Yasui Y, Ohnishi O
Plant Germ-Plasm Institute, Faculty of Agriculture, Kyoto University, Japan.
Genes Genet Syst. 1998 Aug;73(4):201-10. doi: 10.1266/ggs.73.201.
The DNA sequences of the internal transcribed spacer (ITS) region of the rRNA gene were determined in 20 taxa of 12 species of Fagopyrum. By comparing the sequence data and constructing phylogenetic trees, the phylogenetic relationships among the Fagopyrum species were established. The sequences of ITS (ITS1 and ITS2) were about 3-7 times more variable than those of the 5.8S subunit of the rRNA gene. The classification of Fagopyrum species based on the DNA sequences of the rRNA gene almost coincides with the classification based on morphology, allozyme variability, and nucleotide sequences of the rbcL-accD region of the chloroplast DNA. A close relationship of F. lineare with the F. statice-F. leptopodum clade was suggested and this was strongly supported by a 68-bp gap in ITS1 found in these three species. A tetraploid F. cymosum from Kathi, India, has two distinct rRNA genes probably on homoeologous chromosomes, and was distinguished from the clade of other diploid/tetraploid F. cymosum with a high bootstrap value. This strengthened the hypothesis of the polyphyletic origin of the tetraploid F. cymosum.
测定了12种荞麦属植物20个分类群的核糖体RNA基因内转录间隔区（ITS）的DNA序列。通过比较序列数据并构建系统发育树，确定了荞麦属植物之间的系统发育关系。ITS（ITS1和ITS2）序列的变异性比rRNA基因5.8S亚基的序列高约3至7倍。基于rRNA基因DNA序列的荞麦属植物分类与基于形态学、等位酶变异性和叶绿体DNA的rbcL-accD区域核苷酸序列的分类几乎一致。线性荞麦与紫花野荞麦-细柄野荞麦分支关系密切，这在这三个物种的ITS1中发现的68个碱基对的缺口得到了有力支持。来自印度卡西的四倍体金荞麦有两个可能位于同源染色体上的不同rRNA基因，并以高自展值与其他二倍体/四倍体金荞麦分支区分开来。这强化了四倍体金荞麦多系起源的假说。
