Plant Molecular Biologist

 

 

Education

Current Research

Flower Development and Sex Chromosome Evolution in Papaya: Unlike most animal species that produce unisexual individuals, the majority of flowering plants produce flowers that are ‘perfect’ and contain both ‘male’ and ‘female’ organs. Less than 10% of plant species produce flowers, which are unisexual. Papaya is a polygamous plant species producing both dioecious and perfect flowers and provides an opportunity for studying flower development in dioecious and hermaphrodite plant species.

The sex determination system in papaya is particularly intriguing, not only because it has three sex types within the species, also because it shows frequent sex reversal caused by environmental factors. Recent studies showed that sex determination in papaya is controlled by a pair of primitive sex chromosomes. We are working on physical mapping and sequencing the male specific Y chromosome (MSY) and its corresponding region on X chromosome as the first step towards cloning the sex determination genes in papaya.

Papaya Genomics: Papaya is diploid species with 9 pairs of chromosomes. Its genome size is 372 Mb, which is smaller than most of other plant genomes. The generation time of papaya is as short as 9 month. Because papaya is a polygamous species, hand-pollination is easily done. From each hand-pollinated fruit, it produces 800 to 1,000 seeds. Vegetative propagation is possible by cuttings or by tissue culture. A genetic transformation system is well established. The above favorable properties make papaya an excellent model system of fruit trees for genomic studies.

The draft sequence with 3X coverage of papaya genome has been finished by the Hawaii Papaya Genome Consortium. A high-density genetic map with 706 sequence-based SSR markers and a FPC-based physical map have been constructed. With these genetic and genomic resources available, we are mapping quantitative trait loci controlling agronomically important traits (such as fruit size and fruit weight) and cloning genes related to nutritional profile (such as flesh color) for papaya improvement.

Recent Publications

Yu, Q., D. Steiger, E.M. Kramer, P.H. Moore, R. Ming. 2008. Floral MADS-box genes in trioecious papaya: Characterization of AG and AP1 subfamily genes revealed a sex-type-specific gene. 2008. Tropical Plant Biology (Accepted)

Yu, Q., S. Hou, F.A. Feltus, M.R. Jones, J.E. Murray, O. Veatch, C. Lemke, J. H. Saw, R.C. Moore, J. Thimmapuram, L. Liu, P.H. Moore, M. Alam, J. Jiang, A.H. Paterson, R. Ming. 2008. Low X/Y divergence in four pairs of papaya sex linked genes. Plant J. DOI: 10.1111/j.1365-313X.2007.03329.x

Ackerman, C.M. *, Q. Yu*, S. Kim, R.E. Paull, P.H. Moore, R. Ming. 2008. Differential expression of B-class MADS-box genes in trioecious papaya flowers. Planta DOI: 0.1007/s00425-007-0653-5 (* Authors contributed equally to this work.).

Eustice, M., Q. Yu, W. C. Lai, S. Hou, J. Thimmapuram, L. Liu, M. Alam, P.H. Moore, G.G. Presting, R. Ming. 2008. Development and application of microsatellite markers for genomic analysis of papaya. Tree Genetics and Genomes DOI: 10.1007/s11295-007-0112-2

Chen, C., Q. Yu, S. Hou, Y. Li, M. Eustice, R.L. Skelton, O. Veatch, R. Herds, L. Diebold, J. Saw, Y. Feng, L. Bynum, L. Wang, P.H. Moore, R.E. Paull, M. Alam, R. Ming. 2007. Construction of a high density genetic map of papaya using microsatellites derived from BAC end and whole genome shotgun sequences for comparative structural and evolutionary genomics in Brassicales. Genetics DOI: 10.1534/genetics.107.081463

Ming, R., Q. Yu, P.H. Moore. 2007. Sex determination in papaya. Seminars in cell and developmental biology 18:401-408.

Yu, Q., S. Hou, R. Hobza, F.A. Feltus, X. Wang, W. Jin, R.L. Skelton, A. Blas, C. Lemke, J. H. Saw, P.H. Moore, M. Alam, J. Jiang, A.H. Paterson, B. Vyskot, R. Ming. 2007. Chromosomal location and gene paucity of the male specific region on papaya Y chromosome. Molecular Genetics and Genomics 278 (2):177-185.

Lai, C.W.J.*, Q. Yu*, S. Hou, R.L. Skelton, M.R. Jones, K.L.T. Lewis, J. Murray, M. Eustice, P. Guan, R. Agbayani, P.H. Moore, R. Ming, G.G. Presting. 2006. Analysis of papaya BAC end sequences reveals first insights into the organization of a fruit tree genome. Molecular Genetics and Genomics 276(1): 1-12 (* Authors contributed equally to this work.).

Skelton, R. L., Q. Yu, R. Srinivasan, R. Manshardt, P. H. Moore, R. Ming. 2006. The expression of the gene for Lycopene ß-cyclase is elevated in leaves and flowers and down-regulated in both yellow- and red- fleshed papaya fruits. Cell Research 16 (8): 731-739.

Yu, Q., P. H. Moore, H. H. Albert, A. H.K. Roader, R. Ming 2005 Cloning and characterization of a FLORICAULA/LEAFY ortholog, PFL, in polygamous papaya. Cell Research. 15(8): 576-584.

Alvarez, A.M., K.J. Trotter, M.B. Swafford, J.M. Berestecky, Q. Yu, R. Ming, P.R. Hepperly, and F. Zee, 2005. Characterization and detection of Ralstonia solanacearum strains causing bacterial wilt of ginger in Hawaii. pp 471-477 in: Bacterial Wilt Disease and the Ralstonia solanacearum species complex. C. Allen, P. Prior, and A.C. Hayward, eds. APS Press (American Phytopathological Society) St.Paul, Mn.

Ma, H., P. H. Moore, Z. Liu, M. S. Kim, Q. Yu, M. M. M. Fitch, T. Sekioka, A. H. Paterson, R. Ming 2004 High-density genetic mapping revealed suppression of recombination at the sex determination locus in papaya. Genetics 166:419-436.

Liu, Z., P. H. Moore, H. Ma, C. M. Ackerman, R. Makandar, Q. Yu, H. M. Pearl, M. S. Kim, J. W. Charlton, J. I. Stiles, F. T. Zee, A. H. Paterson, R. Ming 2004 A primitive Y chromosome in papaya marks incipient sex chromosome evolution. Nature 427:348-352.

Schenck, S., M.W. Crepeau, K.K. Wu, P.H. Moore, Q. Yu, R. Ming. 2004 Genetic Diversity and Relationships in Native Hawaiian Saccharum officinarum Sugarcane. Journal of Heredity 95: 327-331.

Yu, Q., A.M. Alvarez, P.H. Moore, F. Zee, M.S. Kim, A. de Silva, P.R. Hepperly, R.Ming. 2003 Molecular Diversity of Ralstonia solanacearum Isolated from Ginger in Hawaii. Phytopathology 93: 1124-1130.