Arabidopsis WRKY46, WRKY54 and WRKY70 Transcription Factors Are Involved in Brassinosteroid-Regulated Plant Growth and Drought Response

Abstract

Plant steroid hormones, brassinosteroids (BRs), play important roles in growth and development. BR signaling controls the activities of BRASSINOSTERIOD INSENSITIVE1-EMS-SUPPRESSOR1/BRASSINAZOLE-RESISTANT1 (BES1/BZR1) family transcription factors. Besides the role in promoting growth, BRs are also implicated in plant responses to drought stress. However, the molecular mechanisms by which BRs regulate drought response have just begun to be revealed. The functions of WRKY transcription factors in BR-regulated plant growth have not been established, although their roles in stress responses are well documented. Here, we found that three group III WRKY transcription factors, WRKY46, WRKY54, and WRKY70, are involved in both BR-regulated plant growth and drought response as the triple mutant has defects in BR-regulated growth and is more tolerant to drought stress. RNA-sequencing analysis revealed global roles of WRKY46, WRKY54, and WRKY70 in promoting BR-mediated gene expression and inhibiting drought responsive genes. WRKY54 directly interacts with BES1 to cooperatively regulate the expression of target genes. In addition, WRKY54 is phosphorylated and destabilized by GSK3-like kinase BR-INSENSITIVE2, a negative regulator in the BR pathway. Our results therefore establish WRKY46/54/70 as important signaling components that are positively involved in BR-regulated growth and negatively involved in drought responses.

Genome-wide analysis of WRKY gene family in the sesame genome and identification of the WRKY genes involved in responses to abiotic stresses

“…Previous studies have revealed that one WRKY gene could function in several disparate signaling pathways. For example, AtWRKY70 functions in plant growth, drought response and cell death [52,53]. Interestingly, we found that the SiWRKY17 and SiWRKY43 was induced to highly express under waterlogging stress, while the orthologous genes of them, AtWRKY32 and AtWRKY29, was reported to respond to UV irradiation and heat stress, respectively.…”

MdWRKY9 overexpression confers intensive dwarfing in the M26 rootstock of apple by directly inhibiting brassinosteroid synthetase MdDWF4 expression

“…We also measured BL and CS (a precursor of BL) contents in the transgenic apple line overexpressing MdWRKY9 and the control plants. Due to the low content of BL in apple plants, it was not detected, as in other species (Chen et al ., ). The content of CS in transgenic line 1 overexpressing MdWRKY9 (10.15 ng g −1 ) was only 68% that of the control (14.82 ng g −1 ) (Fig.…”

“…We also measured BL and CS (a precursor of BL) contents in the transgenic apple line overexpressing MdWRKY9 and the control plants. Due to the low content of BL in apple plants, it was not detected, as in other species (Chen et al, 2017).…”

“…In transgenic Brassica napus overexpressing AtDWF4, many WRKYs have reduced expression levels, suggesting that WRKY potentially negatively regulates DWF4 (Sahni et al, 2016). Recent research found that AtWRKY46/54/70 play positive roles in plant growth mainly by regulating BR signaling with a smaller effect on BR biosynthesis (Chen et al, 2017). Taken together, there is no evidence for the direct regulation of BR biosynthesis by WRKY.…”

Identification of plant hormones and candidate hub genes regulating flag leaf senescence in wheat response to water deficit stress at the grain‐filling stage

“…Based on candidate gene association analysis, further research has indicated that OsLG3 plays a positive role in water deficit tolerance in rice by ROS (Xiong et al., ). RNA sequencing analysis of Arabidopsis has also revealed that transcription factors WRKY46 , WRKY54 , and WRKY70 play important roles in promoting BR‐mediated gene expression and inhibiting drought‐responsive genes (Chen et al., ). Additionally, the flowering repressor SHORT VEGETATIVE PHASE (SVP) is induced by drought stress and is associated with promoter regions of ABA catabolic pathway genes CYP707A1/3 and AtBG1 .…”