Plant Disease and Defence


Pathogens have evolved elaborate mechanisms to invade plant tissues and cause disease. Plants, in turn, respond to pathogen infection by expressing multiple layers of resistance. Once low energy ‘basal’ defences of plant cells have been overcome by pathogens, the plant can employ a more energy costly system of nonself recognition that triggers an ‘acute’ immune response. The survival of plants depends on their ability to fine‐tune defence responses to the type of pathogen they encounter.

Keywords: microbial pathogen; plant cell death; disease resistance; secondary metabolites; defence signalling

Figure 1.

Sizes and shapes of different pathogenic microorganisms and nematodes in relation to the plant cell.

Figure 2.

Leaf cross‐section showing intercellular bacteria (Ba) and biotrophic (BT) or necrotrophic (NT) fungi/oomycetes. HA: Haustorium, HY: Hyphae.

Figure 3.

Evolution of the plant–bacterial pathogen interaction. (a) The plant has evolved receptors to sense pathogen associated molecular patterns (PAMPs) that trigger basal defences. (b)The bacterium injects effector proteins into the plant cell via a type III secretion system (TTSS) to interfere with defence signalling or response. (c)The plant responds to infection by the generation of immune receptors encoding nucleotide‐binding (NB), mitogen‐associated protein kinase (MAPK), leucine‐rich‐repeat (LRR) R‐proteins that recognize effectors and trigger an acute defence response usually involving cell death.

Figure 4.

Plant signal transduction pathways in response to pathogen attack. ROS: reactive oxygen species, ET: ethylene, JA: jasmonic acid, SA: salicylic acid, SAR: systemic acquired resistance.


Further Reading

Alfano JR and Collmer A (2004) Type III secretion system effector proteins: double agents in bacterial disease and plant defense. Annual Review of Phytopathology 42: 385–414.

Chisholm ST, Coaker G, Day B and Staskauricz BJ (2006) Host‐microbe interactions: shaping the evolution of the plant immune response. Cell 124(4): 803–814.

Delledonne M, Polverari A and Irene Murgia (2003) The functions of nitric oxide‐mediated signaling and changes in gene expression during the hypersensitive response. Antioxidants & Redox Signaling 5(1): 33–41.

Garcia‐Brugger A, Lamotte O, Vandelle E et al. (2006) Early signaling events induced by elicitors of plant defenses. Molecular Plant‐Microbe Interactions 19(7): 711–724.

Glazebrook J (2005) Contrasting mechanisms of defense against biotrophic and necrotrophic pathogens. Annual Review of Phytopathology 43: 205–227.

Grant M and Lamb C (2006) Systemic immunity. Current Opinion in Plant Biology 9(4): 414–420.

Nimchuk Z, Eulgem T, Holt BF and Dangl JL (2003) Recognition and response in the plant immune system. Annual Review of Genetics 37: 579–609.

Slusarenko AJ, Fraser RSS and Loon LC (2000) Mechanisms of Resistance to Plant Diseases. Dordrecht, The Netherlands: Kluwer Academic Publishers.

Zipfel C and Felix G (2005) Plants and animals: a different taste for microbes? Current Opinion in Plant Biology 8(4): 353–360.

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How to Cite close
Rietz, Steffen, and Parker, Jane E(Sep 2007) Plant Disease and Defence. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0004036]