Cahsfald improves plant thermotolerance via regulating the expression of stress-and antioxidant-related genes

Abstract

Heat shock transcription factor (Hsf) plays an important role in regulating plant thermotolerance. The function and regulatory mechanism of CaHsfAld in heat stress tolerance of pepper have not been reported yet. In this study, phylogenetic tree and sequence analyses confirmed that CaHsfAld is a class A Hsf. CaHsfAld harbored transcriptional function and predicted the aromatic, hydrophobic, and acidic (AHA) motif mediated function of CaHsfAld as a transcription activator. Subcellular localization assay showed that CaHsfAld protein is localized in the nucleus. The CaHsfAld 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 CaHsfAld under heat stress was characterized in CaHsfAld-silenced pepper plants and CaHsfAld-overexpression Arabidopsis plants. Silencing of the CaHsfAld reduced the thermotolerance of the pepper, while CaHsfAld-overexpression Arabidopsis plants exhibited an increased insensitivity to high temperatures. Moreover, the CaHsfAld maintained the H2O2 dynamic balance under heat stress and increased the expression of Hsfs, Hsps (heat shock protein), and antioxidant gene AtGSTU5 (glutathione S-transferase class tau 5) in transgenic lines. Our findings clearly indicate that CaHsfAld improved the plant thermotolerance via regulating the expression of stress- and antioxidant-related genes.