Introgression of Agropyron cristatum genes to counteract the negative relationship between grain number and grain weight of wheat

Abstract Agropyron cristatum (2n = 4X = 28, PPPP), which harbour many high-yield and disease-resistance genes, is a promising donor for wheat improvement. Narrow genetic diversity and the trade-off between grain weight and grain number have become bottlenecks for increasing grain yield. In this study, WAT650l, a new translocation line was generated via radiation (60Co-γ rays)-based mutation induction of chromosome 6P addition line 4844-12. Cytological analysis and molecular marker analysis revealed that WAT650l was a 6PL (bin ~ 12–17)·5BS-5BL translocation line. Assessment of agronomic traits and analysis of the BC4F2 and BC5F2 populations suggested that the 6PL terminal chromosome segment in WAT650l resulted in increased flag leaf length, plant height (PH), spikelet number per spike (SNS), kernel number per spikelet (KNS), grain number per spike (GNS) (average increased by 14.07 grains) and thousand-grain weight (TGW) (average increased by 4.31 g) during the growing seasons of 2020–2021 and 2021–2022. Additionally, the increased GNS locus and high-TGW locus of WAT650l were mapped to 6PL (16–17) and 6PL (12–13), respectively, by genetic population analysis of three translocation lines. In summary, by using high-yield genes of A. cristatum and overcoming the negative relationship between GNS and TGW associated with wheat breeding, we provide a valuable germplasm resource for broadening the genetic base of wheat.