Abstract:

Objective: This study aims to explore the genetic diversity, genetic differentiation, and phylogenetic relationships of Paratrioza sinica populations in northwest China, so as to provide molecular biological theoretical basis for the regional occurrence patterns of P. sinica and the formulation of prevention and control strategies. Method: In this study, 512 samples of P. sinica were collected from 18 different geographical populations in northwest China from June to August 2023. The mtDNA COI gene was amplified with PCR and sequenced, and the mtDNA COI gene sequence variation, phylogenetic and genetic differentiation were analyzed by using MEGA7.0, Dna SP 5.0, Arlequin 3.5, and Network 10.0 software. Result: 1) The length of the amplified fragment was 474 bp, and the content of the base T, C, A, and G was 35.6%, 22.2%, 26.8%, and 15.4%, respectively. The A+T content (62.4%) was significantly higher than the G+C content (37.6%), showing a significant base bias. The nucleotide diversity was 0.002 5, and the average nucleotide difference number of k was 1.110. 2) There were 5 haplotypes detected, with the haplotype diversity of 0.512. Among them, haplotype H2 was the dominant haplotype, and appeared 344 times, accounting for 67.19% of all detected individuals. 3) The Taijima's D and Fu's Fs values of the 18 P. sinica geographic populations were 0.876 and 0.911, respectively, and both of them did not reach significant levels. 4) The population genetic differentiation index was 0.642 78, and the gene flow was 0.21. The percentage of genetic variation within populations was 35.72%, and the percentage of genetic variation between populations was 64.28%. The variation within populations was significantly smaller than that between populations (P<0.01). 5) The haplotype NJ phylogenetic tree and network mediation diagram showed that the five haplotypes were clearly clustered into 4 clusters. 6) The genetic distance among various populations ranged from 0.000 to 0.007. The UPGMA clustering results indicated that the populations from Delingha (DLH) and Golmud (GEM), as well as those from Gulang County (GLX) and Shihezi (SHZ) were significantly differentiated compared to other populations. 7) The Mantel test showed that there was a significant moderate positive correlation (r=0.675, P<0.05) between genetic distance and geographic distance among the 18 geographical populations of P. sinica. Conclusion: The 18 geographical populations of P. sinica in the northwest region exhibit low genetic diversity, with genetic variation occurring both among and within populations. The main factor contributing to the overall population variation is interpopulation variation, while intrapopulation genetic differentiation is relatively low.

Key words: Paratrioza sinica, mitochondrial DNA COI, geographical population, genetic differentiation