CaHsfA1d Improves Plant Thermotolerance via Regulating the Expression of Stress- and Antioxidant-Related Genes

Wen-Xian Gai,Abid Khan,Xiao Ma,Yang Li,Zhen-Hui Gong,Quan-Hui Li,Jing-Jing Xiao

doi:10.3390/ijms21218374

Abstract

Heat shock transcription factor (Hsf) plays an important role in regulating plant thermotolerance. The function and regulatory mechanism of CaHsfA1d in heat stress tolerance of pepper have not been reported yet. In this study, phylogenetic tree and sequence analyses confirmed that CaHsfA1d is a class A Hsf. CaHsfA1d harbored transcriptional function and predicted the aromatic, hydrophobic, and acidic (AHA) motif mediated function of CaHsfA1d as a transcription activator. Subcellular localization assay showed that CaHsfA1d protein is localized in the nucleus. The CaHsfA1d 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 CaHsfA1d under heat stress was characterized in CaHsfA1d-silenced pepper plants and CaHsfA1d-overexpression Arabidopsis plants. Silencing of the CaHsfA1d reduced the thermotolerance of the pepper, while CaHsfA1d-overexpression Arabidopsis plants exhibited an increased insensitivity to high temperatures. Moreover, the CaHsfA1d 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 CaHsfA1d improved the plant thermotolerance via regulating the expression of stress- and antioxidant-related genes.

Highlights

Environmental factors, especially heat stress, can significantly threaten crop productivity and grain quality worldwide
Eight Heat shock transcription factor (Hsf) closely related to the CaHsfA1d protein were downloaded and one of the obtained proteins was CaHsfA1d protein numbered by XP_016554315.1 in NCBI (Figure 1B)
The alignment confirmed that the CaHsfA1d contained the typical domains of HsfA1, including a conserved DNA binding domain (DBD), a HR-A/B domain inserted by 21 amino acids, a nuclear localization signal (NLS), a nuclear export signals (NES), and an AHA motif (Figure 1C)

Summary

Introduction

Environmental factors, especially heat stress, can significantly threaten crop productivity and grain quality worldwide. Plants are constantly exposed to environmental stresses and unable to escape from high environmental temperature. Plants have formed a series of adaptive physiological mechanisms and molecular regulatory networks to respond to these rising temperatures and improve their own resistance in the long evolutionary process. It has become clear that early perception and regulatory networks of heat shock signal in plants are mainly mediated by transcriptional factors [3]. Heat shock transcription factors (Hsfs) act as main regulatory components and key terminal factors of the heat shock response during the signal transduction pathway of heat stress, and can regulate the expression of downstream target genes related to defense against environmental stresses [4,5,6,7]

Methods

Results

Conclusion