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Evolution of morphology, ecology and chromosome in the genus Stevia : Molecular phylogenetic approaches

甜菊属形态、生态和染色体的进化：分子系统发育方法

基本信息

批准号：
07454235
负责人：
YAHARA Tetsukazu
金额：
$ 4.99万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

The purpose of this study is to estimate phylogenetic relationships among Stevia and its relatives using molecular data and examine evolutionary correlations of morphological, ecological and chromosomal traits based on the phylogenetic tree.The phylogenetic tree estimated from matK sequence data suggested that Carphocaete is a sister group of Stevia and n=12 is the ancestral chromosome number in the genus Stevia. Ageratum (n=10), which has been regarded as a relative of Stevia, was clustered not with Stevia but with genera with n=10. Morphological similarity between Stevia and Ageratum is considered to be a result of convergent evolution. Mcvaugiella (n=13), which has also been regarded as a relative of Stevia, was clustered not with Stevia but with Pachytamnus with n=17. This evidence suggests than n=12 in Stevia and n=13 in Mcvaugiella are independently derived from n=17.Phylogenetic relationships within the genus Stevia were examined using sequence data of ITS.An obtaiend tree showed that (1) an annual species S.aschenborniana (n=12) is basal to all other species examined, (2) a clade of shurubby species (n=12) is branched next, and then (3) perennial species diverged to two clades, one having n=12 and the other having n=11 and 12.Phylogenetic evidence showed that evolutionary changes in chromosome number and generation time are correlated, but those in chromosome number and genome size are not dorrelated.Evolutionary changes to annuality are correlated with those to self-pollination, but reduction in flower size was not correlated with changes to annuality or self-pollination.

本研究的目的是利用分子生物学数据对甜菊属及其近缘种的系统发育关系进行估计，并在系统发育树的基础上对形态、生态和染色体性状的进化相关性进行分析，结果表明甜菊属的Carphocaete是甜菊属的姐妹类群，其祖先染色体数目为n=12。胜红蓟属（n=10）被认为是甜叶菊的近缘种，但不与甜叶菊聚类，而是与n=10的属聚类。甜菊属和胜红蓟属之间的形态相似性被认为是趋同进化的结果。Mcvaugiella（n=13）也被认为是甜叶菊的亲戚，不与甜叶菊聚类，而是与Pachytamnus（n=17）聚类。利用ITS序列分析了甜菊属植物的系统发育关系，结果表明：（1）一年生种S.aschenborniana（n= 12）是所有被研究的种的基部，（2）一个分支shurgiums（n = 12）是其后的分支，（3）多年生植物分化为n=12和n=11、12的两个分支。系统发育证据表明，染色体数目的进化变化与世代时间相关，而染色体数目和基因组大小的进化变化不相关。一年生植物的进化变化与自花授粉的进化变化相关，但花的大小的减少与一年生或自花授粉的变化无关。