Genetic Structure of Botrytis cinerea Populations from Different Host Plants in California

The population structure of Botrytis cinerea was investigated by using transposable elements, DNA fingerprinting generated by microsatellite primed-polymerase chain reaction (MP-PCR), and sensitivity to the hydroxyanilide fungicide, fenhexamid, for 234 isolates collected from fig, grape, kiwifruit, pea, and squash in California. Among 234 isolates tested, 195 had two transposable elements, Boty and Flipper (transposa type), 38 had only the Boty element (Boty type), and one had neither of these elements (vacuma type). Four of these 234 isolates, which belonged to the Boty type, were resistant to fenhexamid. A phenogram generated based on MP-PCR markers showed that the isolates were not clustered based on their source hosts or the presence of transposable elements. Analysis of molecular variance (AMOVA) showed that there were no significant genetic differentiations among isolates collected from grape, kiwifruit, pea, and squash at the Kearney Agricultural Center. A more detailed analysis based on AMOVA partition of the total genetic variance indicated that 96% of the variation occurred within populations. The parsimony tree length permutation (PTLPT) and index of association ( I_A) analyses of MP-PCR data set were consistent with absence of sexual recombination in sampled populations of this pathogen.