title: Dynamic transposable element accumulation in the nascent sex chromosomes of papaya.
abstract: From their inception, Y chromosomes in plants and animals are subjected to the powerful effects of Müller's ratchet, a process spurred by suppression of recombination that results in a rapid accumulation of mutations and repetitive elements. These mutations eventually lead to gene loss and degeneration of the Y chromosome. Y chromosomes in mammals are ancient, whereas most sex chromosomes in plants and many in insects and fish evolved recently. Sex type in papaya is controlled by a pair of nascent sex chromosomes that evolved around 7 million years ago. The papaya X and Yhwere recently sequenced, providing valuable insight into the early stages of sex chromosome evolution. Here we discuss the fruits of this work with a focus on the repeat accumulation, gene trafficking and promiscuous DNA sequences found in the slowly degenerating Yhchromosome of papaya.
authors.affiliation: Department of Plant Biology; University of Illinois at Urbana-Champaign; Urbana, IL USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Vanburen
authors.forename: Ray
authors.initials: R
authors.lastname: Ming
keywords: Y chromosome degeneration; chloroplast genomic DNA; gene loss and gain; heterochromatin; retrotransposons