旱稻孢囊线虫在广西的发生及其rDNA-ITS异质性分析

Occurence of Heteroderaelachistain Guangxi Region and Its Intra-species Heterogeneity in rDNA-ITS Region

2011年,从广西龙胜梯田的水稻根系和稻田土壤中分离到一种孢囊线虫。该线虫形态特征与已报道的旱稻孢囊线虫（Heterodera elachista）相符,其rDNA-ITS序列与GenBank中旱稻孢囊线虫的rDNA-ITS序列相似性为97.7%~99.3%。rDNA-ITS分子发育树表明该线虫与旱稻孢囊线虫以100%的置信度及较小的遗传距离形成一个单系,据此将该线虫鉴定为旱稻孢囊线虫。进一步对本研究获得的10条旱稻孢囊线虫rDNA-ITS区序列及Tanha Maafi等报道的1条旱稻孢囊线虫rDNA-ITS序列（AF498391）的酶切位点进行分析,结果发现AluⅠ、AvaⅠ、MvaⅠ和RsaⅠ4个内切酶的酶切位点在11条序列中完全一致,而Bsh1236Ⅰ、BsuRⅠ和CfoⅠ3种酶的酶切位点存在变异,其中Bsh1236Ⅰ和BsuRⅠ有2种变异型,CfoⅠ则有3种变异型,表明旱稻孢囊线虫的rDNA-ITS序列存在DNA异质性。

In 2011, a cyst nematode was isolated from rice roots and soils in Longsheng Terrace of Guangxi Region, China. Morphological characteristics of the cyst nematode were consistent with previous descriptions of Heterodera ela- chista. The rDNA ITS sequences of the cyst nematode and H. elachista in GenBank shared 97.7%-99.3% identities. The phylogenetic tree based on rDNA-ITS showed that the cyst nematode was in the same monophyletic clade as H. elachista with 100% support and short branch differences. The results indicated the cyst nematode was Heterodera elachista. The restriction enzyme cutting sites of ten rDNA-ITS sequences of H. elachista amplified and the one reported by Tanha Maafi （GenBank accession number： AF498391） were analyzed. The restriction enzyme cutting sites of Alu I , Ava I , Mva I and Rsa I in these 11 sequences were identical, however there were 2 different patterns after Bsh 1236 I and BsuR I digestion, respectively, and 3 different patterns after Cfo I digestion. The results show intra-species heterogeneity in rDNA-ITS region exists in H. elachista.