Characterization of the DREBA4-Type Transcription Factor (SlDREBA4), Which Contributes to Heat Tolerance in Tomatoes.

Lianzhen Mao,Zhengan Yang,Haishan Zhu,Minghua Deng,Yanling Yue,Shurui Jiang,Kai Zhao

doi:10.3389/fpls.2020.554520

Abstract

Dehydration-responsive element binding (DREB) transcription factors play crucial regulatory roles in abiotic stress. The only DREB transcription factor in tomato (Solanum lycopersicum), SlDREBA4 (Accession No. MN197531), which was determined to be a DREBA4 subfamily member, was isolated from cv. Microtom using high-temperature-induced digital gene expression (DGE) profiling technology. The constitutive expression of SlDREBA4 was detected in different tissues of Microtom plants. In addition to responding to high temperature, SlDREBA4 was up-regulated after exposure to abscisic acid (ABA), cold, drought and high-salt conditions. Transgenic overexpression and silencing systems revealed that SlDREBA4 could alter the resistance of transgenic Microtom plants to heat stress by altering the content of osmolytes and stress hormones, and the activities of antioxidant enzymes at the physiologic level. Moreover, SlDREBA4 regulated the downstream gene expression of many heat shock proteins (Hsp), as well as calcium-binding protein enriched in the pathways of protein processing in endoplasmic reticulum (ko04141) and plant-pathogen interaction (ko04626) at the molecular level. SlDREBA4 also induces the expression of biosynthesis genes in jasmonic acid (JA), salicylic acid (SA), and ethylene (ETH), and specifically binds to the DRE elements (core sequence, A/GCCGAC) of the Hsp genes downstream from SlDREBA4. This study provides new genetic resources and rationales for tomato heat-tolerance breeding and the heat-related regulatory mechanisms of DREBs.

Highlights

Dehydration-responsive element binding (DREB) proteins belong to the plant-specific APETALA2/ethylene-responsive element binding factor (AP2/ERF) family of transcription factors
The 30 leaves of the control (MicrotomCK) and heat-treated (Microtom-HS) groups were mixed to form two independent materials for DGE profiling, which was performed by the Beijing Genomics Institution (BGI)
DGE profiling successfully selected 2,820 differentiallyexpressed genes (DEGs) responding to heat, including 1,107 up-regulated genes and 1,713 downregulated genes, which were listed in an excel

Summary

Introduction

Dehydration-responsive element binding (DREB) proteins belong to the plant-specific APETALA2/ethylene-responsive element binding factor (AP2/ERF) family of transcription factors. DREBs can be induced by abiotic stresses, including drought, heat, cold, and high salt levels, and their overexpression in transgenic plants increases resistance to these stresses (Wu et al, 2017; Hu et al, 2018; Huang et al, 2018). The response patterns of DREBA1 subfamilies are mainly correlated with responses to abiotic stresses, such as cold, high salt, drought and heavy metals, and biotic stresses, such as pathogenic bacteria. DREBA2 subfamily transcription factors require posttranslational modifications to activate the downstream functional genes and increase resistance to heat and other stresses (Sakuma et al, 2006; Wu et al, 2018). The stress-response mechanisms and functions of most transcription factors in the two subfamilies, DREBA5 and DREBA6, are similar to those of the DREBA1 subfamily (Huang and Liu, 2006; Tsutsui et al, 2009; Hu et al, 2018)

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Conclusion