Lf. Yourman et al., Genetic analysis of isolates of Botrytis cinerea sensitive and resistant to benzimidazole and dicarboximide fungicides, PHYTOPATHOL, 90(8), 2000, pp. 851-859
A total of 56 isolates of B. cinerea collected from ornamental crops from c
ommercial greenhouses were examined by random amplified polymorphic DNA (RA
PD) fingerprint analyses. Isolates were examined as two independent sets of
35 and 36 isolates, with 15 isolates common to both sets. The isolates had
four phenotypes: 17 were sensitive to two commonly used fungicides, thioph
anate-methyl (a benzimidazole) and vinclozolin (a dicarboximide) ((SSV)-S-T
); 18 were resistant to both fungicides ((RRV)-R-T); 16 were resistant to t
hiophanate-methyl but sensitive to vinclozolin ((RSV)-S-T); and 5 were sens
itive to thiophanate-methyl but resistant to vinclozolin ((SR)V)-R-T. Relat
ionships among the isolates were determined by cluster analyses of mean cha
racter differences using the unweighted pair group method using arithmetic
average and cladograms were constructed. Isolates were clustered primarily
by fungicide-sensitivity phenotype. In one set of greenhouse isolates, 6 of
10 (SSV)-S-T isolates clustered together with a bootstrap confidence value
of 91%. In the other fingerprint set of greenhouse isolates, 9 of 11 (SSV)
-S-T isolates clustered together and had a bootstrap confidence value of 98
%. Isolates resistant to thiophanate-methyl, vinclozolin, or both fungicide
s usually were not clustered with other isolates or were clustered with iso
lates of the same phenotype. To further elucidate these relationships, vari
ant isolates resistant to one or both fungicides were produced on fungicide
-amended agar medium from 14 (SSV)-S-T greenhouse isolates. These 14 (SSV)-
S-T parent isolates, 57 resistant variant isolates, and 11 resistant greenh
ouse isolates were analyzed as three independent RAPD fingerprint sets. Var
iants selected from eight (SSV)-S-T parent isolates were resistant to both
thiophanate-methyl and vinclozolin even though parent isolates were exposed
to only one of the fungicides. Isolates resistant only to vinclozolin ((SR
V)-R-T) had fingerprint patterns similar to and clustered with those of par
ent isolates, while fingerprint patterns of isolates resistant to thiophana
te-methyl (i.e., (RRV)-R-T or (RSV)-S-T), regardless of sensitivity to vinc
lozolin, clustered differently from both those of STSV parent isolates and
those of (SRV)-R-T isolates derived from the same parent. (RRV)-R-T and (RS
V)-S-T variant isolates derived from the same fungicide-sensitive parents o
nly clustered with other variants having the same phenotype.