Characterization of a greenbug resistance gene in a wheat breeding line BW 49921

Abstract

Greenbug [Schizaphis graminum (Rondani)] is a major wheat (Triticum aestivum L.) pest that causes significant yield losses worldwide. Use of plant resistance is an effective and environmentally friendly strategy to manage greenbug. BW 49921 is a spring wheat breeding line showing resistance to major US greenbug biotypes. Genetic analysis of an F_2:3 population from the cross BW 49921 × Breakthrough revealed a single dominant gene conditioning greenbug resistance in BW 49921, and selective genotyping identified a genomic region associated with the greenbug resistance in chromosome arm 7DL. Ten single nucleotide polymorphisms (SNPs) in the target genomic region were converted to kompetitive allele-specific PCR (KASP) markers to genotype the entire F₂ population. Linkage analysis using F_2:3 phenotypic data delimited the greenbug resistance gene in BW 49921, designated Gb49921, to a 0.5-Mb interval between Stars-KASP419 (598.8 Mb) and Stars-KASP1061 (599.3 Mb). Gb49921 was 1.0 cM distal to Stars-KASP419 and 0.6 cM proximal to Stars-KASP1061. Allelism tests indicated that Gb49921 is not allelic to either Gb3 or Gb8. Gb49921 confers high resistance to greenbug biotypes C, E, H, I, and K and moderate resistance to TX1. The KASP markers developed in this study can be used for marker-assisted selection of Gb49921 in wheat breeding programs.