Seleção e caracterização molecular de isolados de Beauveria bassiana (Bals.) Vuill. submetidos ao contato com o fungicida azoxistrobina

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The objective of this experiment was to study the sensibility of Beauveria bassiana (Bals.) Vuill strains to the fungicide azoxystrobin and promote the strains resistence induction. For that were conducted two experiments. The first test studied the sensibility of the strain of the fungus to azoxystrobin fungicide (Amístar 500 WG), and find out the correlation between the molecular profile and the level of sensibility of the pathogens to fungicide through the RAPD technique. In the second test, four sensitive strains and two tolerant strains were selected , promoting the resistance induction to the fungicide. After the end of induction, the profile of the colonies were compared by RAPD up who suffered induction to the colonies not induced by RAPD. For all studies, the dose of 5 g L-1 of the commercial product was used that inhibited 20% of the germination of the standard strain CG 432. For the sensibility study a test of conidia germination was made for 33 monosporics strains. After selection, two groups was separated a sensitive one and a tolerant to the fungicide. Eight sensitive strains with inhibition of germination superior to 30% were selected (GC 481, CG 21, CG 138, UNIOESTE 40, CB 84, CG 460, CB 17 and CB 39) and seven tolerant strains (CB 102, UNIOESTE 4, UEL 55, CG 458, CB 35, CB 87 in UEL 101) with inhibition of germination between 3 and 10.54%. These two groups of strain were submitted to the molecular characterization by RAPD. It was not possible to observe the correlation between sensitivity to fungicide and molecular profile. In the second study, induction of resistance, ten subcultures of colonies of different strains with and without contact with the fungicide were made. Four sensitive strains were chose (CG 460, CB 17, CB 39 and CB 84), and two tolerant strains UNIOESTE 4 and CB 102. The variables evaluated were: growth, conidia productivity, viability, virulence and the minimum inhibitory concentration (MIC), in addition to evaluate by RAPD possible genetic changes after induction. The two tolerant strains maintained the characteristics evaluated after resistance induction. For sensitive ones, it was observed that CG 460 and CB 17 showed an increase in the growth and conidia productivity in the induced colony in relation to the not induced. All strains showed increased in conidia viability produced in the successive subcultures. With the exception of CB 84 strain, the other strains show difference in virulence when compared with colonies without induction. The molecular analysis of the strain CB 17, by RAPD, showed bands changes after induction, characteristic that can also be observed by the MIC, in which induced colony presented conidia productivity superior to the colony not induced, even at the highest dose of the product.

ASSUNTO(S)

microbiologia agrícola agricultural pests - biological control fungi in agriculture pragas agrícolas - controle biológico fungos na agricultura

ACESSO AO ARTIGO

Documentos Relacionados