A WRKY transcription factor confers aluminum tolerance via regulation of cell wall modifying genes

Abstract

Modification of cell wall properties has been considered as one of the determinants that confer aluminum (Al) tolerance in plants, while how cell wall modifying processes are regulated remains elusive. Here, we present a WRKY transcription factor WRKY47 involved in Al tolerance and root growth. Lack of WRKY47 significantly reduces, while overexpression of it increases Al tolerance. We show that lack of WRKY47 substantially affects subcellular Al distribution in the root, with Al content decreased in apoplast and increased in symplast, which is attributed to the reduced cell wall Al‐binding capacity conferred by the decreased content of hemicellulose I in the wrky47‐1 mutant. Based on microarray, real time‐quantitative polymerase chain reaction and chromatin immunoprecipitation assays, we further show that WRKY47 directly regulates the expression of EXTENSIN‐LIKE PROTEIN (ELP) and XYLOGLUCAN ENDOTRANSGLUCOSYLASE‐HYDROLASES17 (XTH17) responsible for cell wall modification. Increasing the expression of ELP and XTH17 rescued Al tolerance as well as root growth in wrky47‐1 mutant. In summary, our results demonstrate that WRKY47 is required for root growth under both normal and Al stress conditions via direct regulation of cell wall modification genes, and that the balance of Al distribution between root apoplast and symplast conferred by WRKY47 is important for Al tolerance.

Dysfunction of the 4‐coumarate:coenzyme A ligase 4CL4 impacts aluminum resistance and lignin accumulation in rice

“…Due to its negatively charged carboxylic groups, the pectic matrix is generally considered to be the major Al binding site of the cell wall, resulting in toxicity (Blamey et al, 1990;Chang et al, 1999;Horst et al, 2010). Nevertheless, recent studies have demonstrated that hemicellulose contributes significantly to Al accumulation and Al-induced root growth inhibition in Arabidopsis thaliana (Yang et al, 2011;Zhu et al, 2012;Li et al, 2020). Arabidopsis hemicellulose is mainly composed of non-charged xyloglucan, which has been proposed to be the principal binding site for Al, although the structural features of xyloglucan required for the binding of Al are still unclear (Zhu et al, 2012).…”

TaGST1 Gene and Its Regulatory Factor WRKY74 Mediate Copper Tolerance by Effecting Glutathione Accumulation in Wheat

“…Although it sequence had high similarities to AetWRKY6, TaWRKY, and TaWRKY5 in Triticum or OsWRKY30 in rice, their functions in responses to metal stresses have not been identi ed. Similar to other plant WRKY transcription factors (32,33,36,39), TaWRKY74 was more markedly induced by Cu stress compare to Al and Cd stress ( Fig. 5), suggesting that the TaWRKY74 transcription factor plays more key roles in the response to Cu stress in wheat.…”

“…The WRKY transcription factors, the largest families of plants transcription factors, have been reported to play crucial roles by regulating the downstream target gene expression in response to various metal stresses. Under Al stress, for instance, OsWRKY22 in rice, WRKY46 and WRKY47 in Arabidopsis, were participated in Al tolerance by regulating the related genes expression [32,33,39]. Additionally, ZmWRKY4 in Zea mays, WRKY53 in Thlaspi caerulescens, ThWRKY7 in Tamarix hispida, and WRKY12 and WRKY13 in Arabidopsis have been reported to respond to Cd stress via different pathways [35,[58][59][60].…”

“…WRKY transcription factors, which are characterized by diagnostic WRKY domains, speci cally recognize and bind with the [(T/C)TGAC(T/C)] sequences (W-box, cis-acting elements) on the promoters of its target genes [31]. For instance, AtWRKY47 directly regulates the expression of ELP and XTH17 responsible for cell wall modi cation under Al stress [32]; and OsWRKY22 positively controls the expression of OsFRDL4 via W-box cis-acting elements on its promoter under Al stress conditions in rice [33]. Additionally, AtWRKY12 negatively regulates cadmium tolerance by repressing GSH1 expression [34], while AtWRKY13 positively mediates cadmium tolerance by activating the expression of AtPDR8 [35].…”

Recent Advances in Understanding Mechanisms of Plant Tolerance and Response to Aluminum Toxicity

“…Recently, HvHOX9, a novel homeobox-leucine zipper transcription factor, was identified to play a critical role in Al tolerance in barley by decreasing root CW Al binding, increasing apoplastic pH in the root, and silencing of HvHOX9 which increased Al accumulation in root CW and decreased H + influx after Al exposure [136]. Li et al showed that WRKY47 was involved in altering Al distribution between the apoplast and symplast by regulating the genes responsible for CW modification, thereby improving Al tolerance [125]. Lou et al reported that a NAC-type TF, VuNAR1, is involved in Al resistance in rice beans, and overexpression of VuNAR1 induced higher WAK1 expression and low pectin content via directly binding to the WAK1 promoter and regulating CW pectin metabolism [138].…”