Pseudomonas syringae pv. tomato DC3000 growth in multiple gene knockouts predicts interactions among hormonal, biotic and abiotic stress responses

Among other environmental factors, phytopathogens have key roles in limiting global crop production. While an in-depth understanding of plant-pathogen interactions is therefore necessary to develop sustainable crop protection strategies, the genetic basis of plant-pathogen interactions is poorly understood. In this study, we tested the growth and resistance of an important phytopathogen, Pseudomonas syringae pv tomato DC3000 (Pst DC3000), in 80 gene knockouts, identified previously through genome-wide association mapping of global Arabidopsis thaliana populations. Amongst these, most of the genes are previously known to regulate multiple functions in plants including cellular mechanisms, growth, reproduction, hormonal signaling, and tolerance to both biotic and abiotic stresses (extreme temperature, drought, salinity, pollutants, and nutrient stresses, etc.). The Pst DC3000 demonstrated two distinct growth patterns in all gene knockouts, showing maximum growth after 4 or 7 days of inoculation (DOI). Mostly, the wild-type (Col-0) demonstrated higher phytopathogen growth than almost all gene knockouts after 4 or 7 DOI. The differential abundance of Pst DC3000 in the multiple gene knockouts reveals a number of new genes important for plant defense. Meanwhile, our results and a review of previous literature suggest interaction of plant defense with plant growth, reproduction, hormonal and abiotic stress tolerance. Thus in future studies, a mechanistic understanding of the genetic, ecological and physiological basis of plant-pathogen interactions, and pleiotropic interactions may prove instrumental in developing sustainable plant protection practices.