Skip to main content
ARS Home » Research » Publications at this Location » Publication #207679
Title: Physical Mapping Of A Sex Reversal Mutation On Papaya Y Chromosome

Author
item YU, QINGYI - HI AG RESEARCH CENTER
item Moore, Paul
item SKELTON, RACHEL - HI AG RESEARCH CENTER
item BLAS, ANDREA - UNIVERSITY OF HAWAII
item MING, RAY - UNIV OF ILL AT URBANA

Submitted to: Plant and Animal Genome Conference
Publication Type: Proceedings
Publication Acceptance Date: 10/3/2006
Publication Date: 1/24/2007
Citation: Yu, Q., Moore, P.H., Skelton, R.L., Blas, A., Ming, R. 2007. Physical Mapping Of A Sex Reversal Mutation On Papaya Y Chromosome. Plant and Animal Genome Conference XV.

Interpretive Summary: not applicable

Technical Abstract: Unlike animal species, most flowering plants are hermaphrodite, producing flowers that contain both male and female organs. Papaya is one of the limited number of plant species that produce male, female, and hermaphrodite flowers on separate individuals, offering us the opportunity of investigating sex determination in plants. Sex determination in papaya is controlled by a primitive Y chromosome containing functional or degenerated genes regulating stamen and carpel development and embryo abortion. Sequencing the male-specific region of the Y chromosome (MSY) and its corresponding region on the X chromosome in papaya is underway and will provide sequence information necessary for cloning the sex determination genes in papaya. We used Co60 ã-irradiation to treat pollens of gynodioecious variety SunUp and dioecious variety AU9 to produce Y deletion lines. The irradiation dosages used were 3, 5, and 10 krad. Three mutant plants were found among about 5000 plants derived from treated pollens and all three mutants were from 5 krad treatment that appeared to be the optimal dosage for generating deletion lines in papaya. All three mutants were from treated AU9 pollens and had long peduncle – a trait typically linked to male plants. One of the mutants exhibited typical female flowers while the other two mutants showed hermaphrodite flowers. A total of 392 pairs of primers covering about 580kb sequenced region were designed from five completely sequenced MSY BACs and used for amplification of the genomic DNA from mutant plants. The PCR products were sequenced and the results confirmed that all three mutants had the male Y chromosome sequences except few single nucleotide changes. Physical mapping of the sex reversal mutants revealed a large deletion containing the 128kb MSY BAC 99O03 in the mutant reversed from male to female. Functional analysis of this deleted region might reveal candidate genes for sex-determination in papaya.