| 1. |
- Fahlberg, Per, et al.
(författare)
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Involvement of lipid transfer proteins in resistance against a non-host powdery mildew in Arabidopsis thaliana
- 2019
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Ingår i: Molecular Plant Pathology. - : Wiley. - 1464-6722 .- 1364-3703. ; 20:1, s. 69-77
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Tidskriftsartikel (refereegranskat)abstract
- Non-specific lipid transfer proteins (LTPs) are involved in the transport of lipophilic compounds to the cuticular surface in epidermal cells and in the defence against pathogens. The role of glycophosphatidylinositol (GPI)-anchored LTPs (LTPGs) in resistance against non-host mildews in Arabidopsis thaliana was investigated using reverse genetics. Loss of either LTPG1, LTPG2, LTPG5 or LTPG6 increased the susceptibility to penetration of the epidermal cell wall by Blumeria graminis f. sp. hordei (Bgh). However, no impact on pre-penetration defence against another non-host mildew, Erysiphe pisi (Ep), was observed. LTPG1 was localized to papillae at the sites of Bgh penetration. This study shows that, in addition to the previously known functions, LTPGs contribute to pre-invasive defence against certain non-host powdery mildew pathogens.
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| 2. |
- Johansson, Oskar, et al.
(författare)
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Role of the penetration-resistance genes PEN1, PEN2 and PEN3 in the hypersensitive response and race-specific resistance in Arabidopsis thaliana
- 2014
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Ingår i: Plant Journal. - : Wiley. - 0960-7412. ; 79:3, s. 466-476
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Tidskriftsartikel (refereegranskat)abstract
- Plants are highly capable of recognizing and defending themselves against invading microbes. Adapted plant pathogens secrete effector molecules to suppress the host's immune system. These molecules may be recognized by host-encoded resistance proteins, which then trigger defense in the form of the hypersensitive response (HR) leading to programmed cell death of the host tissue at the infection site. The three proteins PEN1, PEN2 and PEN3 have been found to act as central components in cell wall-based defense against the non-adapted powdery mildew Blumeria graminis fsp. hordei (Bgh). We found that loss of function mutations in any of the three PEN genes cause decreased hypersensitive cell death triggered by recognition of effectors from oomycete and bacterial pathogens in Arabidopsis. There were considerable additive effects of the mutations. The HR induced by recognition of AvrRpm1 was almost completely abolished in the pen2 pen3 and pen1 pen3 double mutants and the loss of cell death could be linked to indole glucosinolate breakdown products. However, the loss of the HR in pen double mutants did not affect the plants' ability to restrict bacterial growth, whereas resistance to avirulent isolates of the oomycete Hyaloperonospora arabidopsidis was strongly compromised. In contrast, the double and triple mutants demonstrated varying degrees of run-away cell death in response to Bgh. Taken together, our results indicate that the three genes PEN1, PEN2 and PEN3 extend in functionality beyond their previously recognized functions in cell wall-based defense against non-host pathogens.
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| 3. |
- Pinosa, Francesco, et al.
(författare)
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Arabidopsis Phospholipase D delta Is Involved in Basal Defense and Nonhost Resistance to Powdery Mildew Fungi
- 2013
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 163:2, s. 896-906
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Tidskriftsartikel (refereegranskat)abstract
- Plants have evolved a complex array of defensive responses against pathogenic microorganisms. Recognition of microbes initiates signaling cascades that activate plant defenses. The membrane lipid phosphatidic acid, produced by phospholipase D (PLD), has been shown to take part in both abiotic and biotic stress signaling. In this study, the involvement of PLD in the interaction between Arabidopsis (Arabidopsis thaliana) and the barley powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) was investigated. This nonadapted pathogen is normally resisted by a cell wall-based defense, which stops the fungal hyphae from penetrating the epidermal cell wall. Chemical inhibition of phosphatidic acid production by PLD increased the penetration rate of Bgh spores on wild-type leaves. The analysis of transfer DNA knockout lines for all Arabidopsis PLD genes revealed that PLD delta is involved in penetration resistance against Bgh, and chemical inhibition of PLDs in plants mutated in PLD delta indicated that this isoform alone is involved in Bgh resistance. In addition, we confirmed the involvement of PLD delta in penetration resistance against another nonadapted pea powdery mildew fungus, Erysiphe pisi. A green fluorescent protein fusion of PLD delta localized to the plasma membrane at the Bgh attack site, where it surrounded the cell wall reinforcement. Furthermore, in the pld delta mutant, transcriptional up-regulation of early microbe-associated molecular pattern response genes was delayed after chitin stimulation. In conclusion, we propose that PLD is involved in defense signaling in nonhost resistance against powdery mildew fungi and put PLD delta forward as the main isoform participating in this process.
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