Improves Plant Thermotolerance via Regulating the Expression of Stress- and Antioxidant-Related Genes.

Heat shock transcription factor (Hsf) plays an important role in regulating plant thermotolerance. The function and regulatory mechanism of in heat stress tolerance of pepper have not been reported yet. In this study, phylogenetic tree and sequence analyses confirmed that is a class A Hsf. harbored transcriptional function and predicted the aromatic, hydrophobic, and acidic (AHA) motif mediated function of as a transcription activator. Subcellular localization assay showed that protein is localized in the nucleus. The was transcriptionally up-regulated at high temperatures and its expression in the thermotolerant pepper line R9 was more sensitive than that in thermosensitive pepper line B6. The function of under heat stress was characterized in -silenced pepper plants and -overexpression plants. Silencing of the reduced the thermotolerance of the pepper, while -overexpression plants exhibited an increased insensitivity to high temperatures. Moreover, the maintained the HO dynamic balance under heat stress and increased the expression of , (heat shock protein), and antioxidant gene (glutathione S-transferase class tau 5) in transgenic lines. Our findings clearly indicate that improved the plant thermotolerance via regulating the expression of stress- and antioxidant-related genes.