FIG 4.

HrcT functions in regulating the expression of hrpX. (A) pXGUS-mediated glucuronidase activity in X. oryzae pv. oryzicola RS105, RΔhrpG, RΔhrcT, RΔhrcV, and the complemented strains C1RΔhrcT and C2RΔhrcT. Strains were incubated in NB or XOM3 medium for 12 h at 28°C. GUS activity was determined by measuring the OD at 415 nm using 4-MUG as a substrate. (B) Expression analysis of hrpX by real-time qRT-PCR. RNAs were isolated from cultures of X. oryzae pv. oryzicola RS105, RΔhrcT, RΔhrcV, complemented strains C1RΔhrcT and C2RΔhrcT, and RΔhrpG. All strains were incubated in rice suspension cells at 25°C for 16 h, and relative mRNA levels were calculated with respect to the expression level of the corresponding transcript in the wild-type RS105. (C) Expression analysis of hrp genes by qRT-PCR. RNAs were isolated from cultures of the wild-type RS105, RΔhrcT, and RΔhrpX, which were incubated in rice suspension cells at 25°C for 16 h. The relative mRNA levels were calculated with respect to the corresponding transcript in RS105. All the experiments were repeated three times, and similar results were obtained. Data represent the means ± standard deviations of triplicate measurements. 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.