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Title: PAPAYA GENOMICS

Author
item MING, RAY - HI AG RES CNT
item Osterman, Greg
item LIU, ZHIYONG - HI AG RES CNT
item MA, HAO - HI AG RES CNT
item YU, QINGYI - HI AG RES CNT
item KIM, MINNA - HI AG RES CNT
item Fitch, Maureen
item SEKIOKA, TERRY - UNIV OF HAWAII

Submitted to: Plant Biology
Publication Type: Abstract Only
Publication Acceptance Date: 2/20/2003
Publication Date: 7/25/2003
Citation: Ming, R., Osterman, G.J., Liu, Z., Ma, H., Yu, Q., Kim, M.S., Fitch, M.M., Sekioka, T. 2003. Papaya genomics. Plant Biology 2003: P999, pg 203. 2003.

Interpretive Summary: Abstract only.

Technical Abstract: Because of its relatively small genome (372Mb/1C) and ability to produce ripe fruit 9 to 12 months after planting, papaya (Carica papaya L.) can be a model for studying genes that affect fruit characters. We are developing papaya genomics to understand germplasm diversity, construct a high density genetic map, map quantitative trait loci (QTL) controlling agronomic traits, and clone major genes. Genetic relationships among papaya cultivars, breeding lines, unimproved germplasm, and related species were established using amplified fragment length polymorphism (AFLP) markers. Seventy-one papaya accessions and related species were analyzed. Only limited genetic diversity was detected among cultivated and wild papaya germplasm. Our results indicate that self-pollinated hermaphrodite cultivars are as variable as open-pollinated dioecious cultivars. AFLP markers were also used to construct a papaya genetic map based on 54 F2 plants derived from the cultivars Kapoho and SunUp. A total of 1771 AFLP markers were generated from 781 EcoR I/Mse I and Pst I/Mse I primer sets. Our high-resolution genetic map revealed 225 AFLP markers co-segregating with sex. This large number of co-segregating markers suggests severe suppression of recombination in the genomic region containing the sex locus. We used this high-density map as a scaffold for mapping QTLs contributing to agronomic and developmental traits. We also constructed a bacterial artificial chromosome (BAC) library from high molecular weight DNA to provide an additional molecular tool. This BAC library consists of 39,168 clones with average insert size of 132kb providing 13.7x papaya genome equivalents. This BAC library has been used for cloning the sex determination gene and selected meristem and floral organ identity genes.