Localization of DIR1 at the tissue, cellular and subcellular levels during Systemic Acquired Resistance in Arabidopsisusing DIR1:GUS and DIR1:EGFP reporters

Champigny, Marc J.; Shearer, Heather; Mohammad, Asif; Haines, Karen; Neumann, Melody; Thilmony, Roger; He, Sheng Yang; Fobert, Pierre R.; Dengler, Nancy G.; Cameron, Robin K.

doi:10.1186/1471-2229-11-125

Cited by 42 publications

(37 citation statements)

References 79 publications

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“…1e), as previously reported 12,34,35 . AZI1:GFP was present in the microsomal and chloroplast fractions, but was not detected in soluble and apoplastic fractions (Fig.…”

Section: Resultssupporting

confidence: 81%

“…To obtain apoplast extracts (intercellular washing fluid) 34 from N. benthamiana: fully expanded leaves of 4-week-old plants infiltrated with Agrobacterium harbouring the different constructs were vacuum infiltrated with sterile distilled water and leaf surfaces dried with absorbent paper before collection of the intercellular washing fluid. To collect the intercellular washing fluid, leaves were centrifuged in swinging buckets at 300 g for 15 min at 4°C.…”

Section: Methodsmentioning

confidence: 99%

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Arabidopsis AZI1 family proteins mediate signal mobilization for systemic defence priming

et al. 2015

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Priming is a major mechanism behind the immunological 'memory' observed during two key plant systemic defences: systemic acquired resistance (SAR) and induced systemic resistance (ISR). Lipid-derived azelaic acid (AZA) is a mobile priming signal. Here, we show that the lipid transfer protein (LTP)-like AZI1 and its closest paralog EARLI1 are necessary for SAR, ISR and the systemic movement and uptake of AZA in Arabidopsis. Imaging and fractionation studies indicate that AZI1 and EARLI1 localize to expected places for lipid exchange/movement to occur. These are the ER/plasmodesmata, chloroplast outer envelopes and membrane contact sites between them. Furthermore, these LTP-like proteins form complexes and act at the site of SAR establishment. The plastid targeting of AZI1 and AZI1 paralogs occurs through a mechanism that may enable/facilitate their roles in signal mobilization.

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“…1e), as previously reported 12,34,35 . AZI1:GFP was present in the microsomal and chloroplast fractions, but was not detected in soluble and apoplastic fractions (Fig.…”

Section: Resultssupporting

confidence: 81%

Section: Methodsmentioning

confidence: 99%

Arabidopsis AZI1 family proteins mediate signal mobilization for systemic defence priming

et al. 2015

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“…Previously we hypothesized that DIR1 moves to distant tissues during SAR (Maldonado et al, 2002) and recently demonstrated that DIR1 is well situated to participate in long distance signaling as it is expressed in companion cells and sieve elements (Champigny et al, 2011). Numerous reviews (Durrant and Dong, 2004; Parker, 2009; Dempsey and Klessig, 2012) present models in which DIR1 translocates to distant tissues during SAR.…”

Section: Introductionmentioning

confidence: 99%

“…Expression and localization of DIR1 using DIR1pro:GUS and DIR1 pro:DIR1-GUS fusion lines (Champigny et al, 2011) demonstrated that DIR1 is expressed in seedlings and flowers, and ubiquitously in untreated or mock-inoculated mature leaf cells including phloem sieve elements and companion cells. Intercellular washing fluid (IWF) experiments and subcellular localization of transiently expressed DIR1:EGFP in tobacco indicated that DIR1's ER signal sequence targets it for secretion to the cell wall.…”

Section: Introductionmentioning

confidence: 99%

“…Intercellular washing fluid (IWF) experiments and subcellular localization of transiently expressed DIR1:EGFP in tobacco indicated that DIR1's ER signal sequence targets it for secretion to the cell wall. Interestingly, a transgenic line expressing DIR1 without its signal sequence in which DIR1 accumulates in the cytosol rescued the dir1-1 SAR defect, suggesting that a cytosolic pool of DIR1 is important for SAR (Champigny et al, 2011). …”

Section: Introductionmentioning

confidence: 99%

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Long distance movement of DIR1 and investigation of the role of DIR1-like during systemic acquired resistance in Arabidopsis

Champigny¹,

Isaacs²,

Carella³

et al. 2013

Front. Plant Sci.

106

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DIR1 is a lipid transfer protein (LTP) postulated to complex with and/or chaperone a signal(s) to distant leaves during Systemic Acquired Resistance (SAR) in Arabidopsis. DIR1 was detected in phloem sap-enriched petiole exudates collected from wild-type leaves induced for SAR, suggesting that DIR1 gains access to the phloem for movement from the induced leaf. Occasionally the defective in induced resistance1 (dir1-1) mutant displayed a partially SAR-competent phenotype and a DIR1-sized band in protein gel blots was detected in dir1-1 exudates suggesting that a highly similar protein, DIR1-like (At5g48490), may contribute to SAR. Recombinant protein studies demonstrated that DIR1 polyclonal antibodies recognize DIR1 and DIR1-like. Homology modeling of DIR1-like using the DIR1-phospholipid crystal structure as template, provides clues as to why the dir1-1 mutant is rarely SAR-competent. The contribution of DIR1 and DIR1-like during SAR was examined using an Agrobacterium-mediated transient expression-SAR assay and an estrogen-inducible DIR1-EGFP/dir1-1 line. We provide evidence that upon SAR induction, DIR1 moves down the leaf petiole to distant leaves. Our data also suggests that DIR1-like displays a reduced capacity to move to distant leaves during SAR and this may explain why dir1-1 is occasionally SAR-competent.

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Induced Disease Resistance

Pieterse

Wees

2014

Principles of Plant-Microbe Interactions

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During the co-evolutionary arms race between plants and pathogens, plants evolved a sophisticated defense system to ward off their enemies. In this plant immune system, plant receptor proteins recognize non-self molecules of microbial origin, which leads to the activation of a basal level of disease resistance. The onset of these local plant immune reactions often triggers a systemic acquired resistance (SAR) in tissues distal from the site of infection. Beneficial microbes in the rhizosphere microbiome stimulate a phenotypically similar induced systemic resistance (ISR) that, like SAR, is effective against a broad spectrum of pathogens. There are differences and similarities in the SAR and ISR signaling pathways. The plant defense hormone salicylic acid is a major regulator of SAR, whereas jasmonic acid and ethylene play important roles in ISR. Priming of systemic tissue to express an accelerated defense response upon attack by a pathogen is a common phenomenon in both SAR and ISR. This chapter will outline the current concept of the plant immune system, with special emphasis on mechanisms of systemically induced disease resistance and priming for enhanced defense.

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Localization of DIR1 at the tissue, cellular and subcellular levels during Systemic Acquired Resistance in Arabidopsisusing DIR1:GUS and DIR1:EGFP reporters

Cited by 42 publications

References 79 publications

Arabidopsis AZI1 family proteins mediate signal mobilization for systemic defence priming

Arabidopsis AZI1 family proteins mediate signal mobilization for systemic defence priming

Long distance movement of DIR1 and investigation of the role of DIR1-like during systemic acquired resistance in Arabidopsis

Induced Disease Resistance

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