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Seed dormancy is agronomically important trait that associates with plant survival and seed production. Wild species present long dormancy to protect their seeds from unfavourable climate conditions until the next growing season. In contrast, shortened dormancy extends crop adaptability and promotes crop rotation in agriculture. However, the shortened dormancy brought about the risk of preharvest sprouting (PHS) on cereal crops in temperate and subtropical regions. Recently, two major quantitative genetic loci Qsd1 and Qsd2 that control the seed dormancy in barley have been cloned. In this study, two kompetitive allele‐specific PCR (KASP) markers were developed and applied in a genotypic survey among 859 accessions of cultivated barley. Long‐dormancy‐associated alleles at both loci were over‐represented within East Asian accessions. Both Qsd1 and Qsd2 had significant genetic effects on seed dormancy variations in cultivated barley. Thus, the two KASP markers could be applied in selecting favourable alleles in breeding practice to optimize the seed dormancy duration. [ABSTRACT FROM AUTHOR]

Common wheat has three sets of sub-genomes, making mutations difficult to observe, especially for traits controlled by recessive genes. Here, we produced hexaploid wheat lines with loss of function of homeoalleles of Qsd1 , which controls seed dormancy in barley, by Agrobacterium -mediated CRISPR/Cas9. Of the eight transformed wheat events produced, three independent events carrying multiple mutations in wheat Qsd1 homeoalleles were obtained. Notably, one line had mutations in every homeoallele. We crossed this plant with wild-type cultivar Fielder to generate a transgene-free triple-recessive mutant, as revealed by Mendelian segregation. The mutant showed a significantly longer seed dormancy period than wild-type, which may result in reduced pre-harvest sprouting of grains on spikes. PCR, southern blotting, and whole-genome shotgun sequencing revealed that this segregant lacked transgenes in its genomic sequence. This technique serves as a model for trait improvement in wheat, particularly for genetically recessive traits, based on locus information from diploid barley. • Genome editing via Agrobacterium -delivered CRISPR/Cas9 was performed in wheat. • A triple-knockout mutation of TaQsd1 was successfully generated. • Orthologous genes of barley Qsd1 regulate seed dormancy levels in wheat. • A transgene-free null-segregant was identified by PCR and whole-genome sequencing. Using Agrobacterium -delivered CRISPR/Cas9, Abe et al. developed a loss-of-function triple mutation of Qsd1 , which controls seed dormancy in barley, resulting in longer seed dormancy in wheat. This serves as a model technique for the improvement of wheat traits, particularly genetically recessive traits, based on locus information for diploid barley. [ABSTRACT FROM AUTHOR]