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

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, <i>SlMYB306-like</i>, 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 <i>SlMYB306-like</i> was inducible by NaCl and abscisic acid (ABA) treatments. In addition, functional characterization via the overexpression of <i>SlMYB306-like</i> in <i>Arabidopsis thaliana</i> 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 <i>SlMYB306-like</i> upregulated the expression of several stress-responsive genes, including <i>AtSOD1</i>, <i>AtCAT1</i>, <i>AtEGY3</i>, <i>AtP5CS2</i>, and <i>AtRD29A</i>. 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.