|Title:||石松類和瓶爾小草葉綠體matK 基因之鑑定與matK 基因的演化
The Evolution of Chloroplast matK Genes, Including Identification of New Homologues from Ophioglossum petiolatum and Two Lycophytes
|Keywords:||Chloroplast matK;Lycopodiella cernua;Selaginella doederleinii;Ophioglossum petiolatum;Evolution||Issue Date:||2004||Publisher:||臺北市：國立台灣大學生態學與演化生物學研究所||Journal Volume:||49||Journal Issue:||四||Start page/Pages:||-||Source:||Taiwania||Abstract:||
The introns of chloroplast trnKUUU belong to Group II introns and contain an open
reading frame denoted as matK. The trnK5’-matK-trnK3’ structure is consistent in almost all examined
higher land plants and in Characeae, but not in other green algae examined. The putative gene product
MatK is the only maturase in chloroplasts. Functional chloroplast matK genes are retained even in the
nonphotosynthetic parasite, Epifagus virginiana and the fern, Adiantum capillus-veneris, in which
chloroplast genome rearrangement has left matK free-standing, apart from trnK exons. Among lower
land plants, the chloroplasts of Psilotum, mosses and liverworts all have trnK5’-matK-trnK3’ structure,
but matK is a pseudogene in hornwort Anthoceros formosae. In this study we found a clear
trnK5’-matK-trnK3’ structure in Ophioglossum petiolatum, Lycopodiella cernua and Selaginella
doederleinii, but PCR with degenerate primers failed to amplify any trnK or matK fragments from
other ferns and fern allies. However, dot blot hybridization showed distinct signals in these plants that
failed to amplify matK fragments by PCR, indicating that the matK sequences in those taxa may be too
divergent to amplify by an ordinary PCR approach. RT-PCR results showed matK genes are expressed
in Ophioglossum petiolatum and Lycopodiella cernua, but no signal was detected in Selaginella
doederleinii. Overall, the expression patterns of matK are not consistent in lower land plants.
Phylogenetic analysis of matK sequence showed that Pinus, Ginkgo, and Cycas form a monophyletic
group, which is sister to angiosperms. Together, they form a clade that is sister to Gnetales. This ad
hoc reconstruction is likely due to the high evolutionary rate in matK.
|Appears in Collections:||生態學與演化生物學研究所|
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