FIGURE 8.

Deletion of speA and putrescine transporters attenuated bacterial invasion and virulence of D. zeae EC1 on rice seeds. (A) Rice seed germination assay. Rice seeds were socked in bacterial suspension containing various amounts of bacterial cells as indicated for 5 h before transferred to plates with moisturized filter papers. The germination rates were counted 5 days later. (B,C) Rice seed invasion assay. Strain EC1 and derivatives were labeled with GFP by in trans expression of the gfp gene. Rice seeds were treated with 100 bacterial cells per mL for 5 h, and then incubated for 24 h at 28°C. The husks of rice seeds were removed for examination under a fluorescence microscope (B) and for bacterial CFU counting (C). The representative photographs were presented and the data shown are the means ± SE (n = 3). ^∗∗P < 0.01.