Figure 4.

WRKY45 Acts Downstream of SA in an Apparently NH1-Independent Pathway.

(A) Responses of WRKY45 expression to various signal compounds. Fully expanded fourth leaves of rice at the four-leaf stage were cut into pieces 2 cm long and immersed in aqueous solutions containing 0.01% Silwet L-77 and the following signal compounds: indole-3-acetic acid (IAA; Sigma-Aldrich), gibberellin G₃ (GA; Wako), kinetin (CK; Sigma-Aldrich), 1-aminocyclopropane 1-carboxylic acid (ACC; Sigma-Aldrich), abscisic acid (ABA; Sigma-Aldrich), brassinolide (BR; Wako), methyl jasmonate (MeJA; Wako), 100 μM BTH, or 1 mM sodium salicylate (Nakalai) for 8 h at 30°C. Total RNAs (5 μg) were extracted, and WRKY45 transcript levels were analyzed by RNA gel blot analysis.

(B) Expression of NH1 in NH1-kd rice plants. Transcript levels of NH1 in untreated wild-type and NH1-kd plants (lines #7 and #14 and T2 homozygote) were examined by RT-PCR.

(C) Responses of WRKY45 and PR-1b expression to BTH in NH1-kd rice plants. Transcript levels of WRKY45 were analyzed by RT-PCR at 4 and 6 h, and those of PR-1b at 24 h, after BTH application to wild-type and NH1-kd (lines #7 and #14 and T2 homozygote) rice plants.

(D) Responses of NH1 expression to BTH in WRKY45-kd rice plants. Transcript levels of NH1 were analyzed 24 h after BTH application to wild-type and WRKY45-kd (lines #3, #8, and #24 and T2 homozygote) rice plants.