Barley (Hordeum vulgare L.) HvDEP1 alleles and their effect on agronomic and physical grain traits

The Dense and erect particle 1 (HvDEP1) gene, located on chromosome 5H in barley (Hordeum vulgare L.), encodes a heterotrimeric G-protein {gamma}-subunit that regulates grain size and stem elongation. Multiple alleles of HvDEP1 have been identified, including the widely utilized semi-dwarf allele HvDEP1.GP, caused by an insertion mutation, and a recently discovered variant, HvDEP1.V, characterized by two deletions in the putative cis-regulatory region. In this study, we evaluated the phenotypic effects of HvDEP1.V relative to HvDEP1.GP and the wild-type allele (HvDEP1.WT) using two BC{square}F{square} populations across multi-environment field trials spanning two locations and three years. HvDEP1.V was associated with plants that were 5-14.6 cm taller, had 3-6.7 higher lodging score, and increased head loss compared to HvDEP1.GP. HvDEP1.V showed comparable agronomic attributes to HvDEP1.WT. Substituting HvDEP1.V for HvDEP1.GP significantly increased all physical grain attributes, including grain width (1.44-4.24% in three out of five environments), grain length (4.88-8.69 %), grain area (6.45-11.06%) and thousand-grain weight (6.75-13.8%). Out of five environments, compared to HvDEP1.WT, HvDEP1.V was associated with wider grain in three environments, shorter grain in four environments, and increased grain roundness in four environments. These findings link allelic variation of the HvDEP1 gene to key agronomic and physical grain traits and demonstrate the functional consequences of HvDEP1.V in diverse genetic backgrounds and field conditions, providing valuable insights for barley improvement. Key messageBy evaluating agronomic performance and physical grain traits in two genetically distinct barley populations across multiple environments, we reveal strong environment- and background-dependent effects of HvDEP1 alleles.