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

## TL;DR

Overexpression of the BnaXTH22 gene improves rapeseed's resistance to aluminum toxicity by enhancing root growth and reducing stress effects.

## Contribution

The novel contribution is identifying BnaXTH22 as a key gene improving aluminum toxicity resistance in rapeseed through cell wall remodeling.

## Key findings

- Overexpression of BnaXTH22 increased taproot elongation and total root length under aluminum stress.
- Overexpression lines showed reduced MDA content and lower electrical conductivity compared to wild type.
- Transcriptomic analysis linked BnaXTH22 to stress-related processes like lignin and fatty acid biosynthesis.

## Abstract

The cell wall, acting as the first line of defense against aluminum (Al) toxicity, is the primary cellular structure that encounters and perceives Al3+. 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 the 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 a significantly higher root activity than WT. Transcriptomic analysis revealed that differentially expressed genes in OE under Al toxicity were predominantly enriched in stress-related biological processes, including phenylpropanoid metabolism, fatty acid biosynthesis, and lignin biosynthesis. These results suggest that BnaXTH22 overexpression could enhance Al toxicity tolerance in rapeseed, potentially by modulating cell wall synthesis to bolster plant resistance.