Inactivating transcription factorOsWRKY5enhances drought tolerance through abscisic acid signaling pathways

Abstract

During crop cultivation, water-deficit conditions retard growth, thus reducing crop productivity. Therefore, uncovering the mechanisms behind drought tolerance is a critical task for crop improvement. Here, we show that the rice (Oryza sativa) WRKY transcription factor OsWRKY5 negatively regulates drought tolerance. We determined that OsWRKY5 was mainly expressed in developing leaves at the seedling and heading stages, and that its expression was reduced by drought stress and by treatment with NaCl, mannitol, and abscisic acid (ABA). Notably, the genome-edited loss-of-function alleles oswrky5-2 and oswrky5-3 conferred enhanced drought tolerance, measured as plant growth under water-deficit conditions. Conversely, the overexpression of OsWRKY5 in the activation-tagged line oswrky5-D resulted in higher susceptibility under the same conditions. The loss of OsWRKY5 activity increased sensitivity to ABA, thus promoting ABA-dependent stomatal closure. Transcriptome deep sequencing and reverse transcription quantitative polymerase chain reaction analyses demonstrated that the expression of abiotic stress-related genes including rice MYB2 (OsMYB2) was upregulated in oswrky5 knockout mutants and downregulated in oswrky5-D mutants. Moreover, dual-luciferase, yeast one-hybrid, and chromatin immunoprecipitation assays showed that OsWRKY5 directly binds to the W-box sequences in the promoter region of OsMYB2 and represses OsMYB2 expression, thus downregulating genes downstream of OsMYB2 in the ABA signaling pathways. Our results demonstrate that OsWRKY5 functions as a negative regulator of ABA-induced drought stress tolerance, strongly suggesting that inactivation of OsWRKY5 or manipulation of key OsWRKY5 targets could be useful to improve drought tolerance in rice cultivars.

Transcriptome-wide identification of WRKY transcription factors and their expression profiles under different stress in Cynanchum thesioides

“…Plants survive in complex and variable environments and are often subjected to various biotic and abiotic stresses, and WRKY transcription factors have important roles in plant growth and development and in coping with adverse stresses ( Chen et al., 2020a ; Chen et al., 2020b ). For example, WRKY transcription factors affect lignin synthesis ( Miyamoto et al, 2020 ) and fruit ripening ( Gan et al, 2021 ) during plant growth and development; additionally, WRKY TFs are involved in plant responses to drought ( Lim et al, 2022 ), salt ( Fang et al, 2021 ), and low temperature ( Zhang et al, 2019a ) and a variety of other stress responses. It has been shown that WRKY transcription factors initiate a response in plants mainly by interacting with the cis-acting element W-box on the target gene promoter, which acts as a transcriptional activator or repressor of downstream gene expression ( Bakshi & Oelmüller, 2014 ).…”

OsWRKY114 Negatively Regulates Drought Tolerance by Restricting Stomatal Closure in Rice

“…Six OsWRKYs (OsWRKY5, OsWRKY11, OsWRKY30, OsWRKY45, OsWRKY47, and OsWRKY55) are known regulators of drought tolerance in rice [ 15 , 16 , 17 , 18 , 19 , 20 ]. To examine the relationships among these TFs, we constructed a phylogenetic tree.…”

“…Rice ( Oryza sativa L.), which is one of the most important monocot crops, has 103 WRKY TFs, including 28 Group III members [ 13 , 14 ]. Among rice WRKY TFs, OsWRKY5, OsWRKY45, and OsWRKY55 decrease drought tolerance, while OsWRKY11, OsWRKY30, and OsWRKY47 increase it [ 15 , 16 , 17 , 18 , 19 , 20 ]. OsWRKY45, OsWRKY47, and OsWRKY55 are WRKY Group III TFs.…”

GmWRKY21, a Soybean WRKY Transcription Factor Gene, Enhances the Tolerance to Aluminum Stress in Arabidopsis thaliana

“…Recent studies have shown that OsWRKY108 was an integrative regulator of P homeostasis and leaf inclination (Wang et al, 2021 ). The inactivated OsWRKY5 enhanced drought tolerance through abscisic acid signaling pathways (Lim et al, 2021 ). At 4°C, overexpression of OsWRKY76 improved the tolerance to low-temperature stress (Babitha et al, 2013 ).…”