SYNTHETIC HEXAPLOID WHEATS AS A NOVEL SOURCE OF GENETIC DIVERSITY AND RESISTANCE AGAINST YELLOW RUST

Abstract

Special subsets of synthetic hexaploid wheats (SHWs) have been formed and one such subset is “Elite ІІ” comprising of 33 SH entries. The subset was screened against yellow rust having virulence for Yr1, Yr4, Yr6, Yr7, Yr8, Yr9, Yr12, Yr17, Yr18, Yr26, Yr27, YrSp, YrSu, YrSk and YrA; collected from diverse wheat growing areas of Pakistan. Fifteen genotypes were found resistant at seedling stage by exhibiting infection type 2-4, indicating the presence of major resistant genes. Adult plant screening under field conditions showed 8 genotypes resistant, three moderately resistant and 4 susceptible. Six RAPD markers of 10-mer arbitrary sequences were applied for genetic diversity analysis of these 15 genotypes. Fifty eight amplicons were generated by 4 primers. Total 83.33% polymorphism was computed among 15 lines. Dendrogram showed 15 genotypes divided into two distinct clusters. The coefficients are in the range of 38.89% to 100% on similarity matrix. Genotypes Elite ІІ-16 and 31 were most polymorphic with 38.89% similarity. Genetic diversity and resistance identified can be exploited in wheat breeding for yield and durable resistance against yellow rust, using limited and genetically diverse SHWs for commercial bread wheat improvement.