Chromatin accessibility and TaSCR-TaLBD17 circuitry shape genotypic regeneration capacity in wheat

Genotype-dependent regeneration efficiency remains a major obstacle in wheat transformation, limiting its use in elite but recalcitrant cultivars. To elucidate the molecular basis of regeneration divergence, we compare transcriptomic profiles, chromatin accessibility dynamics, and transcriptional regulatory networks (TRNs) between the regenerable variety Fielder and the recalcitrant variety JiMai22 (JM22). Fielder displays dynamic transcriptional reprogramming and chromatin remodeling between 3 and 6 days after induction, activating morphogenic regulators such as TaSCR, TaWOX5, and TaLBD17. In contrast, JM22 shows limited chromatin changes and transcriptional stagnation, primarily inducing stress-responsive pathways. TRN analysis reveals a more complex, regeneration-focused network in Fielder, enriched with AP2, Dof, and GRAS transcription factor families. Among these, TaSCR is identified as a key regulator. Functional assays demonstrate that the TaSCR-TaLBD17 regulatory cascade improves transformation efficiency across diverse wheat genotypes. These findings provide a molecular framework to overcome transformation barriers in recalcitrant cultivars.