Plant–microbe–arthropod (PMA) three-way interactions have important implications for plant health. However, our poor understanding of the underlying regulatory mechanisms hampers their biotechnological applications. To this end, we searched for potential common patterns in plant responses regarding taxonomic groups or lifestyles. We found that most signaling modules regulating two-way interactions also operate in three-way interactions. Furthermore, the relative contribution of signaling modules to the final plant response cannot be directly inferred from two-way interactions. Moreover, our analyses show that three-way interactions often result in the activation of additional pathways, as well as in changes in the speed or intensity of defense activation. Thus, detailed, basic knowledge of plant–microbe–arthropod regulation will be essential for the design of environmentally friendly crop management strategies.
In nature, plants are continuously challenged by biotic stressors such as pathogenic microorganisms and herbivorous pests that often cause important yield reductions in crops. To address global food security issues but also consumer demands for healthier food production, a series of environmentally friendly crop protection strategies need to be employed in modern agriculture. In this chapter, we explore promising opportunities for controlling pests and pathogens of crops on the basis of our current knowledge on molecular, chemical and ecological parameters that determine plant defense. We present evidence about the feasibility of RNA-based molecular tools against a diversity of plant enemies. Moreover, a brief overview of current knowledge on applied aspects of plant defense priming in crop protection is provided in light of our fundamental understanding on mechanisms underlying this phenomenon. We specifically refer to beneficial organisms such as soil microbes and zoophytophagous predators and propose their use as plant vaccination agents, alongside chemicals that could be used to prime plants against future attackers. Endophytic fungi that not only mediate systemic plant resistance against pests or pathogens, but also impact entomopathogenic and plant growth promoting capabilities, are specifically addressed. Finally, we identify knowledge gaps and present future considerations about the use of the proposed biological and molecular control tools in sustainable crop production.