Variability of the North Caucasian Populations of the Greenbug for Host Virulence and Discovered by Molecular Markers

Resumo

Patterns of the genetic structure dynamics of Krasnodar and Dagestan populations of the greenbug, Schizaphis graminum Rondani, in terms of host virulence and molecular markers were examined. High seasonal polymorphism of two North Caucasian insect populations in terms of virulence frequencies to sorghum accessions protected by the major resistance genes was revealed. It was demonstrated that this variability also depended on the plant resistance genes with weak phenotypic manifestation. During feeding on sorghum, the frequencies of greenbug clones virulent to barley accessions also changed. Moreover, the selection of clones on susceptible and moderately resistant sorghum accessions was differential. On the basis of pyrosequencing of a polymorphic fragment of the mitochondrial ND4 gene, 16 greenbug haplotypes were identified. The heterogeneity and difference of the North Caucasian insect populations by the ratio of the identified haplotypes was demonstrated. In the Krasnodar population of S. graminum, both aphid clone samples sampled simultaneously on the phytophage-susceptible and moderately resistant sorghum genotypes and those sampled at different vegetation periods on the same host plant were different.