OOS 16-9 - Predisposition in plant disease: Signal conflicts and synergies in stress hormone pathways and response

Tuesday, August 8, 2017: 4:20 PM
Portland Blrm 257, Oregon Convention Center
Richard Bostock and Tatiana Roubtsova, Department of Plant Pathology, University of California, Davis, CA

During evolution, plants developed finely tuned mechanisms to cope with diverse abiotic and biotic stresses. This is our operational paradigm and many studies affirm cooperative signaling and response to mitigate environmental challenges. Yet we must reconcile the fact that plants often succumb to pathogens and pests that they would normally resist when confronted with transient and relatively mild abiotic stresses. Predisposition results from abiotic stresses occurring prior to or concurrent with attack that affect host susceptibility. Plant responses that are adaptive in the short term may conflict with those for resisting diseases and pests. Abiotic and biotic stress responses are coordinated by complex signaling networks involving phytohormones and reactive oxygen species. Abscisic acid is a global regulator in stress response networks and an important phytohormone in plant-microbe interactions with systemic effects on resistance and susceptibility. However, extensive cross talk occurs among all the phytohormones during stress events, and the challenge is discerning those interactions that most influence resistance and susceptibility. This presentation will overview current understanding of abiotic stress predisposition to biotic challengers. Examples from our research on tomato, orchard trees and woody ornamentals, with emphasis on diseases caused by oomycete and fungal pathogens, will be highlighted.


The environment is seldom optimal for plant growth, and even mild, episodic stresses can predispose plants to various attackers they would otherwise resist. Modern agricultural crops must balance disease and pest resistance, stress tolerance, and growth with associated fitness costs, but how well they do this can depend on selection criteria during breeding as well as on the impact of production practices designed to maximize yields or to conserve increasingly limited resources. An understanding of predisposition is also relevant to issues of stand establishment in restoration ecology and forest health. Identifying convergent points in the stress response circuitry is important for understanding the fundamental biology that underscores the disease/pest phenotype as well as translating research to improve stress tolerance and disease management in production systems.