How does resistance differ from tolerance in plants?

While often used interchangeably in casual conversation, resistance and tolerance are two distinct strategies plants use to cope with pathogens.¹ The key difference lies in how the plant interacts with and is affected by the pathogen.

• Resistance: This is the plant's ability to limit or prevent pathogen infection and multiplication.² A resistant plant actively fights the pathogen, often preventing it from establishing a successful infection or severely restricting its spread. This is an active defense mechanism.³
  • Effect on Pathogen: Pathogen growth, reproduction, and spread are significantly reduced.⁴
  • Effect on Plant: The plant shows few to no disease symptoms and maintains high health and yield.
  • Analogy: Resistance is like a castle with strong walls, guards, and weapons that actively repel an invader, preventing them from getting inside and causing damage.
• Tolerance: This is the plant's ability to endure a pathogen infection and minimize the damage to its own fitness or yield.⁵ A tolerant plant may be just as infected as a susceptible one (i.e., the pathogen multiplies freely), but it doesn't "get as sick." It can still grow, photosynthesize, and produce a reasonable yield despite the infection.⁶
  • Effect on Pathogen: The pathogen is allowed to grow and reproduce, often to high levels.
  • Effect on Plant: The plant shows symptoms, but its overall growth and yield are not significantly reduced compared to an uninfected plant.
  • Analogy: Tolerance is like a city that, despite being occupied by an invader, has robust infrastructure and resilient citizens who continue their daily business, minimizing the overall disruption and economic loss.