Introducing chromosome 1Ns from Leymus mollis improves grain protein content of recipient wheat.

key messageReplacing wheat chromosome 1D with its relative Leymus mollis chromosome 1Ns facilitates the incorporation of storage protein subunits, thereby improving the grain quality of wheat. Wild relatives of wheat serve as valuable gene pools for enhancing genetic diversity of wheat. Leymus mollis Trin. (L. mollis, 2n = 4x = 28, NsNsXmXm) exhibits multiple advantageous traits including disease resistance, stress tolerance, and high grain quality, rendering it a promising genetic resource for wheat improvement via distant hybridization. In this study, 82 wheat-L. mollis derivatives were assessed for grain quality. The superior line WM24 was further analyzed using biochemical, molecular, and cytogenetic methods. Seed storage protein electrophoresis revealed that improved quality of WM24 stems from introducing high-molecular-weight glutenin subunits and gliadins from L. mollis. Genomic in situ hybridization (GISH) confirmed that the chromosomal composition of WM24 was 2n = 42 = 21 II, including a pair of homologous chromosomes from Ns genome of L. mollis. The combination of molecular markers and sequential FISH-GISH indicated that WM24 carries two 1Ns chromosomes substituting for wheat chromosome 1D. SNP array analysis showed predominantly deletion (NA) genotypes of SNPs at 1D loci, corroborating the substitution event. These findings demonstrate that the introducing of L. mollis chromatin positively influences wheat grain quality. WM24 is a wheat-L. mollis 1Ns (1D) substitution line with higher protein content and sedimentation value due to altered storage protein profiles, resulting in enhanced quality traits. The development of these derivatives provides valuable germplasms for wheat quality breeding and exploration of novel exogenous quality-related genes.