Fig. 2.

Expression of hpa2 in X. oryzae pv. oryzicola strain RS105 when the hrpG, hrpX, or hrpD6 gene is mutated. (A) Schematic map of the promoter region containing the PIP box and −10 box-like motif of hpa2 fused with GUS. (B) Detection of hpa2 expression by RT-PCR. RS105 and the hrpG, hrpX, and hrpD6 mutant strains were incubated in the hrp-inducing medium XOM3, and semiquantitative RT-PCR was performed. PCR products were electrophoretically separated on a 1.2% agarose gel. The 16S rRNA PCR product was used as a control. (C) GUS activities of the hpa2 promoter-GUS reporter in RS105, RΔhrpG, RΔhrpX, and RΔhrpD6. Strains were cultured in either XOM3 or NB medium for 16 h, and GUS activities were then determined by measurement of the OD₄₁₅ using p-nitrophenyl-β-d-glucuronide as a substrate. The experiment was repeated twice, and similar results were obtained. Statistically different data groups are indicated by different letters.