Endophytic fungi as growth promoters in Cucumis sativus and biocontrol of downy powdery mildew

Abstract

Endophytic fungi are microorganisms that live inside plant tissues without causing symptoms to the host; but they provide adaptive advantages such as growth stimulation and disease tolerance. The potential of three strains of endophytic fungi as growth promoters and as biocontrol agents for downy powdery mildew in the creole cultivar Cucumis sativus from Yucatan, Mexico, was evaluated. Concentrations of 1×106 spores of endophytic strains of Aspergillus flavus, Lasiodiplodia pseudotheobromae, and Trichoderma longibrachiatum were inoculated into C. sativus plants under protected conditions. The endophyte T. asperellum was included as a positive control and had been previously evaluated. Growth variables were measured, and powdery mildew damage was assessed using a graphical severity scale. Inoculated strains significantly increased shoot fresh weight, root dry weight, dry biomass, and flowering. Only Trichoderma spp. strains increased root length, but only T. asperellum contributed to plant height and reduced powdery mildew infection.