Biotechnological Studies Of Several Isolates Of Fluorescent Pseudomonads From Algerian Soil As Potential Biological Control Agents Against Olive Wilt Pathogen Verticillium Dahliae

Résumé: Verticillium wilt of olive (Olea europea L.) caused by Verticillium dahliae is difficult to manage and control in Algeria and worldwide. The present investigation was undertaken to search indigenous pseudomonads population in the Algerian habitats for isolates with potential antagonism against V. dahliae. Twenty one indigenous isolates of fluorescent pseudomonads were obtained from the rhizosphere and non-rhizosphere field soil under healthy and Verticillium-infected olive orchards at different locations in Algeria (Boumerdes, Tizi ouzou, Bouira). The phenotypic diversity ofthose isolates was characterized according to their biochemical and physiological properties and their genotypic diversity was ascertained on the basis of their repetitive extragenic palindromic patterns by PCR technology. Numerical analysis of that characterization showed clustering of those isolates and high level of similarity (80%) among all of them. Their antagonistic activity in vitro against two pathogenic isolates of V. dahliae belonging to defoliating and non-defoliating pathotypes, respectively was bio-assayed on two types of culture media (KB and PDA). Seven isolates caused total inhibition of mycelium growth and microsclerotia formation on KB medium. Ten isolates caused only inhibition of microsclerotia formation on PDA medium.

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