# Characterization of a Novel Tomato R2R3-MYB Transcription Factor Gene, SlMYB306-like, Conferring Salt Tolerance in Arabidopsis

## TL;DR

This study identifies a new tomato gene, SlMYB306-like, that improves salt tolerance in plants, offering a potential tool for developing crops that can grow in salty soils.

## Contribution

The paper introduces and characterizes a novel tomato R2R3-MYB transcription factor gene, SlMYB306-like, which enhances salt tolerance in Arabidopsis.

## Key findings

- SlMYB306-like overexpression in Arabidopsis increased salt tolerance through improved photosynthetic efficiency and osmotic adjustment.
- The gene upregulated stress-responsive genes like AtSOD1 and AtCAT1, enhancing ROS scavenging and reducing oxidative damage.
- SlMYB306-like is inducible by NaCl and ABA, suggesting its role in abiotic stress signaling pathways.

## Abstract

Soil salinization is a serious global issue that limits plant growth, reduces crop yields, and threatens agricultural productivity. As a result, plants have developed sophisticated adaptive strategies to improve salt tolerance for sustainable agricultural development. The MYB transcription factor family is one of the largest in plants and is integral to the regulation of physiological and biochemical processes under abiotic and biotic stresses. This study presents the first isolation and characterization of a new tomato R2R3-MYB factor, SlMYB306-like, which is shown to enhance salt tolerance by modulating both plant growth and physiological parameters such as photosynthetic efficiency, osmotic adjustment substance levels, and antioxidant enzyme activities. Mechanistically, SlMYB306-like mediated salt tolerance by upregulating key genes involved in ROS scavenging and salt stress responses. Overall, the results reveal SlMYB306-like as a critical regulator of salt tolerance, providing a valuable genetic resource for developing salt-tolerant crops and boosting yields in high-salinity soils, in turn supporting more stable food production.

Soil salinization significantly limits plant growth and agricultural productivity, with MYB transcription factors playing crucial roles in mediating plant responses to salt stress. In this study, a novel R2R3-MYB transcription factor gene, SlMYB306-like, was isolated from tomato. Phylogenetic comparison indicated that SlMYB306-like shared the highest sequence homology with potato StMYB306-like. Subcellular localization assays demonstrated nuclear localization of SlMYB306-like protein, while yeast transactivation assays confirmed its function as a transcriptional activator. Expression profiling showed that SlMYB306-like was inducible by NaCl and abscisic acid (ABA) treatments. In addition, functional characterization via the overexpression of SlMYB306-like in Arabidopsis thaliana revealed enhanced salt tolerance, evidenced by an increased maximum quantum efficiency of photosystem II (Fv/Fm) and proline levels alongside decreased accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) content under salt stress conditions. Furthermore, the overexpression of SlMYB306-like upregulated the expression of several stress-responsive genes, including AtSOD1, AtCAT1, AtEGY3, AtP5CS2, and AtRD29A. Collectively, these findings suggest that SlMYB306-like enhances salt tolerance by modulating ROS scavenging, osmotic adjustment, and ABA signaling pathways, thereby representing a promising candidate gene for the development of salt-tolerant crops.