Hvpr1 Overexpression Significantly Enhances Thousand-Grain Weight in Barley

Abstract

Grain size critically impacts crop yield and quality. This study compared two qingke varieties with contrasting grain sizes using dynamic phenotyping, transcriptomics,  and weighted gene co-expression network analysis (WGCNA). Key findings showed rapid grain expansion at 16-28 DAF, while peak differential gene expression occurred earlier at 13 DAF, indicating transcriptional changes precede morphological changes. WGCNA identified a brown module enriched with MAPK pathway genes linked to grain dimensions and weight. Functional analysis of HvPR1 from this pathway revealed its novel role in grain development—overexpression in barley increased thousand-grain weight but reduced grain length, likely by modulating endosperm architecture and cell wall composition. These insights offer genetic resources for precision breeding in barley and related cereals, highlighting the importance of temporal gene expression in grain morphology and yield.

Keywords: grain size, WGCNA, MAPK pathway, HvPR1