Modulating effect of plant growth-promoting rhizobacteria on wheat-induced resistance to Schizaphis graminum

Abstract

The green bug aphid, S chizaphis graminum , is one of the most serious pests of wheat which cause considerable yield loss in wheat fields. At present, beneficial microorganisms such as plant growth-promoting rhizobacteria (PGPR) need to be incorporated into wheat production to diminish the high risk of heavily insecticide application for environment and health hazards. This study aimed to assess the influence of several PGPR strains, Pseudomonas geniculata, Azospirillum oryzae, Pseudomonas brassicacearum , and Azotobacter chroococcum , applied as seed treatments of wheat, on the life table parameters and foraging behaviour of the green aphid, S. graminum . We investigated the physiological and biochemical responses of wheat plants under aphid stress to elucidate the induced resistance conferred by PGPRs. Preference tests revealed that plants treated with A. chroococcum were the least favoured by aphids at 24 h post-infestation. Furthermore, biological parameters of the aphids exhibited significant variation across treatments, with the highest values recorded in the control group and the lowest in plants treated with A. chroococcum . The intrinsic rate of increase ( r _m ) of the aphids was diminished following the application of PGPR, with the lowest r _m observed in the A. chroococcum treatment. The highest concentrations of proteins, carbohydrates, total phenols, and antioxidant enzymes were detected in infested plants treated with A. chroococcum 72 h post-infestation. According to our results, A. chroococcum emerged as the most effective treatment for enhancing both antixenosis and antibiosis resistance in wheat against S. graminum , suggesting its significant potential for integration into pest management strategies in wheat cultivation.