摘要Integration of light signaling and diverse abiotic stress responses contribute to plant survival in a changing environment. Some reports have in-dicated that light signals contribute a plant's ability to deal with heat, cold, and stress. However, the molecular link between light signaling and the salt-response pathways remains unclear. We demon-strate here that increasing light intensity elevates the salt stress tolerance of plants. Depletion of HY5, a key component of light signaling, causes Arabidopsis thaliana to become salinity sensitive. Interestingly, the small heat shock protein (sHsp) family genes are upregulated in hy5-215 mutant plants, and HsfA2 is commonly involved in the regulation of these sHsps. We found that HY5 directly binds to the G-box motifs in the HsfA2 promoter, with the cooperation of HISTONE DEACETYLASE 9 (HDA9), to repress its expression. Furthermore, the accumulation of HDA9 and the interaction between HY5 and HDA9 are sig-nificantly enhanced by salt stress. On the contrary, high temperature triggers HY5 and HDA9 degra-dation, which leads to dissociation of HY5-HDA9 from the HsfA2 promoter, thereby reducing salt tolerance. Under salt and heat stress conditions, fine tuning of protein accumulation and an inter-action between HY5 and HDA9 regulate HsfA2 ex-pression. This implies that HY5, HDA9, and HsfA2 play important roles in the integration of light sig-naling with salt stress and heat shock response.