较小拟毛刺线虫不同群体的形态及分子特征比较研究

Morphological and molecular characterization of Paratrichodorus minor populations from China

毛刺类线虫系一类重要的植物外寄生线虫,其内包括一些可传播植物病毒的种类。本研究基于形态学和rDNA分子特征从我国海南儋州、云南呈贡和昆明、福建厦门等植物根围土壤样品中分离鉴定出8个较小拟毛刺线虫(Paratrichodorus minor)群体;通过对种群数量较大的海南儋州群体与福建厦门群体的形态及测量值比较,发现不同地理群体间主要形态测量值存在一定差异;各群体18S RNA区、r DNA-ITS1区、r DNA-ITS2区和28S RNA基因中D2D3区序列与Gen Bank已登录的较小拟毛刺线虫不同群体相应序列(AJ438053、AJ438054及AJ438056;KJ934126;JN123380和JN123381;JN123396和KJ513001)相似度分别介于99.1%~99.9%、95.8%~96.3%、99.5%~99.8%和99.4%~99.9%。对上述较小拟毛刺线虫群体r DNA-ITS1区、r DNA-ITS2区和28S RNA基因中D2D3区序列比较和酶切分析显示,该3段序列在较小拟毛刺线虫种内群体间都较为保守。其中28S RNA基因中D2D3区序列在种内群体稳定,种间群体有明显的差异,系毛刺类线虫鉴定一较好的分子靶标。有关结果对较小拟毛刺线虫的鉴定及鉴别有直接的指导意义。

Trichodorids constitute an important group of ectoparasitic nematodes of plant,in which some of the species can transmit various viruses to economically important crops. In this study,8 Paratrichodorus populations from the rhizosphere of eggplant,chinaberry,lettuce,peach,pear,walnut and longan in Hainan（ Danzhou）,Yunnan（ Chenggong and Kunming）,and Fujian（ Xiamen） regions of China were identified as P. minor based on the morphological and rDNA characteristics. Morphological and morphometrical comparisons of Hainan（ Danzhou） and Fujian（ Xiamen） populations showed certain intra-species morphometric variations.The sequence similarity of 18 S RNA gene,rDNA-ITS1,rDNA-ITS2 and D2 D3 region of 28 S RNA gene among P. minor populations used in this study and those submitted in GenBank（ AJ438053,AJ438054 and AJ438056;KJ934126; N123380 and JN123381; JN123396 and KJ513001） ranged in 99. 1%-99. 9%,95. 8%-96. 3%,99.5%-99.8% and 99.4%-99.9%,respectively. PCR-RFLP of ITS1,ITS2 region of rDNA and D2 D3 region of28 S RNA gene revealed the consistency among these intra-species populations. D2 D3 region of 28 S RNA gene sequences are stable within the intra-species populations and have clear differences among inter-species of trichodorid nematodes which is a good molecular marker for identification of trichodorid nematodes. These results indicate that rDNA sequences can provide useful information for molecular identification of P. minor.