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Publications - Stress and Develop Biology

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Publications

Kopischke, M.; Westphal, L.; Schneeberger, K.; Clark, R.; Ossowski, S.; Wewer, V.; Fuchs, R.; Landtag, J.; Hause, G.; Dörmann, P.; Lipka, V.; Weigel, D.; Schulze-Lefert, P.; Scheel, D.; Rosahl, S.; Impaired sterol ester synthesis alters the response of Arabidopsis thaliana to Phytophthora infestans Plant J. 73, 456-468, (2013) DOI: 10.1111/tpj.12046

Non‐host resistance of Arabidopsis thaliana against Phytophthora infestans, the causal agent of late blight disease of potato, depends on efficient extracellular pre‐ and post‐invasive resistance responses. Pre‐invasive resistance against P. infestans requires the myrosinase PEN2. To identify additional genes involved in non‐host resistance to P. infestans, a genetic screen was performed by re‐mutagenesis of pen2 plants. