Genetic Diversity and Population Structure of Bursaphelenchus xylophilus in Central China Based on SNP Markers.

Hubei, Hunan and Henan Provinces are located in Central China, a region with extensive transport networks and trade. The pine wilt nematode (PWN), Bursaphelenchus xylophilus, the causative agent of pine wilt disease, is spread mainly through human activities. To further understand the genetic structure of PWN in Central China, we studied the genetic information of PWN populations in this region and compared the genetic relationship with strains from Guangdong and Jiangsu provinces. We found that the HB (Hubei) 15, HEN (Henan) 20, HN (Hunan) 07, HN08 and HN10 had significantly more SNPs and homozygotes than other strains from Central China, and their most frequent mutant genotypes also differed from other strains. The clustering results indicated that HB15, HEN 20, HN07, HN08 and HN10 were genetically distinct from other strains and closely related to Guangdong strains. We also observed significant genetic variation among strains in Henan province, suggesting that some of them might have different transmission sources than those from Hubei and Hunan provinces. Introgression analysis identified three possible pathways: (1) Guangdong to Henan; (2) Guangdong to Hunan; and (3) Jiangsu to Hubei. The results provide a basis for tracing the origin and spread of pine wood disease in China. [ABSTRACT FROM AUTHOR]