When two negatives make a positive: the favorable impact of the combination of abiotic stress and pathogen infection on plants

Combined abiotic and biotic stresses modify plant defense signaling, leading to either the activation or suppression of defense responses. Although the majority of combined abiotic and biotic stresses reduce plant fitness, certain abiotic stresses reduce the severity of pathogen infection in plants. Remarkably, certain pathogens also improve the tolerance of some plants to a few abiotic stresses. While considerable research focuses on the detrimental impact of combined stresses on plants, the upside of combined stress remains hidden. This review succinctly discusses the interactions between abiotic stresses and pathogen infection that benefit plant fitness. Various factors that govern the positive influence of combined abiotic stress and pathogen infection on plant performance are also discussed. In addition, we provide a brief overview of the role of pathogens, mainly viruses, in improving plant responses to abiotic stresses. We further highlight the critical nodes in defense signaling that guide plant responses during abiotic stress towards enhanced resistance to pathogens. Studies on antagonistic interactions between abiotic and biotic stressors can uncover candidates in host plant defense that may shield plants from combined stresses. Certain abiotic and biotic stress combinations are less damaging than individual stresses. This is an untapped facet in crop improvement. We review studies on positive stress combinations, highlighting underlying mechanisms and critical regulators.

Automated summary

Combined abiotic and biotic stresses can either activate or suppress plant defense responses by modifying plant defense signaling. While most combined stresses reduce plant fitness, certain abiotic stresses can reduce the severity of pathogen infection, and certain pathogens can improve plant tolerance to abiotic stresses. The positive side of combined stress remains hidden despite the extensive research on the detrimental impact of combined stresses on plants.