| Myzus persicae is the most important pest in tobacco-growing areas. It can cause serious damage by reducing yield and quality of tobacco and it can transmit a variety of plant virus. Given the characteristics of biology and ecology of M. persicae, it has been caused widespread attention. M. persicae may produce certain population differentiation after a long-term evolutionary, so relying solely on traditional taxonomic methods have been difficult to make the identification of different M. persicae populations. In order to accurately grasp and predict the occurrence regularity and dynamic of M. persicae, we combine morphological and molecular biological methods including the morphological characteristics, the microsatellite markers, mtDNA and Buchnera symbiotic bacteria sequence to explore genetic diversity and population differentiation. The main findings are as follows:(1) In order to evaluate the morphological variations of M. persicae populations from eighteen geographical areas in China, such morphological characters as body length, body width and femur length, and Q value of M. persicae were measured and analyzed using ANOVA and Mantel test based on the relationship between the Euclidean distance and the geographical distance or altitude. The ratios of every morphological character to body length were used to carry out hierarchical cluster analysis (HCA) and principal component analysis (PCA). The results showed that there were significant differences in morphometrics among certain geographical populations. The results of HCA and PCA indicated that among the18geographical populations, the biggest difference existed between the population from Zhenfeng of Guizhou province and other populations, while the least differences were observed among the populations from Nanniwan of Shaanxi province, Cili of Hunan province, Qiaocheng of Anhui province and Wulong of Chongqing city; the differences among the other populations were between the both. The Mantel Test revealed that there was no significant correlation between the Euclidean distance and the geographical distance or altitude.(2) The genetic variability of54populations of M. persicae from different places were analyzed using five microsatellite loci. A average of7alleles were detected by using five microsatellite loci, the effective number of alleles were among1.5-6.6, the average polymorphic information content was0.652and the Shannon’s diversity index was among0.715-1.999. The mean observed heterozygosity of54populations was0.735, the mean expected heterozygosity was0.464, with the genetic identity of0.1011-1. The mean fixation index and the mean gene flow was0.34and0.50, respectively. Lower expected heterozygosity and fixation index showed a high genetic differentiation. The populations of M. persicae from54areas were classified into seven groups according to genetic distance. Mantel test revealed there was no significant correlation between genetic distance and geographical distance or altitude. The5microsatellite loci selected were of high polymorphism. The fixation index and the gene flow revealed that there had a high genetic variability among populations of M. persicae. Additionally, the low gene flow could lead to genetic drift easily. The genetic diversity of M. persicae populations was relation to reproductive modes and ecological factors. (3) The Buchnera trpB genes in36geographical populations of M. persicae were amplification using the trpB universal primers. The result showed all sequences were385bp, and parts of the sequences were the same while others had mutation or deletion of single bases. The results showed that there were small different among Buchnera in36geographical populations of M. persicae.In this study, the mitochondrial CO Ⅰ-Ⅱ gene of different populations of M. persicae did not appear different, but the results from morphological analysis, microsatellite markers and symbiotic bacteria Buchnera trpB gene sequencing have shown there were differences within and among M. persicae populations. |
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