A missense mutation in TaBGLU1-5D confers early heading in wheat

Heading date (HD) in wheat determines geographic adaptation, seasonal performance, and ultimately affects yield and quality. However, the genetic regulation of HD remains unclear. Here, we identified an Ethyl Methane Sulfonate (EMS)-induced wheat mutant, je0072, which headed two days earlier than the wild-type (WT) cultivar Jing411 without significant changes in yield components. Bulked segregant analysis (BSA) using an F₂ population of 618 individuals identified the early-heading locus to the long arm of chromosome 5D. Genetic fine mapping further narrowed the locus to a 460-kb interval containing 10 high-confidence genes based on the Chinese Spring v2.1 reference genome. Sequence variation analysis identified a candidate gene, TaBGLU1-5D, encoding β-glycosyl hydrolase 1, which harbored a T-to-C substitution at position 31. Functional validation using independent mutants confirmed the role of TaBGLU1-5D in regulating HD. Transcriptome sequencing revealed that differentially expressed genes (DEGs) between WT and je0072 spikes at the heading stage were significantly enriched in starch and sucrose metabolism pathways. Weighted Gene Co-expression Network Analysis (WGCNA) further identified MADS-box transcription factor TaMADS26 as a regulatory hub associated with TaBGLU1-5D. We also found that TaBGLU1-5D modulates expression of key heading date-related genes, including VRN1, VRN3, and VRT2, thereby influencing HD. These results provide new insights into the genetic control of HD in wheat, and offer valuable resources for HD optimization in breeding programs.