# BnaMYB73, a Brassica napus L. R2R3-MYB Transcription Factor, Enhances Plant Salt and Osmotic Stress Tolerance

## TL;DR

This study identifies BnaMYB73, a gene in rapeseed, that helps plants tolerate salt and osmotic stress without affecting normal growth.

## Contribution

BnaMYB73 is newly characterized as a stress-responsive R2R3-MYB transcription factor in Brassica napus.

## Key findings

- BnaMYB73 expression increases under salt and osmotic stress.
- Transgenic Arabidopsis with BnaMYB73 showed higher stress tolerance and improved physiological responses.
- Stress-related genes like AtRD29B and AtSOS1 were upregulated in BnaMYB73-expressing plants.

## Abstract

MYB transcription factors (TFs) are crucial for plant growth, development, and response to abiotic stress. However, their exact functions in abiotic stress responses in rapeseed remain largely unexplored. In this study, we identified and characterized BnaMYB73, a member of the R2R3-MYB subfamily, and investigated its role in abiotic stress tolerance. The transcription level of BnaMYB73 was significantly upregulated in response to salt and osmotic stress. Transgenic Arabidopsis thaliana lines expressing BnaMYB73 displayed significantly enhanced tolerance to salt and osmotic stress, while showing no phenotypic differences in growth compared with wild-type (WT) plants under normal conditions. Physiological analyses revealed that the BnaMYB73-expressing plants accumulated higher proline levels, exhibited elevated superoxide dismutase (SOD) and peroxidase (POD) activities, and reduced malondialdehyde (MDA) content under stress conditions. Moreover, the BnaMYB73-expressing plants significantly upregulated key stress-responsive genes, including AtRD29B, AtDREB2A, AtRAB18, AtP5CS1, AtSOS1 and AtCAT1. Collectively, these findings establish BnaMYB73 functions as a stress-responsive transcription factor that enhances abiotic stress tolerance and provide a promising target for breeding stress-resilient rapeseed cultivars.