the slow-softening trait. Identified markers is the first essential steps in a forward genetic approach to the isolation of the gene(s) involved in this unique character. If this character is controlled by a single gene, then it could become the basis for research on the control of fruit ripening. Our natural slow ripening papaya Psls takes twice as long to soften to the edible ripe stage as commercial lines. An understanding of the molecular basis for this delay would have application to other fleshy fruit crops and would be useful in extending the outcomes of this proposal. An extension of fruit postharvest life would reduce losses in a systemic way and facilitate market expansion. Fruit that soften more slowly during ripening also allow greater flexibility in harvest scheduling. Packers/shippers could grade such fruit more accurately on the basis of skin color. Wholesalers and retailers would receive uniformly colored fruit with a longer retail shelf life, and consumers would receive a higher quality product.
Publications
- 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 1, 246-277
- Thumdee, Siwaporn, Ashariya Manenoi, Nancy J. Chen, Robert E. Paull. 2010. Papaya Fruit Softening: Role of Hydrolases. Tropical Plant Biology 3, 98-109.
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Progress 09/01/07 to 08/31/08
Outputs
OUTPUTS: Papaya from the trees of the Slow ripening Line 4-16 were harvested every two weeks. Fruit stored at 10oC became more susceptible to postharvest disease than non-stored fruit as the length of storage time increased. Fungi decay was not immediately noticed upon removal from storage in fruit stored only for 2 weeks, decay developed subsequently during ripening at ambient temperature. Longer storage (3 and 4 weeks), allowed the decay to develop during cold storage. The decay rate was recorded two days after fruit were removed to ambient temperature and increased dramatically from 12% to near 40% when storage period increased from 2 to 4 weeks. The decay rate was not significantly different due to the high standard variation. The susceptibility to decay varied greatly from season to season. Papaya fruit lost average 0.75 to 0.85% of fresh weight per day when ripen at ambient temperature. During cold storage, the weight loss was limited to less than 2% regardless the length of the storage. The weight loss increased to 1.2% to 1.45% per day when fruit were removed from cold storage to ambient temperature. Fruit stored at 10oC colored faster (7 to 8 days) when removed from 10oC and ripen at ambient temperature, than those without cold storage (8 to 10 days). This faster degreening and softening in flesh of cold stored fruit than non-stored fruit has been previously observed in Sunset papaya. Abnormal softening caused by chilling injury was observed in papaya stored for more than 3 weeks at 10oC. Chilling injury symptoms developed in fruit only after removal from cold storage and left to ripen at ambient temperature. The chilling injury symptoms were less obvious in fruit harvested during the warm season. Papaya harvested in spring showed a high rate of chilling symptom. The higher field temperature could have a preconditioning effect to prevent chilling injury. The SSR markers for hard and soft papaya fruit are completed. A total of 556 primers sets have been screened against hard and soft papaya parents, and 124 of these were found to show polymorphisms. Of these, 44 primers were selected at about 10 cM intervals throughout the 12 linkage groups. Two papaya parents producing hard fruit and two papaya parents producing soft fruit were chosen and compared to 176 F2 papaya plants chosen to represent the full range of fruit firmness phenotypic data as obtained from the field trial. To date, 65 primer sets have been completed on these 180 individuals. One potential QTL has been isolated. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The first outcome is the availability of naturally slow-ripening papaya lines that will enhance production and expand the marketing area. A second outcome is the acquisition of unique genetic markers for the slow-softening trait. Identified markers are the first essential steps in a forward genetic approach to the isolation of the gene(s) involved in this unique character. If this character is controlled by a single gene, then it could become the basis for research on the control of fruit ripening. This has potential applications to other fruit.
Publications
- R. Ming, S. Hou, Y. Feng, Q. Yu, A. Dionne-Laporte J.H. Saw, P. Senin, W. Wang, B. V. Ly, K.L.T. Lewis, S.L. Salzberg, L. Feng, M.R. Jones, R.L. Skelton, J.E. Murray, C. Chen, W. Qian, J. Shen, P. Du, M. Eustice, E. Tong, H. Tang, E. Lyons, R.E. Paull, T.P. Michael, K. Wall, D. Rice, H. Albert, M.Li Wang, Y.J. Zhu, M. Schatz, N. Nagarajan, R. Agbayani, P. Guan, A. Blas, C.Man Wai, C.M. Ackerman, Y. Ren, C. Liu, J. Wang, J. Wang, J.K. Na, E.V Shakirov, B. Haas, J. Thimmapuram, D. Nelson, X. Wang, J.E. Bowers, A. R. Gschwend, A.L. Delcher, R. Singh, J.Y. Suzuki, S. Tripathi, K. Neupane, H. Wei, B. Irikura, M. Paidi, N. Jiang, W. Zhang, G. Presting, A. Windsor, R. Navajas-Perez, M. J. Torres. F. A. Feltus, B. Porter, Y. Li, A.M. Burroughs, M.C. Luo, L. Liu, D.A. Christopher, S.M. Mount, P.H. Moore, T. Sugimura, J. Jiang, M.A. Schuler, V. Friedman, T. Mitchell-Olds, D.E. Shippen, C.W. dePamphilis, J.D. Palmer, M. Freeling, A. H. Paterson, D. Gonsalves, L. Wang, M. Alam. 2008. Genome of the transgenic tropical fruit tree papaya (Carica papaya Linnaeus). Nature 452: 991-996.
