Chromosomal location and gene paucity of the male specific region on papaya Y chromosome

• Published in: Molecular genetics and genomics : MGG 2007-08, Vol.278 (2), p.177-185
• Main Authors: Yu, Qingyi, Hou, Shaobin, Hobza, Roman, Feltus, F. Alex, Wang, Xiue, Jin, Weiwei, Skelton, Rachel L, Blas, Andrea, Lemke, Cornelia, Saw, Jimmy H, Moore, Paul H, Alam, Maqsudul, Jiang, Jiming, Paterson, Andrew H, Vyskot, Boris, Ming, Ray
• Format: Article
• Language: English
• Subjects: Artificial chromosomes; Bacterial artificial chromosomes; Carica - genetics; Carica papaya; centromeres; Chromosome Mapping; Chromosomes, Artificial, Bacterial; Chromosomes, Plant - genetics; Flowering; Fluorescence in situ hybridization; Gene mapping; Genes; Genes, Plant - genetics; Genetics; Genomics; Hermaphrodites; Hybridization; In Situ Hybridization, Fluorescence; Magnoliophyta; male specific region; molecular sequence data; Nucleotide sequence; nucleotide sequences; papayas; Recombination; repetitive sequences; Repetitive Sequences, Nucleic Acid; Sex chromosomes; Sex Determination Processes; Y chromosome; Y chromosomes
• ISSN: 1617-4615; 1617-4623
• DOI: 10.1007/s00438-007-0243-z

Sex chromosomes in flowering plants evolved recently and many of them remain homomorphic, including those in papaya. We investigated the chromosomal location of papaya's small male specific region of the hermaphrodite Y (Yh) chromosome (MSY) and its genomic features. We conducted chromosome fluorescence in situ hybridization mapping of Yh-specific bacterial artificial chromosomes (BACs) and placed the MSY near the centromere of the papaya Y chromosome. Then we sequenced five MSY BACs to examine the genomic features of this specialized region, which resulted in the largest collection of contiguous genomic DNA sequences of a Y chromosome in flowering plants. Extreme gene paucity was observed in the papaya MSY with no functional gene identified in 715 kb MSY sequences. A high density of retroelements and local sequence duplications were detected in the MSY that is suppressed for recombination. Location of the papaya MSY near the centromere might have provided recombination suppression and fostered paucity of genes in the male specific region of the Y chromosome. Our findings provide critical information for deciphering the sex chromosomes in papaya and reference information for comparative studies of other sex chromosomes in animals and plants.