A small heat shock protein (SlHSP17.3) in tomato plays a positive role in salt stress

Small heat shock proteins (sHSPs) are molecular chaperones that are widely present in plants and play a vital role in the response of plants to various environmental stimuli. This study employed transgenic <i>Arabidopsis</i> to investigate the impact of the new tomato (<i>Solanum lycopersicum</i>) sHSP protein (SlHSP17.3) on salt stress tolerance. Transient conversion analysis of <i>Arabidopsis</i> protoplasts revealed that SlHSP17.3 localized to the cytoplasm. Furthermore, as suggested by expression analysis, salt stress stimulated <i>SlHSP17.3</i> expression, suggesting that SlHSP17.3 is involved in the salt stress response of plants. <i>SlHSP17.3</i>-overexpressing plants presented greater germination rates, fresh weights, chlorophyll contents, and Fv/Fm ratios, as well as longer root lengths, lower reactive oxygen species (ROS) levels, and lighter cell membrane injury under salt stress. Furthermore, certain stress-related genes (<i>AtCOR15</i>, <i>AtDREB1B</i>, and <i>AtHSFA2</i>) were up-regulated in salt-stressed transgenic plants. Overall, <i>SlHSP17.3</i> overexpression improved the salt stress resistance of transgenic plants, mainly through increasing <i>AtCOR15</i>, <i>AtDREB1B</i>, and <i>AtHSFA2</i> expression.