- Cuixia Chen, Qingyi Yu, Shaobin Hou, Yingjun Li, Moriah Eustice, Rachel L. Skelton, Olivia Veatch, Rachel E. Herdes, Lauren Diebold, Jimmy Saw, Yun Feng, Wubin Qian, Lee Bynum, Lei Wang, Paul H. Moore, Robert E. Paull, Maqsudul Alam, Ray Ming. 2007 Construction of a Sequence-Tagged High Density Genetic Map of Papaya for Comparative Structural and Evolutionary Genomics in Brassicales. Genetics 177: 2481-2491
- Manenoi, A., R. E. Paull. 2007. Papaya fruit softening, endoxylanase gene expression, protein and activity. Physiologia Plantarum 131:470-480
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Progress 09/01/06 to 08/31/07
Outputs
Papaya from the trees remaining in our commercial planting of the Slow ripening Line 4-16 were harvested every two weeks. Fruit stored at 10oC became more susceptible to postharvest disease than non-stored fruit as the length of storage time increased. Fungi decay was not immediately noticed upon removal from storage in fruit stored only for 2 weeks, decay developed subsequently during ripening at ambient temperature. Longer storage (3 and 4 weeks), allowed the decay to develop during cold storage. The decay rate was recorded two days after fruit were removed to ambient temperature and increased dramatically from 12% to near 40% when storage period increased from 2 to 4 weeks. The decay rate was not significantly different due to the high standard variation. The susceptibility to decay varied greatly from season to season. Papaya fruit lost average 0.75 to 0.85% of fresh weight per day when ripen at ambient temperature. During cold storage, the weight loss was limited
to less than 2% regardless the length of the storage. The weight loss increased to 1.2% to 1.45% per day when fruit were removed from cold storage to ambient temperature. Fruit stored at 10oC colored faster (7 to 8 days) when removed from 10oC and ripen at ambient temperature, than those without cold storage (8 to 10 days). This faster degreening and softening in flesh of cold stored fruit than non-stored fruit has been previously observed in Sunset papaya. Abnormal softening caused by chilling injury was observed in papaya stored for more than 3 weeks at 10oC. Chilling injury symptoms developed in fruit only after removal from cold storage and left to ripen at ambient temperature. The chilling injury symptoms were less obvious in fruit harvested during the warm season. Papaya harvested in spring showed a high rate of chilling symptom. The higher field temperature could have a preconditioning effect to prevent chilling injury. More fruit are needed to study the respiration, ethylene
evolution and deformation changes following cold storage. The old field is not producing enough healthy fruit for that part of the study due to the loss of 70% of the trees in 2006 after forty days of rain. We are waiting for fruit from a new field that has just started to set fruit. The effort to map the SSR markers for hard and soft papaya fruit is nearing completion. A total of 556 primers sets have been screened against hard and soft papaya parents, and 124 of these were found to show polymorphisms. Of these, 44 primers were selected at about 10 cM intervals throughout the 12 linkage groups. Two papaya parents producing hard fruit and two papaya parents producing soft fruit were chosen and compared to 176 F2 papaya plants chosen to represent the full range of fruit firmness phenotypic data as obtained from the field trial. To date, 39 primer sets have been completed on these 180 individuals. It is expected that all 44 primers will be done by the end of September. A spreadsheet
containing all the summarized data is being developed and will be completed by the end of September.
Impacts
The first outcome is the availability of naturally slow-ripening papaya lines that will enhance production and expand the marketing area. A second outcome is the acquisition of unique genetic markers for the slow-softening trait. Identifying these markers would be the first essential steps in a forward genetic approach to the isolation of the gene(s) involved in this unique character. If this character is controlled by a single gene, then it could become the basis for research on the control of fruit ripening. This has potential applications to other fruit.
Publications
- Chen, N. J., A. Manenoi, R. E. Paull. 2007. Papaya postharvest physiology and handling - problems and solutions. Acta Horticulturae 740:285-294.
- Thumdee, S., A. Manenoi, R. E. Paull. 2007. Activity of papaya fruit hydrolases during normal and modified ripening. Acta Horticulturae 740:317-322.
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