First report isolation, molecular identification and biological control of Pantoea leaf blight on Phaseolus vulgaris caused by Pantoea eucrina using Trichoderma species in Egypt

Abstract

This study aimed to isolate and identify the bacteria causing severe naturally occurring blight on leaves of common beans sprayed in several places under the governorate of Qena, both physiologically and molecularly. Four isolates were obtained from infected bean plants; however, the isolates' levels of pathogenicity varied. Isolate P-1 was the most virulent one against bean plants under greenhouse conditions. Molecularly, Isolate P-1 showed 99.55% similarity with the type strain of Pantoea eucrina (Accession N0. NR116246T). Trichoderma harzianum and T. viride in vitro and in vivo were evaluated for the protection of bean plants against Pantoea leaf blight. Both biocontrol agents had an inhibitory effect on pathogen growth in in vitro experiments. In a pot experiment conducted in a greenhouse, the soil treated with Trichoderma harzianum and T. viride showed significant reductions in the number of bacterial pathogens and diseases. To our knowledge, this is the first report of isolation of the bacterium Pantoea eucrina from bean in Egypt and examined Trichoderma harzianum and T. viride in vitro and in vivo for controlling Pantoea leaf blight pathogen. It could be concluded that Pantoea eucrina, a new emergency plant pathogen, was originally isolated from Phaseolus vulgaris in Egypt for the first time and caused severe bean leaf blight in Upper Egypt. In vitro and in vivo applications of Trichoderma harzianum and T. viride have the potential to suppress bacterial pathogens, and disease incidence rates, and decrease pathogen populations in the leaves of treated bean plants