title: Gene organization of the liverwort Y chromosome reveals distinct sex chromosome evolution in a haploid system.
abstract: Y chromosomes are different from other chromosomes because of a lack of recombination. Until now, complete sequence information of Y chromosomes has been available only for some primates, although considerable information is available for other organisms, e.g., several species of Drosophila. Here, we report the gene organization of the Y chromosome in the dioecious liverwort Marchantia polymorpha and provide a detailed view of a Y chromosome in a haploid organism. On the 10-Mb Y chromosome, 64 genes are identified, 14 of which are detected only in the male genome and are expressed in reproductive organs but not in vegetative thalli, suggesting their participation in male reproductive functions. Another 40 genes on the Y chromosome are expressed in thalli and male sexual organs. At least six of these genes have diverged X-linked counterparts that are in turn expressed in thalli and sexual organs in female plants, suggesting that these X- and Y-linked genes have essential cellular functions. These findings indicate that the Y and X chromosomes share the same ancestral autosome and support the prediction that in a haploid organism essential genes on sex chromosomes are more likely to persist than in a diploid organism.
authors: Laboratory of Plant Molecular Biology, Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors: Katsuyuki T
authors: KT
authors: Yamato
authors: Kimitsune
authors: K
authors: Ishizaki
authors: Masaki
authors: M
authors: Fujisawa
authors: Sachiko
authors: S
authors: Okada
authors: Shigeki
authors: S
authors: Nakayama
authors: Mariko
authors: M
authors: Fujishita
authors: Hiroki
authors: H
authors: Bando
authors: Kohei
authors: K
authors: Yodoya
authors: Kiwako
authors: K
authors: Hayashi
authors: Tomoyuki
authors: T
authors: Bando
authors: Akiko
authors: A
authors: Hasumi
authors: Tomohisa
authors: T
authors: Nishio
authors: Ryoko
authors: R
authors: Sakata
authors: Masayuki
authors: M
authors: Yamamoto
authors: Arata
authors: A
authors: Yamaki
authors: Masataka
authors: M
authors: Kajikawa
authors: Takashi
authors: T
authors: Yamano
authors: Taku
authors: T
authors: Nishide
authors: Seung-Hyuk
authors: SH
authors: Choi
authors: Yuu
authors: Y
authors: Shimizu-Ueda
authors: Tsutomu
authors: T
authors: Hanajiri
authors: Megumi
authors: M
authors: Sakaida
authors: Kaoru
authors: K
authors: Kono
authors: Mizuki
authors: M
authors: Takenaka
authors: Shohei
authors: S
authors: Yamaoka
authors: Chiaki
authors: C
authors: Kuriyama
authors: Yoshito
authors: Y
authors: Kohzu
authors: Hiroyuki
authors: H
authors: Nishida
authors: Axel
authors: A
authors: Brennicke
authors: Tadasu
authors: T
authors: Shin-i
authors: Yuji
authors: Y
authors: Kohara
authors: Takayuki
authors: T
authors: Kohchi
authors: Hideya
authors: H
authors: Fukuzawa
authors: Kanji
authors: K
authors: Ohyama
mesh_terms: D001483:Base Sequence; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics*; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D017343:Genes, Plant / Q000235:genetics*; D006238:Haploidy; D035926:Hepatophyta / Q000235:genetics*; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA