Many WAKs have been shown to be involved in hormonal signals. Arabidopsis WAK1 is induced by both SA and the SA analog 2,2-dichloroisonicotinic acid (INA), and ectopic expression of the entire WAK1 or the kinase domain alone was shown to provide resistance to lethal SA levels [36]. According to cDNA microarray analysis in Arabidopsis, AtWAK1 is induced by MeJA and ethylene [37]. In this study,

Smoothened antagonist qRT-PCR analyses revealed that TaWAK5could be induced by application of exogenous SA, ABA, and MeJA. Although an antagonistic interaction between SA- and JA-dependent signaling has been suggested [38], [39] and [40], in some cases, SA does not inhibit JA biosynthesis and may even contribute to JA-mediated signaling pathway function [41]. In Arabidopsis, concentrations of both SA and JA and the timing of initiation of SA and JA signaling are important for the outcome of the complex SA-JA signal interaction [42] and [43]. ABA has been shown to interact with the SA-JA network. ABA has been suggested to affect JA biosynthesis and resistance against the JA-inducing, necrotrophic pathogen Pythium irregular [23] and [24], and to suppress SA-dependent disease resistance [44]. Related to the role

of phyto-hormones in WAK expression, the region upstream of the start codon (1000 bp) of TaWAK5 was analyzed in this study. The promoter region contained one ABRE-like motif (ACGTG), but no SA-, or JA-responsive elements (shown in Table S3). Several studies have suggested that modulation of gene expression is accomplished through the interaction of induced regulatory proteins and specific DNA regions [45], [46] and [47]. For instance, the induction of a dehydration-responsive gene, rd22, Y-27632 ic50 is mediated by ABA. MYC and MYB recognition sites in the rd22 promoter region function as cis-acting elements that interact specifically with AtMYC2 and AtMYB2; transgenic plants overexpressing AtMYC2 and/or AtMYB2 cDNAs have higher sensitivity to ABA [47]. In this study, TaWAK5 promoter had five binding sites of an ABA-regulated protein, two of a SA-regulated protein, and one of a JA-regulated protein ( Fig. S1), suggesting that TaWAK5 was also regulated possibly through SA-, ABA-, and MeJA-hormones.

In this study, VIGS, which has been an efficient tool for rapidly analyzing the functions of plant genes [48], [49], [50] and [51], Celastrol was also used to evaluate the disease resistance role of TaWAK5. In wheat, infection with barley stripe mosaic virus (BSMV) constructs carrying a fragment of the resistance gene Lr21 caused conversion of incompatible interactions of wheat and leaf rust pathogen to compatible reactions after the gene silencing, whereas infection with a control construct or one that silences phytoene desaturase gene had no effect on resistance or susceptibility [33]. Knocking down the transcript levels of three wheat RLK genes TaRLK-R1, TaRLK-R2, or TaRLK-R3 individually or all together by VIGS and the suppression of TaHsp90.2 or TaHsp90.