FAULL, J. L.

MELO, I. S. de

VALENTE, A. M. M. P.

VILELA, E. S. D.

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P4.19 Antagonistic Properties of Bionectria sp. 6.21 Against PlantPathogenic FungiItamar s. tvteto', Elke s. o. vilelo', Angelo M. M. P. valente' and Jane L. Faul/2'Laboratotv of Environmental Microbiology, Embrapa Environment,Rod. SP340, Km 127,5, CP. 69, CEP: 13820-000, Jaguariúna, SP, Brazil2Birkbeck College, London University, London, UKCorresponding mail: ItamarS.Melo.itamar@cnpma.embrapa.brAli living organisms are subject to parasitism or competition. The study of these interactions hasled to the identification of many potential opportunities for the use of living organisms to protectcrops against fungal and bacterial diseases. A wide range of mycoparasites have been used forprotecting a number of important soilborne plant pathogens. However, there has been littlecommercial success in the field, and this failure may reside in the lack of understanding of themode of action of the antagonists. Naturally occurring new species of soil fungi should be assessedfor their biocontrol ability, as naturally occurring biological control is an effective factor leading toecological balance between pathogens and their antagonists. In this study, a Bionectria sp. strain6.21 isolated from citrus rhizosphere was evaluated for its potential in inhibiting the growth ofRhizoctonia solani and Pythium aphanidermatum. R. solani was highly susceptible to infection bythe mycoparasite. Scanning electron microscopic studies revealed that penetration of host cells isapparently accomplished by both associated with morphological changes of the host fungal cell,characterized by cytoplasm disorganization, suggesting that the mycoparasitism is one of themode of action by which Bionectria sp. attacks its host. This strain showed to be able to produceendoglucanase and chitinase enzymes. Bionectria sp. 6.21 produced also two bioactivemetabolites, with moderate to strong activity against P. aphanidermatum and R. so/ani. Inconclusion, these results provide evidence that Bionectria sp. 6.21 has the potential to beco me agood candidate for biological control due to the different modes of action.199

Antagonistic properties of bionectria sp. 6.21 against plant pathogenic fungi.

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