Efficacy of Pseudomonas chlororaphis subsp. aureofaciens SH2 and Pseudomonas fluorescens RH43 isolates against root-knot nematodes (Meloidogyne spp.) in kiwifruit

Abstract

The Root-knot nematodes, Meloidogyne spp., are parasites of many crops and orchards, including kiwifruit trees. The Islamic Republic of Iran is among the leading kiwifruit producers in the world and M. incognita has been found as the dominant species responsible for severe loss of this crop. In order to evaluate the eff ectiveness of antagonistic bacteria on larval mortality, number of galls per plant and egg masses of nematode reduction, fifty local bacterial strains were isolated from root surrounding soils of kiwifruit plants in the northern production areas in Iran. Bacterial antagonists were characterized by morphological, physiological, biochemical and molecular methods. Two representative strains, showing the best nematicidal activity, were identif ed as Pseudomonas chlororaphis subsp. aureofaciens (isolate Sh2) and Pseudomonas fluorescens (isolate Rh43). They increased the percentage of larval mortality to 56:38% and 54:28% respectively in assays in vitro and showed excellent performance also in vivo with consistent reduction of number of galls (67:31% and 55:63%, respectively) and egg mass (86:46% and 84:29%, respectively) in plants. This study indicates that Pseudomonas chlororaphis subsp. aureofaciens isolate Sh2 and Pseudomonas fluorescens isolate Rh43 are good potential biocontrol agents for containing root-knot nematodes in kiwifruit trees.