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Title: HIGH-DENSITY LINKAGE MAPPING REVEALED SUPPRESSION OF RECOMBINATION AT THE SEX DETERMINATION LOCUS IN PAPAYA.

Author
item MA, H - HI AG RES CNT
item Moore, Paul
item LIU, Z - HI AG RES CNT
item KIM, M - HI AG RES CNT
item YU, Q - HI AG RES CNT
item Fitch, Maureen
item SEKIOKA, T - UNIV OF HAWAII
item PATERSON, A - UNIV OF GEORGIA
item MING, R - HI AG RES CNT

Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2003
Publication Date: 12/15/2003
Citation: Ma, H., Moore, P.H., Liu, Z., Kim, M.S., Yu, Q., Fitch, M.M., Sekioka, T., Paterson, A.H., Ming, R. 2003. High-density linkage mapping revealed suppression of recombination at the sex determination locus in papaya. Genetics 166: 419-436. 2004.

Interpretive Summary: Few details are known about how sex chromosomes are involved in plant sex determination even though proper expression of plant sex is THE single most important contributor to yield of all fruit and seed producing crops. Collaborative research in Hawaii among the Tropical Plant Physiology Production and Disease Unit of the Pacific Basin Agricultural Research Center, the Hawaii Agriculture Research Center, the University of Hawaii, and the University of Georgia produced a high density DNA linkage map of papaya. The papaya linkage map revealed a severe suppression of genetic recombination at the sex determination locus with 15% of the 1500 markers cosegregating with sex types. This high-density genetic map will be essential for cloning specific genes of interest including the sex determination gene and may reveal genes and their regulatory elements that can be managed to attain proper sex expression for high yield stability in seed and fruit crops.

Technical Abstract: A high-density genetic map of papaya (Carica papaya L.) was constructed using 54 F2 plants derived from cultivars Kapoho and SunUp with 1501 markers, including 1498 amplified fragment length polymorphism(AFLP) markers, the papaya ringspot virus coat protein marker, morphological sex type, and fruit flesh color. These markers were mapped into 12 linkage groups at a LOD score of 5.0 and recombination frequency of 0.25. The 12 major linkage groups covered a total length of 3294.2 cM, with an average distance of 2.2 cM between adjacent markers. This map revealed severe suppression of recombination around the sex determination locus with a total of 225 markers cosegregating with sex types. The cytosine bases were highly methylated in this region on the basis of the distribution of methylation-sensitive and-insensitive markers. This high-density genetic map is essential for cloning of specific genes of interest such as the sex determination gene and for the integration of genetic and physical maps of papaya.