Cellulose synthase TaCESA7 negatively regulates wheat resistance to stripe rust by reducing cell wall lignification.

Cellulose is synthesized by cellulose synthases (CESAs) in plasma membrane-localized complexes, which act as a central component of the cell wall and influence plant growth and defense responses. Puccinia striiformis f. sp. tritici (Pst) is an airborne fungus that causes stripe rust to seriously endanger wheat production. In this study, a CESA gene, TaCESA7, was identified to be significantly up-regulated during Pst infection in wheat (Triticum aestivum L.). TaCESA7 was localized on the plasma membrane in dimeric form, and the dimers interact to assemble into CESA complexes. Stable overexpression of TaCESA7 weakened the resistance of wheat to Pst. Knockdown of TaCESA7 by RNA interference (RNAi) and virus-induced gene silencing led to restricted hyphal spread, increased necrotic area, and simultaneously promotes reactive oxygen species (ROS) accumulation and the expression of pathogenesis-related (PR) genes. Transcriptome analysis of TaCESA7-RNAi plants revealed that the up-regulated genes were significantly enriched in the phenylpropanoid biosynthesis and plant-pathogen interaction pathways. Moreover, silencing TaCESA7 promoted the deposition of lignin and the expression of genes related to lignin synthesis. CRISPR-Cas9-mediated inactivation of TaCESA7 in wheat could confer broad-spectrum resistance against Pst without affecting agronomic traits. These findings provide valuable candidate gene resources and guidance for molecular breeding to improve the resistance of wheat to fungal disease.