Induction of systemic resistance in faba bean (Vicia faba L.) to bean yellow mosaic potyvirus (BYMV) via seed bacterization with plant growth promoting rhizobacteria

in a greenhouse experiment, two plant growth promoting rhizobacteria ,,PGPR strains (Pseudo monas fluorescens FB11 and a Rhizobium leguminosarum bv.\ viceae FBG05) isolated from roots of faba bean plants were tested singly and in combination as seed inoculants for induction of systemic resistance in faba bean against bean yellow mosaic potyvirus (BYMV). The results demonstrated that BYMV challenged plants emerged from Pseudomonas inoculated seeds not only showed a pronounced and significant reduction in percent disease incidence (PDI) but also a significant reduction in virus concentration (ELISA) in the challenged plants, compared to the nonbacterized, challenged plants. Rhizobium singly also showed a significant reduction in both PDI and ELISA value, but the reduction was less pronounced than that resulting from Pseudomonas inoculation. Combined inoculation with Pseudomonas and Rhizobium showed no additional significant reduction in PDI or ELISA value compared with Pseudomonas singly. Appreciable and significant increase in both salicylic acid level and peroxidase activity was observed in leaves of all PGPR inoculated plants compared to other treatments. Since the PGPR inoculants (Pseudomonas and Rhizobium) and the pathogen (BYMV) remained spatially separated, it can be concluded that the tested Pseudomonas or Rhizobium strains induced systemic resistance in faba bean against BYMV.