Salicylic acid-independent plant defence pathways

Pieterse, Corné M. J.; Loon, L.C. van

doi:10.1016/s1360-1385(98)01364-8

Cited by 571 publications

(343 citation statements)

References 56 publications

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“…The accumulation of SA in response to elicitors and pathogen challenge was earlier shown in pine (Davis et al 2002). SA is furthermore known to induce specific sets of PR genes (Pieterse and van Loon 1999) prior to the establishment of systemic acquired resistance (Grant and Lamb 2006). In contrast to the results with Sp-AMP, expression of Pm-AMP1, a homolog in western white pine (Pinus monitcola) that is involved in defence against the blister rust fungus Cronartium ribicola, is induced in healthy foliage 4 days after MeJA treatment (Ekramoddoullah et al 2006).…”

Section: Discussionmentioning

confidence: 76%

Expression and β-glucan binding properties of Scots pine (Pinus sylvestris L.) antimicrobial protein (Sp-AMP)

et al. 2011

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Scots pine (Pinus sylvestris) secretes a number of small, highly-related, disulfide-rich proteins (Sp-AMPs) in response to challenges with fungal pathogens such as Heterobasidion annosum, although their biological role has been unknown. Here, we examined the expression patterns of these genes, as well as the structure and function of the encoded proteins. Northern blots and quantitative real time PCR showed increased levels of expression that are sustained during the interactions of host trees with pathogens, but not non-pathogens, consistent with a function in conifer tree defenses. Furthermore, the genes were up-regulated after treatment with salicylic acid and an ethylene precursor, 1-aminocyclopropane-1-carboxylic-acid, but neither methyl jasmonate nor H 2 O 2 induced expression, indicating that Sp-AMP gene expression is independent of the jasmonic acid signaling pathways. The cDNA encoding one of the proteins was cloned and expressed in Pichia pastoris. The purified protein had antifungal activity against H. annosum, and caused morphological changes in its hyphae and spores. It was directly shown to bind soluble and insoluble β-(1,3)-glucans, specifically and with high affinity. Furthermore, addition of exogenous glucan is linked to higher levels of Sp-AMP expression in the conifer. Homology modeling and sequence comparisons suggest that a conserved patch on the surface of the globular Sp-AMP is a carbohydrate-binding site that can accommodate approximately four sugar units. We conclude that these proteins belong to a new family of antimicrobial proteins that are likely to act by binding the glucans that are a major component of fungal cell walls.

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Section: Discussionmentioning

confidence: 76%

Expression and β-glucan binding properties of Scots pine (Pinus sylvestris L.) antimicrobial protein (Sp-AMP)

et al. 2011

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“…Recent advances in research on plant defense signalling pathways have shown that plants are capable of di erentially activating distinct defense pathways depending on the type of invader encountered [36]. Upon pathogen infection, the production of JA and ethylene is stimulated, leading to the activation of speci®c defense-related genes [4,57].…”

Section: Discussionmentioning

confidence: 99%

Rhizobacteria-mediated induced systemic resistance (ISR) in Arabidopsis requires sensitivity to jasmonate and ethylene but is not accompanied by an increase in their production

Pieterse

Pelt

Ton

et al. 2000

Physiological and Molecular Plant Pathology

221

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Plants develop an enhanced defensive capacity against a broad spectrum of plant pathogens after colonization of the roots by selected strains of nonpathogenic biocontrol bacteria. In Arabidopsis thaliana, this induced systemic resistance (ISR) functions independently of salicylic acid but requires an intact response to the plant hormones jasmonic acid (JA) and ethylene. To further investigate the roles of JA and ethylene in the ISR signalling pathway, the levels of these signalling molecules were determined in A. thaliana upon induction of ISR by Pseudomonas¯uorescens WCS417r and subsequent challenge inoculation with Pseudomonas syringae pv. tomato DC3000. Upon treatment of the roots with ISR-inducing WCS417r bacteria, neither the JA content, nor the level of ethylene evolution was altered in systemically resistant leaves. In®ltration of leaves with WCS417r triggered the JA-and ethylene-dependent ISR pathway, but did not cause local changes in the production of either of these signalling molecules. These results indicate that rhizobacteria-mediated ISR is not based on the induction of changes in the biosynthesis of either JA or ethylene. However, in ISR-expressing plants the capacity to convert 1-aminocyclopropane-1-carboxylate (ACC) to ethylene was signi®cantly enhanced, providing a greater potential to produce ethylene upon pathogen attack.*

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“…These include systemic acquired resistance (SAR), which is triggered by necrotizing pathogens [1]; induced systemic resistance (ISR), which is activated upon colonization of roots by selected strains of non-pathogenic rhizobacteria [2]; and woundinduced defense, which is typically elicited upon tissue damage such as that caused by feeding insects ( [3]; Figure 1). Induced defense responses are regulated by a network of interconnecting signal transduction pathways in which the hormonal signals salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) play a major role [4][5][6], and other hormones such as brassinosteroids and abscisic acid can also be involved [7][8][9].…”

Section: Introductionmentioning

confidence: 99%