Bryological and Lichenological Section/ABLS
Tseng, Yu-Hsin , Gan, Ya-Wen , Hu, Jer-Ming .
Identification of ORF-162 homologues from four liverworts in Taiwan.
SEX of liverwort Marchantia polymorpha is determined by the sex chromosomes, an X in female and a Y in male, in its halploid genome. Previous study showed that the Y chromosome of M. polymorpha contains unique repetitive sequences with an ORF named ORF162, based on Japan's plant materials. This gene is absent in the females and encodes a putative RING finger protein and is transcribed specifically in male sexual organ. However, our results revealed that the sequences of ORF162 are also present in the female genome of M. polymorpha in Taiwan. We have identified twelve independent clones from female genomes of M. polymorpha and one of them has intact open reading frame, and others are likely pseudogenes. We also identified additional ORF162-like sequences from one monoicous (Reboulia hemisphaerica) and two dioicous (males and females of Marchantia emarginata ssp. tosana and males of Marchantia paleacea) species of Marchantiales, and the data show that the sequences are present in all examined species, even though many of them are likely pseudogenes as they have prematured stop codons in the sequences. All of the ORF162 homologous sequences share extremely high similarities in coding and 5’ untranscribed regions among these species. This suggests that either the function of ORF162 is highly conserved or the ORF162 homologues were newly acquired after the separation of Marchantiaceae and Aytoniaceae (represented by R. hemisphaerica). Finally we speculate that the absence of ORF162 in female genome of Japan's M. polymorpha is likely due to deletions during the evolutionary process, whereas the populations in Taiwan somehow preserves this plesiomorphic character.
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1 - National Taiwan University, Institute of Ecology and Evolutionary Biology, Rm1227, Life Science Building, 1 Roosevelt Road, Sect.4, Taipei, 106, Taiwan
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM