FIGURE 4.

Analysis of CaWRKY40 ortholog promoter in response to Ralstonia solanacearum inoculation (RSI) and heat shock (HS) in other plant species. (a) Sequences analysis of DWE^CaWRKY40, DWE^AtWRKY40, DWE^VvWRKY40, DWE^GmWRKY40, DWE^CplWRKY40, and their mutated versions. Underlined nucleotides indicate the mutated sequences of W box motifs. The accession numbers of CaWRKY40 orthologs were as follow: Arabidopsis AtWRKY40 (At1g80840; Xu et al., 2006), grape VvWRKY40 (Wang et al., 2014), soybean GmWRKY40 (ABC26914; Cui et al., 2019), and papaya CplWRKY40 (Pan and Jiang, 2014). (b)–(e) β‐Glucuronidase (GUS) activity driven by DWE^CaWRKY40 (CaDWE), DWE^AtWRKY40 (AtDWE), DWE^VvWRKY40 (VvDWE), DWE^GmWRKY40 (GmDWE), DWE^CplWRKY40 (CplDWE), and their mutated versions in response to CaWRKY40 expression (b), AtWRKY40 expression (c), RSI (d), and HS (e). Agrobacterium tumefaciens GV3101 cells harbouring the CaDWE‐WT, AtDWE‐WT, VvDWE‐WT, GmDWE‐WT, CplDWE‐WT, and their double‐W box‐element (DWE) mutated version were vacuum‐infiltrated into the leaves of pepper plants. The infiltrated pepper leaves were subjected to CaWRKY40 overexpression, AtWRKY40 overexpression, RSI, and HS treatments, respectively, and then kept in the greenhouse. At 48 hr (CaWRKY40 and AtWRKY40 overexpression) or 24 hr (RSI and HS treatments) posttreatments, the treated and agroinfiltrated pepper leaves were harvested for GUS activity measurement. The GUS activity driven by CaDWE‐WT without treatment was set to 1. Data in (b)–(e) represent the mean ± SD of three independent biological experiments. Error bars indicate SD (n = 3) from three independent experiments. Asterisks indicate significant differences determined by Student's t test (*p < .05, **p < .01)