Introgression of genetic material from primary synthetic hexaploids into an Australian bread wheat (Triticum aestivum L.).

Abstract

Primary synthetic wheats, created by hybridising Triticum turgidum L. with Aegilops tauschii Coss., the evolutionary progenitors of bread wheat (Triticum aestivum L.), have shown potential value for use in Australian bread wheat breeding. This study investigated primary and derived synthetic wheats in three ways to further evaluate this value. To determine whether primary synthetic wheats could broaden genetic diversity in Australian bread wheats, genetic similarity between and among 44 primary synthetics and nine modern Australian bread wheats was investigated using Diversity Array Technology™ (DArT). Greater dissimilarity was observed between these germplasm groups than within these groups. The A and B genomes of the primary synthetics were most divergent from the genomes of the bread wheats. These primary synthetics therefore could broaden the genetic diversity in Australian bread wheats. To identify primary synthetic wheats that could improve grain yield of an Australian bread wheat in drought, grain yield and its major components (grain weight and grains per m²) were measured in 27 BC₁ synthetic-derived families of lines in five drought stressed environments in southern Australia. Fourteen families included lines with significantly (p<0.05) higher grain yield than Yitpi (recurrent bread wheat parent). These lines produced grain yields up to 12.0% higher than Yitpi in the highest yielding environments, where improved grain weights were responsible. In the lowest yielding environments, superior synthetic derivatives achieved grain yields up to 43.8% higher than Yitpi, with more grains per m² commonly responsible. Therefore, many but not all of the primary synthetics assessed could improve grain yield of an Australian bread wheat in drought. To gain an understanding of synthetic allele introgression into the genetic background of an Australian bread wheat, DArT loci were assayed in two families of synthetic backcross lines. Approximately half of the same loci assayed in each family showed synthetic allele introgression. At regions on chromosome 2A in both families, synthetic alleles were positively associated with grain weight and grain per m². It was concluded that primary and derived synthetic wheats can have broad value to bread wheat breeding in Australia.