Rhizospheric microorganisms as potential biocontrol agents against Phytophthora austrocedri

Abstract

Austrocedrus chilensis [D.Don] Pic. Serm. et Bizarri (Pinales: Cupressaceae) is a keystone tree species in South America. Mortality of A. chilensis has been reported over most of its distribution in Argentina, and Phytophthora austrocedri has been identified as the causal agent. The aim of this work was to evaluate rhizospheric microorganisms present in A. chilensis roots as biocontrol agents against P. austrocedri. Mycelial growth of P. austrocedri was inhibited by seven fungal and four bacterial isolates in vitro. Interaction among isolates and P. austrocedri was microscopically studied. Isolates with high in vitro fungistatic or fungicide performance were molecularly identified and inoculated in plants to evaluate their ability to reduce the effect of the pathogen. Two of the bacterial isolates were able to reduce the symptoms in A. chilensis seedlings inoculated with P. austrocedri. These findings are promising since they may contribute to the development of a biocontrol strategy for the disease.