FIG 6.
Detection of the HR in tobacco and pathogenicity in rice. (A and B) Symptoms induced by infiltration of X. oryzae pv. oryzicola strains (suspended in water, OD600 = 0.3) into leaves of rice cv. IR24 (susceptible to X. oryzae pv. oryzicola) with a needleless syringe. Photographs were taken 3 dpi. (C) BLS lesion lengths in adult rice (2 months old) inoculated by the leaf-needling method was measured 14 dpi. (D) Bacterial growth in inoculated rice leaves. Bacteria were recovered from inoculated leaves daily for a period of 4 days. (E) Assay for the HR in tobacco (N. benthamiana) inoculated with bacterial strains adjusted to the following concentrations: OD600 = 0.3 (3 × 108 CFU/ml) and OD600 = 0.01 (1 × 105 CFU/ml). Strains are identified by numbers as follows: 1, X. oryzae pv. oryzicola RS105; 2, mutant RΔhrcT; 3, hrcT-complemented strain C1RΔhrcT; 4, C2RΔhrcT; 5, C2RΔhrcTXac, RΔhrcT containing hrcT from X. axonopodis pv. citri in trans under the T3 promoter; 6, C2RΔhrcTRs, RΔhrcT containing hrcT from R. solanacearum GMI1000 in trans under the T3 promoter; 7, CRΔhrcTPst, RΔhrcT containing hrcT from P. syringae pv. tomato DC3000 in trans under the T3 promoter; 8, RΔhrcV (hrcV mutant, negative control). Tobacco leaves were inoculated with the above-listed strains by a needleless syringe, and HRs were scored 24 and 48 hpi, respectively. The experiments were repeated three times. Data represent the means ± standard deviations from three replicates. Asterisks above columns represent significance based on a paired, two-tailed Student t test relative to the wild type. **, P = 0.01; *, P = 0.05.