Variabilidade morfogenética e virulência de populações massais e mosnospóricas de Colletotrichum lindemuthianum e ocorrência de C. cliviae, pela primeira vez, em Phaseolus vulgaris

Abstract

Bean anthracnose caused by the fungus Colletotrichum lindemuthianum, is the most importante disease of crop. The fungus has high morphological, pathogenic and genetic variability, included found between isolates from same race. There are few studies that explore the variability that exists within massal population, and the use of a single monosporic culture per isolate is standardized. The aime of this study was evaluate the morphological, pathogenic and genetic variability of monosporic populations of the same mass population of C. lindemuthianum. Bean samples from different regions of Rio Grande do Sul, twelve mass isolates and ten monosporic from each massal were obtained, 131 isolates totally. Each Massal isolates were identified by the binomial system in bean differentiators. Morphocultural characterization was performed, considering the shape and color of the colonies, mycelial growth index, final colony diameter, sporulation and conidia shape. The differences were found by multivariate analysis and by the Scott-Knott test 5%. Forty-three isolates were selected to assess virulence when inoculated in seedlings, and transmission rate when inoculated in seeds of Pérola cultivar. From sixtysix isolates molecular characterization was performed using six URP markers. Similarity dendrograms were constructed using the UPGMA method using the Jaccard coefficient. As results, races 64, 75, 81, 337, 377, 857, 1361, 2041 and 2045 were identified. Morphological differences were found between monosporics from the same mass population, with emphasis on the isolates of LSPCL1, LPSCL15 and LSPCL20. Results of virulence and seed-seedling transmission showed differences in seedling disease rates and transmission rates between monosporic isolates, being expressive within the groups of isolates LPSCL15, LSPCL16 and LSPCL18. Molecular analysis demonstrated the existence of genetic variability among monosporic isolates from a mass population, mainly within the population of LPSCL20, LSPCL16 and LSPCL11 isolates. On the other hand, from leaves with anthracnose symptoms, was isolated a pathogen shown reproductive structures associated with sexual phase in fungi. Morphological, pathogenic and genetic characterization was performed to identify the causal agent. The fungus showed formation of periteciums, unitunicated asci and ellipsoid to curved ascospores, in Mathur culture medium. The pathogenicity test showed that the fungus caused lesions on Campeiro bean leaves and formed fertile periteciums on their surface. The molecular analysis of the ITS2, GAPDH and TUB2 regions, revealed that the new causal agent of disease in bean corresponds to the teleomorphic phase of C. cliviae