Genomic characterization of the Hordeum vulgare DEP1 (HvDEP1) gene and its diversity in a collection of barley accessions

Grain yield potential in cereals results from the contributions of three main components: inflorescence number per plant, grain number per inflorescence and mean grain weight. In rice, the Dense and erect panicle (DEP1) gene affects three important quantitative traits of the inflorescence and DEP1 homologs have been reported in barley and wheat. In this work, we have performed a detailed characterization of the barley DEP1 (HvDEP1) gene. We obtained a full-length sequence of its transcript, examined its expression in various tissues, genetically mapped it to chromosome 5H and measured its nucleotide diversity in a collection of barley cultivars from Canada. This gene has an exceptionally long 5′ UTR (297 bp) that contains an upstream open reading frame (uORF) coding for a predicted peptide of 70 amino acids. A similarly long 5′ UTR containing a putative uORF was found in all six grass species that we examined. Although HvDEP1 transcripts could be detected in all tissues tested, it was highest in meristematic tissues. In a collection of 167 barley cultivars, a low level of polymorphism was observed (π = 0.001) and the 37 SNPs/indels detected, none of which result in changes in the amino acid sequence of the HvDEP1 protein, defined 8 haplotypes. Diversity was especially low among 83 six-row types, all but one of which carried the exact same haplotype. We suggest that HvDEP1 is involved in the control of cellular growth and differentiation, that the conserved uORF may play a role in its post-transcriptional regulation and that this gene has undergone a very different history of selection within the two-row and six-row Canadian elite germplasm.