基于ITS序列探讨南瓜属植物系统发育
Phylogeny of Cucurbita Based on ITS sequence data
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摘要: 基于ITS序列对南瓜属3个种(中国南瓜、美洲南瓜和黑籽南瓜)的系统发育进行了研究。结果表明,ITS1全长188～191bp,ITS2全长251～263bp;南瓜ITS1序列的变异位点数为33,占ITS1全序列的17.55%,ITS1序列的信息位点数为24,占ITS1全序列的12.77%;南瓜ITS2序列的变异位点数为45个,占ITS2全序列的17.93%,ITS2的信息位点数为31个,占ITS2全序列的12.35%;ITS1的G+C含量变化范围为51.60%～54.50%,ITS2的G+C含量变化范围为53.78%～56.98%;基于ITS1和ITS2分别构建的系统树可以看出,中国南瓜和美洲南瓜的亲缘关系较近,与黑籽南瓜的亲缘关系较远。Abstract: The relationships and differences among the species,Cucurbita,pepo and ficifofia (Cucurbitaceae:Cucurbita),were examined using data from the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA. The ITS sequences were obtained from Cucurbita,pepo and ficifofia 3 species. The results showed that,within Cucurbita,ITS1 was 188-191bp (C. Cucurbita,C. pepo and C. ficifofia) and ITS2 ranged from 251-263bp (C. Cucurbita,C. pepo and C. ficifofia). There were 33 variable positions (17.55%) and 24 informative sites (12.77%) within Cucurbita found in the ITS1 sequences,while 45 variable positions (17.93%) and 31 informative sites (12.35%) found in the ITS2 sequences.The G+C content of ITS1 was 51.60% to 54.50% and that of ITS2 ranged from 53.78% to 56.98%.The resulting trees from the ITS1 and ITS2 sequences showed that the relationship between C. Cucurbita and C. pepo was closer than that between C. Cucurbita and C. ficifofia.
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