FIGURE 4.

The effect of reduced NO production on Botrytis cinerea infections of sitiens. (A) Representative B. cinerea lesion phenotypes in cv. Ailsa Craig and sitiens sprayed with either water or 5 mM Nitro-L-arginine methyl ester (L-NAME); an inhibitor of NO production. Note the patterns of water-soaking (tissue collapse) and necrosis (black). Bars = 0.5 cm. (B). B. cinerea fungal DNA content in 1 cm² diameter cored lesions isolated from 4 weeks old control cv. Ailsa Craig (AC), sitiens (SIT) sprayed 1 h prior to spot-inoculation with B. cinerea, sprayed with either L-NAME (L) or D-NAME (D; an inactive L-NAME isomer, 5 mM Nitro-d-arginine methyl ester) sampled at 72 h post-infection. Results are expressed as fold increase in biomass compared to t = 0 samples. Mean measurements (n = 5 cores) ±SE following inoculation within B. cinerea are given. Significant differences are indicated with letters. (C) NO production measured at 6 h (peak NO production; see Figure 1A) following spraying conidial suspensions of B. cinerea of whole 4 weeks old tomato sitiens plants. Three treatments were assessed; untreated sitiens plants (SIT), plants sprayed 24 h prior to inoculation with B. cinerea with either L-NAME (SIT-L-NAME) or D-NAME (SIT-D-NAME). Mean NO production was measured in three plants per treatment using a QCL system. Significant differences are indicated with letters.