Fig 2. Agrobacterium-mediated expression of XopAU induces plant immune responses.

(A-E) N. benthamiana leaves were infiltrated with Agrobacterium strains for the expression of His-XopAU or His-XopAU_K240A driven by an estradiol-inducible system, or carrying an empty vector (EV), and treated with 17β-estradiol 24 h later. (A) Photographs of inoculated areas at 48 h after 17β-estradiol application. (B) Electrolyte leakage at 24 h with or without 17β-estradiol application. The box plot displays 25^th, 50^th (middle line) and 75^th percentiles (n = 5). An asterisk indicates a significant difference (Mann-Whitney U test, p value <0.05) compared to EV. (C) Total protein was extracted from N. benthamiana leaves 8 h after 17β-estradiol application and immunoblotted with the indicated antibodies. Rbs, Rubisco loading control stained by Ponceau S. (D) Leaves of the pepper line ECW30R or the tomato line Hawaii 7981 were infiltrated with Agrobacterium strains as in (A) and photographed at 96 h after 17β-estradiol application. (E) Total protein was extracted from pepper leaves at 8 h after 17β-estradiol application and immunoblotted with the indicated antibodies. (F and G) N. benthamiana plants were infected with TRV, TRV:EDS1, TRV:NDR1 and TRV:RAR1. Leaves of silenced plants were inoculated with Agrobacterium (OD₆₀₀ = 0.02) carrying an empty vector (EV), a vector for expression of His-XopAU from an estradiol-inducible system or Cf4/Avr4 driven by the CaMV 35S promoter. Inoculated leaves were treated with 17β-estradiol 24 h later. (F) Photographs of inoculated areas at 36 h after 17β-estradiol application. (G) Electrolyte leakage at 24 h after 17β-estradiol application. The box plot displays 25^th, 50^th (middle line) and 75^th percentiles (n = 5). An asterisk indicates a significant difference (Mann-Whitney U test, p value <0.05) compared to EV. (A-G) Experiments were repeated at least three times with similar results.