Molecular diversity assessment of rice genotypes for brown planthopper resistance using microsatellite markers

Abstract

The brown planthopper Nilaparvatalugens (Stål) is a major insect pest that is primarily present in Asia causing a significant impact on rice crop. Seventy-three rice genotypes were evaluated for molecular diversity based on known BPH resistance loci. A total number of 108 alleles were detected by 39 polymorphic markers with an average of 2.37 alleles per locus. The allele frequency which is useful in estimating the frequency of alleles, ranged from 0.054 to 0.9726, while the expected heterozygosity varied between 0.054 (RM494) and 0.688 (RM231) with an average of 0.431.The Polymorphic Information Content (PIC) values provided an estimation of the marker’s discriminating power by ranged from 0.066 (RM496) to 0.621 (RM231) suggesting moderate level of polymorphism for the selected BPH specific SSR markers among the germplasm lines. Accounting the major allele frequency, heterozygosity and PIC content, the marker RM231 associated with QBph3.1 and regarded as the most informative one along with RM19291, RM335, RM469, RM518, RM8213, RM228, RH078 and RM589 for dissecting the molecular diversity of germplasm lines with respect to BPH resistance. Based on the marker data, the genotypes were classified into seven clusters that distinguished the lines clustering as resistant and susceptible separately. The information about the genetic diversity of these lines will be extremely useful for proper selection of parents related to BPH reaction, especially for gene mapping and for marker assisted selection.