Differential Responses of Gγ-Deficient Mutants to Pathogen Attack and MeJA Treatment.
(A) Susceptibility of wild-type plants (Col-0) and Gβ- and Gγ-deficient mutants to F. oxysporum. For each genotype, 48 plants were inoculated and the average percentage of decayed plants per line was scored in three independent experiments. Error bars represent se.
(B) Inhibition of rosette growth after F. oxysporum inoculation expressed relative to the mean growth of the same genotype after mock inoculation. Mean values and corresponding sd were calculated from 48 inoculated and 24 mock-inoculated plants for each genotype.
(C) Same as (A) for wild-type Ws ecotype and gpa1-1 and agg1-1w mutants.
(D) Expression of the defense-related gene PDF1.2 in response to A. brassicicola infection. Two-week-old wild-type and mutant plants were sprayed with an A. brassicicola spore solution (106 spores/mL). Total RNA was extracted from infected leaf tissue at 20 h after inoculation. The blot was hybridized with a PDF1.2 probe, stripped, and reprobed with a ribosomal probe as a control.
(E) Quantitative estimation of lesion development after A. brassicicola infection (106 spores/mL). The area covered by necrotic tissue was expressed as a percentage of the inoculated area. Data points represent averages with sd of at least 30 lesions for each genotype. Letters indicate statistically significant differences between genotypes (Student's t test, P < 0.05, n = 20).
(F) Germination percentages of at least 100 seeds pretreated with 10 μM paclobutrazol and sown on 0.5× MS, 1% sucrose, and 0.8% agar plates with or without 50 μM MeJA. Germination was assessed at 2 d after transferring plates to 23°C in continuous light. Bars represent averages with se of three independent experiments.
(G) Root growth inhibition in response to MeJA treatment. Seedlings were grown for 14 d on 1× MS and 2% sucrose plates supplemented with or without 50 μM MeJA. At least 30 seedlings were measured for each genotype. Data are presented as percentages of the length of treated roots compared with their respective nontreated controls. Bars represent averages with sd. Letters indicate statistically significant differences between genotypes (Student's t test, P < 0.05, n = 30).