Independent origins of tetraploid cryptic species in the fern Ceratopteris thalictroides
Independent origins of tetraploid cryptic species in the fern Ceratopteris thalictroides
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DOI：
10.1007/s10265-006-0032-5
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发表时间：
2007-01-01
影响因子：
2.8
通讯作者：
Watano, Yasuyuki
中科院分区：
文献类型：
--
作者：
Adjie, Bayu;Masuyama, Shigeo;Watano, Yasuyuki
水蕨Ceratopteris thalictroides（L.）Brongn是一种四倍体蕨类植物，至少包含三种隐种，即南方型、北方型和第三型。本研究结合了三个二倍体种和三个隐蔽种的叶绿体DNA和核DNA序列的数据。thalictroides的研究，以解开隐藏种的起源，特别是在水蕨属的二倍体和四倍体类群之间的网状关系。在三个二倍体种中，C. cornuta的cpDNA与四倍体第三类植物的cpDNA完全相同，该二倍体种可能是四倍体第三类植物的母系祖先。对拟南芥LEAFY基因（CLFY 1）同源序列的分析在水蕨属中发现了10个等位基因，其中在C.海栖藻CLFY1基因的无根树揭示了四个簇。每个隐种在CLFY1位点表现出固定的杂合性，并有两个等位基因来自CLFY1树的不同聚类。综合考虑隐种的cpDNA序列、CLFY1基因型和CLFY1基因树，推测隐种的CLFY1基因可能是隐种。thalictroides起源于独立的异源多倍体化事件，包括C。cornuta和两个未知的假设二倍体物种。
Ceratopteris thalictroides (L.) Brongn is a tetraploid fern species that contains at least three cryptic species, the south, the north and the third type. In this study we combined data from both chloroplast DNA (cpDNA) and nuclear DNA sequences of three diploid species and three cryptic species of C. thalictroides to unravel the origin of the cryptic species, particularly of the reticulate relationships among the diploid and tetraploid taxa in the genus Ceratopteris. Of the three diploid species examined, C. cornuta had cpDNA identical to that of the tetraploid third type plants, and this diploid species is a possible maternal ancestor of the tetraploid third type. Analysis of the homologue of the Arabidopsis thaliana LEAFY gene (CLFY1) identified ten alleles in the genus Ceratopteris, with six alleles found in C. thalictroides. The unrooted tree of the CLFY1 gene revealed four clusters. Each cryptic species showed fixed heterozygosity at the CLFY1 locus and had two alleles from different clusters of the CLFY1 tree. Consideration of the cpDNA sequences, CLFY1 genotypes of the cryptic species and CLFY1 gene tree in concert suggested that the cryptic species of C. thalictroides had originated through independent allopolyploidization events involving C. cornuta and two unknown hypothetical diploid species.