西藏自治区色季拉山高寒草甸牧草根腐线虫的鉴定

Identification of lesion nematode in alpine cold meadow of Color Gerahs Mountain,Tibet

在西藏自治区色季拉山高寒草甸土壤线虫群落调查期间,从高山嵩草(Kobresia pygmaea)根际土壤中分离得到一种根腐线虫。通过形态特征观察和分子序列比对,将其鉴定为刻痕短体线虫(Pratylenchus crenatus)。其主要特征:唇环3个,口针长15.6～16.2μm,口针基部球前缘略凹,侧线6条,V值为82.5～83.2,尾圆柱形,末端环纹清晰。对该线虫rDNA的3个区段(18S部分序列、28SD2D3区和ITS区)进行特异性扩增和测序,分别得到902、774和1 013bp的序列。将所获得的序列在GenBank数据库上进行BLAST比对,结果显示:此线虫群体与刻痕短体线虫群体的相似度分别为97.4%～99.8%、97.4%～97.8%和90.2%～99.8%。贝叶斯推断法构建的系统进化树显示:本研究的线虫群体与刻痕短体线虫聚为高度支持的分支,进一步确定此线虫群体为刻痕短体线虫。本研究获得刻痕短体线虫中国群体的分子数据。该刻痕短体线虫是西藏自治区的新纪录种。高山嵩草是刻痕短体线虫的新寄主。

During the survey of soil nematodes in an alpine cold meadow of Color Gerahs Mountain,Tibet,a species of root lesion nematode was obtained from Kobresia pygmaea rhizosphere soil.Based on morphological characterization and molecular analysis,the species was identified as Pratylenchus crenatus.The nematode was characterized by a flatten lip with 3 annuli,stylet length of 15.6-16.2μm,stylet knobs with concave anterior face,lateral fields with 6 lines,vulva position at 82.5%-83.2%of body length,and a cylindrical tail with distinct striated terminus.Amplification of 3 rDNA segments(partial 18S,28S D2D3 and ITS sequences)generated PCR fragments with sizes of 902 bp,774 bp and 1 013 bp,respectively.The similarities between the 3 rDNA segments in this study and those deposited in the GenBank database were 97.4%-99.8%,97.4%-97.8%and 90.2%-99.8%,respectively.Bayesian inference method was used to construct the phylogenetic relationship of P.crenatus in China and other regions,as well as other associated species.All sequences of P.crenatus including that of this study formed a highly supported clade,which further confirmed that this population was P.crenatus.Molecular information of Chinese P.crenatus population was obtained in this study.P.crenatus was a new record in Tibet,southwest China,and K.pygmaea was founded to be a new host plant of P.crenatus.