The Y chromosome in the liverwort Marchantia polymorpha has accumulated unique repeat sequences harboring a male-specific gene.
The haploid liverwort Marchantia polymorpha has heteromorphic sex chromosomes, an X chromosome in the female and a Y chromosome in the male. We here report on the repetitive structure of the liverwort Y chromosome through the analysis of male-specific P1-derived artificial chromosome (PAC) clones, pMM4G7 and pMM23-130F12. Several chromosome-specific sequence elements of approximately 70 to 400 nt are combined into larger arrangements, which in turn are assembled into extensive Y chromosome-specific stretches. These repeat sequences contribute 2-3 Mb to the Y chromosome based on the observations of three different approaches: fluorescence in situ hybridization, dot blot hybridization, and the frequency of clones containing the repeat sequences in the genomic library. A novel Y chromosome-specific gene family was found embedded among these repeat sequences. This gene family encodes a putative protein with a RING finger motif and is expressed specifically in male sexual organs. To our knowledge, there have been no other reports for an active Y chromosome-specific gene in plants. The chromosome-specific repeat sequences possibly contribute to determining the identity of the Y chromosome in M. polymorpha as well as to maintaining genes required for male functions, as in mammals such as human.
Okada
S
S
Laboratory of Plant Molecular Biology, Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
Sone
T
T
Fujisawa
M
M
Nakayama
S
S
Takenaka
M
M
Ishizaki
K
K
Kono
K
K
Shimizu-Ueda
Y
Y
Hanajiri
T
T
Yamato
K T
KT
Fukuzawa
H
H
Brennicke
A
A
Ohyama
K
K
D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D022201:Chromosomes, Artificial; D018744:DNA, Plant; D017404:In Situ Hybridization, Fluorescence; D019684:Magnoliopsida / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014998:Y Chromosome
D018744:DNA, Plant