Assessment of wheat variety stability using SSR markers

Abstract

In International Union for the Protection of New Varieties of Plants member countries, assessment of wheat variety stability is a statutory requirement before new varieties are registered and plant breeders’ rights are granted. However, it is impossible to test the stability of varieties accurately and quickly, or to assess the stability of a large number of varieties in a short time based on the morphological traits defined by the national standard. The objective of this study was to establish method and procedure of wheat variety stability assessment using SSR markers as a replacement for morphological observations. In preliminary study, the methods to identify non-homozygous SSR loci and calculate the homozygous SSR loci ratio (SSR–HLR) of wheat varieties were established. On this basis, the genotypes at 347 molecular markers loci of 20 advanced lines demonstrated that SSR–HLRs were 84.7–94.8 % in the F4 lines, 96.1–99.4 % in the F5 lines, and ≥98 % in the F6 lines, respectively. Eighty of 347 markers with good polymorphism, stable PCR amplification, and high resolving power of genotyping were recommended to detect SSR–HLR for 633 wheat regional trial varieties. Comparing morphological observation, the varieties with SSR–HLR >95 % were deemed stable; the varieties with SSR–HLR <91 % were deemed unstable; the varieties with SSR–HLR ranging from 91 to 95 % were required field identification for stability assessment. Based on the relationship between the homozygous SSR loci ratio and wheat variety stability, procedures for the assessment of wheat variety stability using SSR markers were established.