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bioRxiv · 10.1101/2022.12.29.522208

Ongoing rapid evolution of a post-Y region revealed by chromosome-scale genome assembly of a hexaploid monoecious persimmon (Diospyros kaki)

Horiuchi, A.·Masuda, K.·Shirasawa, K.·Onoue, N.·Fujita, N.·Ushijima, K.·Akagi, T.
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Abstract

Sex chromosomes have evolved independently in many plant lineages. They have often undergone rapid structural degeneration and extension of non-recombining regions, which is conventionally considered to be strongly associated with the expression of sexually dimorphic traits. In this study, we assembled a monoecious hexaploid persimmon (Diospyros kaki) in which the Y chromosome had lost its function in male determination. Comparative genomic analysis among D. kaki and its dioecious relatives revealed that the non-functional Y chromosome (Ym) via silencing of the sex-determining gene, OGI, arose approximately two million years ago. Comparative analyses of the whole X and Ym chromosomes suggested that the non-functional male-specific region of the Y-chromosome (MSY), or post-MSY, retained certain conserved characteristics of the original functional MSY. Specifically, comparison of the functional MSY in D. lotus and the non-functional post-MSY in D. kaki indicated that the post-MSY had been rapidly rearranged mainly via ongoing transposable element bursts, as well as in the functional MSY. These results suggest a novel interpretation that the rapid evolution of the post-MSY (and possibly also MSYs in dioecious Diospyros species) might reflect the ancestral genomic properties of these regions, rather than the evolution of male-determining functions and/or sexually dimorphic traits.

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Horiuchi, A., Masuda, K., Shirasawa, K., Onoue, N., Fujita, N., Ushijima, K., Akagi, T.. 2022-12-30. Ongoing rapid evolution of a post-Y region revealed by chromosome-scale genome assembly of a hexaploid monoecious persimmon (Diospyros kaki). https://doi.org/10.1101/2022.12.29.522208

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