Overexpression of BnaXTH22 Improving Resistance to Aluminum Toxicity in Rapeseed (Brassica napus L.)

The cell wall is the primary cellular structure that encounters and perceives Al³⁺, acting as the first line of defense against aluminum (Al) toxicity. Xyloglucan endotransglucosylase/hydrolase (XTH) plays a pivotal role in mediating cell wall remodeling, a critical mechanism for Al toxicity tolerance. In our previous studies, the candidate gene BnaXTH22 was identified through GWAS and RNA-seq analyses. Under Al toxicity stress, overexpression lines (OEs) exhibited a significant increase in relative elongation of taproots (9.44%–13.32%) and total root length (8.15%–12.89%) compared to the wild type (WT). Following Al treatment, OEs displayed reduced MDA content and lower relative electrical conductivity, alongside significantly higher root activity than WT. Transcriptomic analysis revealed that differentially expressed genes in OE plants under Al toxicity were predominantly enriched in stress-related biological processes, including phenylpropanoid metabolism, fatty acid biosynthesis, and lignin biosynthesis. These findings suggested that BnaXTH22 overexpression enhances Al toxicity tolerance in rapeseed, potentially by modulating cell wall synthesis to bolster plant resistance.