TaWRKY51 promotes lateral root formation through negative regulation of ethylene biosynthesis in wheat (Triticum aestivum L.)

Abstract

Common wheat (Triticum aestivum L.) is an important staple food crop worldwide. Lateral roots (LRs), as the major component of root architecture, affect water and nutrient uptake in wheat. The phytohormone ethylene is known to affect LR formation; however, the factor(s) modulating ethylene during this process have not yet been elucidated in wheat. Here we identified wheat TaWRKY51 as a key factor that functions in LR formation by modulating ethylene biosynthesis. Wheat TaWRKY51RNA interference lines (TaWRKY51-RNAi) and the homozygous mutants tawrky51-2a and tawrky51-2b all produced fewer LRs than the wild type and negative transgenic plants, whereas the TaWRKY51 overexpression lines (TaWRKY51-OE) had the opposite phenotype. Transcription analysis revealed that 1-aminocyclopropane-1-carboxylic acid synthase (ACS) genes (TaACS2, TaACS7 and TaACS8) involved in ethylene biosynthesis were downregulated in TaWRKY51-OE lines but upregulated in TaWRKY51-RNAi lines. The rate of ethylene production also decreased in TaWRKY51-OE lines but increased in TaWRKY51-RNAi lines compared with their respective negative transgenic controls. Electrophoretic mobility shift and transient expression assays revealed that TaWRKY51 inhibits the expression of ACS genes by binding to the W-box cis-element present in their promoter region. Moreover, overexpression of ACS2 or exogenous application of 1-aminocyclopropane-1-carboxylic acid reversed the phenotype of enhanced LR number in TaWRKY51-OE Arabidopsis lines, and overexpression of TaWRKY51 in the ethylene-overproducing mutant eto1-1 rescued its LR defect phenotype. In addition, genetic evidence demonstrates that TaWRKY51-regulated LR formation is also dependent on ethylene and auxin signaling pathways. Our findings reveal a molecular genetic mechanism by which a WRKY gene coordinates ethylene production and LR formation in wheat.

A WRKY transcription factor, TaWRKY42-B, facilitates initiation of leaf senescence by promoting jasmonic acid biosynthesis

“…Recently, some WRKYs involved biological processes have been studied in wheat. TaWRKY51 affected ethylene production and subsequently promoted lateral root formation [61]. TaWRKY2 was induced by drought, salt, heat, and ABA, and overexpression of TaWRKY2 led to enhanced tolerance of transgenic wheat to drought stress and increased yield [62,63].…”

Transcriptomic Analysis Reveals the Molecular Adaptation of Three Major Secondary Metabolic Pathways to Multiple Macronutrient Starvation in Tea (Camellia sinensis)

“…In response to nitrogen depletion, GL3, which belongs to the bHLH TF family, is strongly induced, and anthocyanin synthesis is activated in seedlings and rosette stage plants [63]. To our knowledge, several members of WRKY families have been verified to respond to phosphate starvation in Arabidopsis, rice, and wheat [64][65][66][67][68]. The WRKY family in tea is characterized only in structure but not in biological function [69].…”

The chaperone MeHSP90 recruits MeWRKY20 and MeCatalase1 to regulate drought stress resistance in cassava

“…The WRKY transcription factor (TF) family is one of the largest gene families in plants (Rushton et al, 2010;Chen et al, 2012;Hu et al, 2013a;Liu et al, 2014;Lei et al, 2017;Hu et al, 2018;Li et al, 2018). WRKY is named after the highly conserved WRKYGQK motif within the WRKY domain of c. 60 amino acids (Eulgem et al, 2000;Rushton et al, 2010).…”