大血藤的rDNA ITS序列分析

采用PCR直接测序法,对大血藤科植物大血藤9个样品和单叶血藤1个样品进行nrDNA ITS序列测定和分析。研究结果发现大血藤和单叶血藤ITS的长度为634～635bp;其中ITS1为233bp,5.8S为163bp,ITS2的长度为238～239bp。以串果藤为外类群构建最大简约树,大血藤和单叶血藤的10个样品构成一个单系类群,并且得到了自展值100%的支持。根据大血藤在中国的分布情况,单叶血藤在陕西的出现,以及分子数据的分析结果,华中区系可能是大血藤的现代分布中心,而且大血藤分布呈华中区系、华东区系、西南区系地带性的分化。这种地带性分化,更多的跟其地理、气候、环境等协同进化有关。陕西宁陕县的大血藤和单叶血藤这两个样品,ITS长度均为635bp,核苷酸差异值只有0.0032。与其他样品相比,单叶血藤与大血藤(陕西)在ITS2的一个信息位点同时发生了颠换,并且都有碱基插入现象,表现出地理特异性。单叶血藤与大血藤其它9个样品的核苷酸差异值仅在0.32%～2.31%之间,远小于大多数被子植物属下种间的核苷酸差异值1.2%～10.2%。分子数据支持将单叶血藤合并到大血藤中去。

Analysis of rDNA ITS sequences of Sargentodoxa cuneata

By PCR products sequencing methods,nuclear ribosomal DNA ITS regions of nine samples of Sargentodoxa cuneata and one sample of S.simplicifolia were sequenced and analyzed. The results showed that the ITS length of S.cuneat and S.simplicifolia was from 634bp to 635bp. The ITS1 was 163bp and the ITS2 was from 238bp to 239bp. Based on the maximum parsimony (MP) trees as Sinofranchetia chinensis was the outgroup,all the ten samples of S.cuneata and S.simplicifolia formed a monophyletic clade and got 100% bootstrap support. According to the present distribution of S.cuneata and S.simplicifolia in China,the apperancance of S.simplicifolia in Shaanxi Province,as well as the analyzed results of molecule data,the flora of Central China was probably modern distributing center of S.cuneata. The distribution of S.cuneata presented zonal differentiation of the flora of Central China,East China and South-West China. The zonal differentiation was more related with the co-evolution of the geography,climate and environment and so on. The ITS length of the samples of S.cuneata and S.simplicifolia coming from Ningshan,Shaanxi Province was 635bp. Their pairwise divergence was only 0.003 2. Compared with other samples,at the same site in ITS2 of S.simplicifilia and S.cuneata (shaanxi) a base was transversioned,at another site a base was inserted. The ITS data showed their geography special. The pairwise percentage divergences in the sample of S.simplicifolia and nine samples of S.cuneata were from 0.32% to 2.31% and were much lower than the pairwise percentage divergences among species of most angiosperm,which were from 1.2% to 10.2%.So it would be better if S.simplicifilia was merged with S.cuneata based on ITS data.