Infection of Capsicum annuum cv. California Wonder by wild or gene-silenced Phytophthora capsici. Two 10-μl drops of zoospore suspension at 102, 103 or 104 ml-1 were applied to hypocotyl of pepper seedling and disease was assessed after 5-day incubation at 26°C. (A, B, C) Symptoms on seedlings inoculated with wild type at 102, 103 and 104 zoospores ml-1, respectively. (D) Disease incidence of seedlings inoculated with wild or ribose phosphate isomerase (RPI) gene-silenced strains (N = 6). (E) RPI expression in transiently silenced lines (T1) on day 14 after transfer from7 day- old regenerated transformants (T0) treated with dsRNA as indicated by the RT-PCR products of RPI compared with equal amounts of endogenous control actin from the T1 mutant RNA.