An efficient plant regeneration system is essential for genetic transformation and genome editing in crops. However, regeneration efficiency in major crops such as wheat exhibits strong genotype dependence. Model cultivars commonly used for transformation, such as Fielder, display high regeneration efficiency. In contrast, elite cultivars widely used in agricultural production, such as Jimai22 and Aikang58, are often recalcitrant to regeneration. This genotype dependence limits the genetic improvement of important agronomic varieties.

A research group led by XIAO Jun from the Institute of Genetics and Developmental Biology (IGDB) of the Chinese Academy of Sciences has uncovered the molecular basis underlying these differences and identified key regulatory factors that can significantly enhance regeneration efficiency in wheat cultivars.

In this study, the researchers compared the gene expression profiles, chromatin accessibility dynamics, and transcriptional regulatory networks (TRNs) in Fielder (regenerable) and Jimai22 (recalcitrant). They found that from DAI3 to DAI6, Fielder exhibits pronounced chromatin accessibility remodeling and transcriptional reprogramming, activating genes involved in auxin signaling and meristem development.

In contrast, Jimai22 displays limited transcriptional activation, with induced genes mainly associated with stress-response pathways. Comparative TRN analysis further revealed that Fielder has a more complex and regeneration-focused regulatory network.

The researchers further identified TaSCR, a Fielder-specific core transcription factor, as a central regulator linking auxin signaling to meristem-related genes expression. Auxin indirectly activates TaSCR through TaARF22 and TaGATA15, after which TaSCR directly induces downstream genes such as TaLBD17 and TaWOX5, thereby promoting cell fate transition.

Functional assays demonstrated that overexpression of TaSCR or TaLBD17 significantly improves callus induction, differentiation, and transformation efficiency in both Fielder and recalcitrant cultivars (Jimai22, Aikang58, and Kenong199). Notably, TaSCR overexpression did not cause obvious negative effects on seed development.

This study clarifies the molecular mechanisms underlying regeneration efficiency differences among wheat genotypes and identifying key regulators of wheat regeneration. The results provide insights to overcome current bottlenecks in crop genetic transformation.