The Histone Deacetylase <i>SlHDT1</i> Is Positively Involved in Response to Temperature Stress and Waterlogging Stress in Tomato ( <i>Solanum lycopersicum</i> )

ABSTRACT Plants are often subjected to various abiotic stresses in the natural environment, seriously influencing the plant growth and development and even leading to the death, but the potential mechanisms remain unknown. In this study, we investigated the role of SlHDT1 in response to abiotic stresses such as low temperature, high temperature and waterlogging. Silencing of SlHDT1 in tomato resulted in reduced tolerance to low temperature stress, high temperature stress and waterlogging stress in SlHDT1 ‐RNAi transgenic plants. Compared with wild‐type tomato (WT) plants, the transgenic lines exhibited more severe leaf wilting under low temperature, smaller leaf angles under high temperature and accelerated chlorophyll degradation under waterlogging. Consistent with these morphological changes, lower survival rate, chlorophyll content, proline content, CAT activity and ABA concentration and higher malondialdehyde (MDA) content and the level of acetylated histone H3 were exhibited in SlHDT1 ‐RNAi lines. Moreover, the transcript accumulation of abiotic stress‐related genes were analysed and confirmed by RNA‐seq and qRT‐PCR, successively. Varying degree of upregulated or downregulated of these abiotic stress‐related genes suggesting that SlHDT1 involves in the response to abiotic stresses such as low temperature stress, high temperature stress and waterlogging stress through regulating the expression of stress‐related genes. These findings suggest that SlHDT1 modulates stress tolerance by regulating stress‐responsive gene expression. In summary, the results demonstrate that SlHDT1 plays a critical role in positively regulating tolerance to low temperature, high temperature and waterlogging stresses through multiple hormone pathways. This discovery provides insights for developing crops with enhanced abiotic stress resilience in natural environment.