Centro de Biotecnología y Genómica de Plantas (UPM-INIA) and E.T.S. Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, 28223 Madrid, Spain.
Int J Mol Sci. 2018 Mar 11;19(3):810. doi: 10.3390/ijms19030810.
The two major mechanisms of plant defense against pathogens are resistance (the host's ability to limit pathogen multiplication) and tolerance (the host's ability to reduce the effect of infection on its fitness regardless of the level of pathogen multiplication). There is abundant literature on virtually every aspect of plant resistance to pathogens. Although tolerance to plant pathogens is comparatively less understood, studies on this plant defense strategy have led to major insights into its evolution, mechanistic basis and genetic determinants. This review aims at summarizing current theories and experimental evidence on the evolutionary causes and consequences of plant tolerance to pathogens, as well as the existing knowledge on the genetic determinants and mechanisms of tolerance. Our review reveals that (i) in plant-pathogen systems, resistance and tolerance generally coexist, i.e., are not mutually exclusive; (ii) evidence of tolerance polymorphisms is abundant regardless of the pathogen considered; (iii) tolerance is an efficient strategy to reduce the damage on the infected host; and (iv) there is no evidence that tolerance results in increased pathogen multiplication. Taken together, the work discussed in this review indicates that tolerance may be as important as resistance in determining the dynamics of plant-pathogen interactions. Several aspects of plant tolerance to pathogens that still remain unclear and which should be explored in the future, are also outlined.
植物抵御病原体的两大主要机制是抗性（宿主限制病原体繁殖的能力）和耐受性（宿主降低感染对其适应性影响的能力，而不考虑病原体繁殖水平）。几乎关于植物对病原体抗性的每一个方面都有大量的文献。尽管对植物病原体的耐受性相对了解较少，但对这种植物防御策略的研究导致了对其进化、机制基础和遗传决定因素的主要认识。本综述旨在总结植物对病原体耐受性的进化原因和后果的现有理论和实验证据，以及对耐受性的遗传决定因素和机制的现有知识。我们的综述表明：（i）在植物-病原体系统中，抗性和耐受性通常共存，即不是相互排斥的；（ii）无论考虑哪种病原体，都有大量耐受性多态性的证据；（iii）耐受性是减少感染宿主受损的有效策略；（iv）没有证据表明耐受性会导致病原体繁殖增加。综上所述，本文讨论的工作表明，在决定植物-病原体相互作用的动态方面，耐受性可能与抗性一样重要。本文还概述了植物对病原体耐受性的几个仍不清楚的方面，这些方面应该在未来进行探索。
