Fig. 1
Effects of pesticide application on genetic transmissibility within B. cereus group populations in sprayed plots. A: Ideal model of self-transmissibility and mobility within B. cereus group in confined niches. (a): Classification of isolates based on transmissibility. Orange: isolate with self-conjugative and mobilizing capability (T+M+); pink: isolate with mobilization but no self-conjugative capability (T−M+); dark gray: potential host (R); light gray: non-host (R0); (b): Proposed changes in genetic population in a confined plot with or without transmissibility. B: Effects of pesticide application on genetic transmissibility within B. cereus group populations in 2017 (Y1) and 2018 (Y2). Non-conjugative but mobilizable plasmid pBC16 carrying tetracycline (Tet) resistance gene was used as an indicator for transmissibility and mobility. Transconjugants containing mobilizable plasmids were first screened on double-resistant plates. Primer pairs specific to chromosomal background of recipient and plasmid pBC16, respectively, were used to confirm correct transconjugants. Each mating experiment was repeated three times and isolates with > 2 positive results were defined as having mobility. In total, 684 isolates (ca. 40/set) were tested in mobility experiments. P < 0.1: *; P < 0.01: **; P < 0.001: ***; P < 0.0001: ****