Variabilidade genética e avaliação de sensibilidade a fungicidas em sclerotinia sclerotiorum proveniente de cultivo irrigado de feijoeiro
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2015-03-27
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Universidade Federal de Goiás
Resumo
Sclerotinia sclerotiorum is a phytopathogenic fungus that infects more than 400 plant
species, including common bean. Genetic variability studies in connection with
phenotypic traits of agronomic interest are important to drive the control strategies
against this pathogen. The aims of this study were: to evaluate the genetic variability,
fungicide sensitivity, aggressiveness and to determine the proportion of MAT (Mating
Type) alleles of 79 isolates of S. sclerotiorum distributed in four populations from
common bean. Two populations represented a single sampling location in two
different times (2000 and 2013 growing seasons). To evaluate the fungicide
sensitivity a cell viability test based on the alamarBlue dye using mycelial growth was
standardized. Dose-response curves for fluazinam, procymidone and benomyl were
estimated using this test and were compared with dose-response curves estimated
by the mycelial growth inhibition on PDA plate and the FRAC (Fungicide Resistance
Action Committee) protocol. Despite the differences to assess the fungicide
sensitivity between the three methods, the dose-response curves showed similar
trends for the three fungicides. The fungicide sensitivity assessment at the four
populations showed low sensitivity to benomyl in the Planaltina population.
Furthermore, this population presented a principally clonal population structure, with
a haplotype represented by 18 out of 20 isolates. Significant population differentiation
in all pairwise comparisons of phi, except the comparison between EV_2013-NH,
was detected. Five genetically homogeneous groups were inferred by the DAPC
analysis. No group was conformed by isolates from the four populations. Only two
haplotypes between the two populations from the same sampling location were
shared. The hypothesis of random mating was rejected at the four populations;
however this hypothesis was not rejected at the two major populations inferred by the
DAPC analysis. The screening of mating type locus showed a dominance of Inv+
isolates and a high proportion of Inv+/Inv- isolates (presumable heterokaryons).
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ARBOLEDA, William Andrés López. Variabilidade genética e avaliação de sensibilidade a fungicidas em sclerotinia sclerotiorum proveniente de cultivo irrigado de feijoeiro. 2015. 79 f. Dissertação (Mestrado em Biologia) - Universidade Federal de Goiás, Goiânia, 2015.