Soybean WRKY‐type transcription factor genes,GmWRKY13, GmWRKY21, andGmWRKY54, confer differential tolerance to abiotic stresses in transgenicArabidopsisplants

Abstract

Summary WRKY‐type transcription factors have multiple roles in the plant defence response and developmental processes. Their roles in the abiotic stress response remain obscure. In this study, 64 GmWRKY genes from soybean were identified, and were found to be differentially expressed under abiotic stresses. Nine GmWRKY proteins were tested for their transcription activation in the yeast assay system, and five showed such ability. In a DNA‐binding assay, three proteins (GmWRKY13, GmWRKY27 and GmWRKY54) with a conserved WRKYGQK sequence in their DNA‐binding domain could bind to the W‐box (TTGAC). However, GmWRKY6 and GmWRKY21, with an altered sequence WRKYGKK, lost the ability to bind to the W‐box. The function of three stress‐induced genes, GmWRKY13, GmWRKY21 and GmWRKY54, was further investigated using a transgenic approach. GmWRKY21‐transgenic Arabidopsis plants were tolerant to cold stress, whereas GmWRKY54 conferred salt and drought tolerance, possibly through the regulation of DREB2A and STZ/Zat10. Transgenic plants over‐expressing GmWRKY13 showed increased sensitivity to salt and mannitol stress, but decreased sensitivity to abscisic acid, when compared with wild‐type plants. In addition, GmWRKY13‐transgenic plants showed an increase in lateral roots. These results indicate that the three GmWRKY genes play differential roles in abiotic stress tolerance, and that GmWRKY13 may function in both lateral root development and the abiotic stress response.

A systems biology perspective on the role of WRKY transcription factors in drought responses in plants

“…These encouraging crop plant-based results are supplemented by others in the model plant Arabidopsis and further evidence came from altered plant responses to different abiotic stresses following the overexpression of three stress-inducible soybean wRKY genes in Arabidopsis. Zhou et al (2008) revealed enhanced cold tolerance in comparison to wild type when GmWRKY21 was overexpressed. In comparison, GmWRKY54-overexpressing plants were shown to be more salt and drought tolerant and GmWRKY13 overexpression resulted in increased sensitivity to salt and mannitol stresses (Zhou et al 2008).…”

“…Zhou et al (2008) revealed enhanced cold tolerance in comparison to wild type when GmWRKY21 was overexpressed. In comparison, GmWRKY54-overexpressing plants were shown to be more salt and drought tolerant and GmWRKY13 overexpression resulted in increased sensitivity to salt and mannitol stresses (Zhou et al 2008).…”

The rice transcription factor OsWRKY47 is a positive regulator of the response to water deficit stress

“…Rushton et al 2010;Chen et al 2012;Tripathi et al 2014;Schluttenhofer and Yuan 2015). Overexpression of soybean GmWRKY13 in Arabidopsis conferred higher sensitivity to salinity and osmotic stress in the transgenic plants (Zhou et al 2008). On the other hand, the expression of the barley HvWRKY38 in Paspalum notatum Flugge increased the drought tolerance of the transgenic plants (Xiong et al 2010).…”

Overexpression of AtSZF2 from Arabidopsis Showed Enhanced Tolerance to Salt Stress in Soybean

“…An increase in the GmbZIP62 (Liao et al 2008) was also observed in the transgenic plants. The RNA level of the abiotic stress responsive genes, ethylene response factor gene GmERF3 (Zhang et al 2009) and WRKY-type transcription factor gene GmWRKY54 (Zhou et al 2008) barely increased. In case of the osmotin-like protein b isoform gene GmOLPb (Tachi et al 2009) and plant-homeo-domain gene GmPHD2 ), their expressions enhanced significantly in the transgenic plant.…”