不同产地瓠瓜品种ITS序列的遗传多样性分析

对国产29个瓠瓜也Lagenariasiceraria（Molina）Standl.页品种的ITS序列进行了扩增及测序,并结合引自GenBank的国产9个瓠瓜品种以及国外6个瓠瓜品种和3个同属种类的ITS序列,对它们的ITS序列长度和GC含量以及变异位点进行比较,在此基础上构建系统发育树并对47个样本间的遗传关系进行研究。结果显示：供试47个样本的ITS序列均由ITS1、5.8SrDNA及ITS2组成,各样本间的ITS序列长度、GC含量以及变异位点差异明显。国产38个瓠瓜品种的ITS序列（包括ITS1、5.8SrDNA及ITS2）长度为619-627bp、GC含量为58.00%-63.32%；国外9个样本的ITS序列长度为591-626bp,GC含量为54.17%-63.26%。序列比对结果显示：国产38个瓠瓜品种的ITS序列同源率为84.6%-100.0%,包含221个变异位点；其中,来源于山东的品种‘砧木2’（‘ZhenmuNo.2’）的ITS序列包含的变异位点最多,与其他品种间的同源率也最低。在系统发育树上,国产38个瓠瓜品种可分为3个分支,来源于山东的品种‘砧木2’和来源于河南的品种‘西瓜砧木1’（‘XiguazhenmuNo.1’）各自聚为第1和第2分支；其余36个品种聚为第3分支。而供试的47个样本则可分为2个分支和5个亚组,第1分支可分为2个亚组,包括国产品种‘砧木2’和产自日本的2个品种；第2分支包含的44个样本则进一步分为3个亚组,国产品种‘西瓜砧木1’和产自法国的品种‘白花瓠瓜’（‘White-floweredgourd’）各自聚为第1和第2亚组,其余的42个样本聚为第3亚组。研究结果表明：供试的不同产地瓠瓜品种间存在丰富的遗传变异和地理分化现象,其ITS序列差异与地理分布有一定关系。

Genetic diversity analysis on ITS sequence of Lagenaria siceraria cultivars from different origins

ITS sequence of 29 cultivars of Lagenaria siceraria （Molina） Standl. in China was amplified and sequenced, and combined with that of 9 cultivars of L. siceraria in China, 6 cultivars of L. siceraria and 3 congeneric species abroad from GenBank, length, GC content and variation site of their ITS sequence were compared. On this basis, phylogenetic tree was constructed and genetic relationship among 47 samples was researched. The results show that ITS sequence of 47 samples all includes ITS1, 5. 8S rDNA and ITS2, and there are obvious differences in length, GC content and variation site of ITS sequence among different samples. Length of ITS sequence （including ITS1, 5. 8S rDNA and ITS2） of 38 cultivars of L. siceraria in China is 619-627 bp, and their GC content is 58. 00% -63. 32% . While ITS sequence length and GC content of 9 samples abroad are 591 -626 bp and 54. 17% -63. 26% , respectively. The result of sequence alignment shows that homological rate of ITS sequence of 38 cultivars of L. siceraria in China is 84. 6% -100. 0% , which includes 221 variation sites. In which there are the most variation sites of ITS sequence and the smallest homological rate in cultivar ‘Zhenmu No. 2’ from Shandong as compared with other cultivars. According to the phylogenetic tree, 38 cultivars of L.siceraria in China can be divided into 3 branches, cultivar ‘Zhenmu No. 2’ from Shandong and cultivar‘Xiguazhenmu No. 1’ from He’ nan are clustered in the first and second branches, respectively, and other 36 cultivars are clustered in the third branch. While 47 samples tested are divided into 2 branches and 5 subgroups. The first branch can be divided into two subgroups, which includes cultivar ‘Zhenmu No. 2’ in China and two cultivars in Japan; and the second branch includes 44 samples which can be divided into 3 subgroups, in which, cultivar ‘ Xiguazhenmu No. 1’ in China and cultivar ‘ White-flowered gourd’ in France are clustered in the first and second subgroups, respectively, and other 42 cultiv