SES1 positively regulates heat stress resistance in Arabidopsis.

Heat stress significantly disturbs the protein folding and processing capability in plants. Molecular chaperones are vital players in unfolded/misfolded protein assembly and abiotic stress tolerance. Here, we reported SES1, which encodes an endoplasmic reticulum (ER) localized molecular chaperone, is required for Arabidopsis heat tolerance. SES1 is obviously induced by heat treatment and ses1 mutants are hypersensitive to heat stress. The unfolded protein response genes were up-regulated, while cytosolic protein response genes were down-regulated in ses1 after heat stress. Furthermore, ER stress sensor basic leucine zipper 28 (bZIP28) acts as the upstream transcriptional activator of SES1 by binding to its promoter region. These results provide new insights into heat stress responses and ER stress, and shed lights on the mechanism of SES1 in modulating heat resistance.