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The origin of the non‐recombining region of sex chromosomes in Carica and Vasconcellea
Author(s) -
Wu Xia,
Wang Jianping,
Na JongKuk,
Yu Qingyi,
Moore Richard C.,
Zee Francis,
Huber Steven C.,
Ming Ray
Publication year - 2010
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2010.04284.x
Subject(s) - carica , biology , allele , genetics , haplotype , monophyly , phylogenetic tree , evolutionary biology , gene , clade , botany
Summary Carica and Vasconcellea are two closely related sister genera in the family Caricaceae, and were once classified as two sections under Carica . Sex chromosomes have been found in papaya and originated approximately 2–3 million years ago. The objectives of this study were to determine whether sex chromosomes have evolved in Vasconcellea . Six X/Y gene pairs were cloned, sequenced and analyzed from three dioecious, one trioecious and one monoecious species of Vasconcellea . The isolation of distinctive X and Y alleles in dioecious and trioecious species of Vasconcellea demonstrated that sex chromosomes have evolved in this genus. Phylogenetic analyses indicated a monophyletic relationship between the X/Y alleles of Carica and those of Vasconcellea . Distinctive clusters of X/Y alleles were documented in V. parviflora and V. pulchra for all available gene sequences, and in V. goudatinana and V. cardinamarcensis for some X/Y alleles. The X and Y alleles within each species shared most single nucleotide polymorphism haplotypes that differed from other species. Limited evidence of gene conversion was documented among the X/Y alleles of some species, but was not sufficient to cause the evolutionary patterns reported herein. The Carica and Vasconcellea sex chromosomes may have originated from the same autosomes bearing the X allelic form that still exist in the monoecious species V. monoica , and have evolved independently after the speciation event that separated Carica from Vasconcellea. Within Vasconcellea , sex chromosomes have evolved at the species level, at least for some species.