Abstract：Rotylenchulus reniformis is a semi-endoparasitic nematode, which widely distributes in tropical and subtropical area of the world, and is pathogenic nematodes of many vegetables and tropical fruit trees. Our research was focus on identification and phylogenetic relationship among different geographical populations of reniform nematode. To characterize the genetic diversity of intra-species populations of Rotylenchulus reniformis, sequence variations of COII- LrRNA mitochondrial DNA (mtDNA) between individuals and 3 intra-species populations of reniform nematode from Zhejiang (ZJ), Fujian (FJ) and Chongqing (CQ) were analyzed based on DNA sequence analysis technology. The result showed that the length of COII-LrRNA gene region ranged from 557 to 563 bp using primer 1108 and C2F3-R. The average content of A, T, C and G were 32.6%, 52.9%, 4.5% and 10.0%, respectively. The content of A+T was 85.5%, and it was much higher than that of G+C content. Obvious genetic diversity was found from the amplified region. All 389 conserved sites, 176 variation sites, 51 parsimony-informative sites and 125 singleton sites were identified. There were 40 haplotypes among the 64 sequences, which suggested a high level of heteroplasmy in R. reniformis, and 17 haplotypes were found in ZJ population, 13 haplotypes in CQ population and 12 haplotypes in FJ population. The number haplotype diversity (Hd), and nucleotide diversity (π) of 3 population were 0.946 and 0.157 4, respectively. The analysis of molecular variance (AMOVA) showed that the Fst (F-statistics) of coefficient of genetic differentiation was 0.058 15 (P＜0.01), which placed these isolates into a moderate range of genetic differentiation and no obvious geographic isolation. The variation within populations was 94.18% and only 5.82% of the variation occurred among the 3 intra-species populations. In general, the variation among COII-LrRNA gene sequence of reniform nematodes in China was obvious, which indicated that reniform nematodes in China had abundant genetic diversity, and a strong ability to adapt to environmental change. This study enriches the phylogenetic information of R. reniformis, and provides the basic evidence for the inherent genetic factors of damage from reniform nematode.
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