Editing the conserved IPA1 – TB1 regulatory module reshapes plant architecture and enhances tillering in wheat

Plant architecture is a major determinant of yield potential in cereal crops, where tiller number directly influences spike production and grain yield. The transcriptional regulators Ideal Plant Architecture 1 ( IPA1 ) and Teosinte Branched1 (TB1) constitute a conserved genetic module controlling axillary bud activity and branching in grasses; however, their functional contribution to wheat architecture remains largely unexplored. Here, we employed CRISPR/Cas9-mediated genome editing to investigate the roles of TaIPA1 and TaTB1 in regulating tillering in hexaploid wheat ( Triticum aestivum L.). Comparative genomic analysis identified conserved IPA1 orthologs across the wheat A, B, and D sub-genomes, with strong conservation of the SQUAMOSA-binding protein domain. Sequencing analysis confirmed targeted mutations, including nucleotide substitutions and insertions that generated frameshift mutations and premature stop codons. Genome-edited lines exhibited enhanced tillering compared with wild-type plants. Several TaIPA1 mutant lines produced up to two-fold higher tiller numbers, while TaTB1 knockout lines showed earlier tiller initiation and ∼50% increased tillering. Notably, enhanced tillering was associated with increased grain weight without affecting spikelet number per spike. Together, these results demonstrate that the conserved TaIPA1–TaTB1 regulatory module plays a pivotal role in shaping wheat plant architecture. Targeted manipulation of this pathway using CRISPR/Cas9 provides a promising strategy for optimizing tillering and developing high-yielding wheat ideotypes.