The plant growth-promoting rhizobacterium <i>Azospirillum brasilense</i> reduces symptoms and aphid population growth on wheat plants infected with barley yellow dwarf virus

There is increasing interest in the potential of plant growth-promoting rhizobacteria (PGPR) in agriculture to improve plant quality and control pests and diseases. Emerging evidence indicates that some PGPR can influence interactions between plants and their pathogens, while less work has explored whether PGPR may also influence interactions between plants and arthropod vectors. We address this issue in a major agricultural pathosystem involving wheat infection by barley yellow dwarf virus (BYDV), the most economically important aphid-transmitted viral disease of cereal crops. We found that plant association with the PGPR <i>Azospirillum brasilense</i> mitigated both viral effects on plant growth and population growth of the BYDV aphid vector, <i>Rhopalosiphum padi</i>. Although effects varied across <i>A. brasilense</i> strains, PGPR treatments that attenuated virus effects were also associated with reduced induction of salicylic acid in response to infection, suggesting PGPR inoculation may induce systemic resistance against BYDV. These findings suggest that PGPR may have significant capacity for application in the sustainable management of crop growth. However, further investigation of the complex interactions among PGPR, plants, pathogens and their vectors is needed to better understand this potential.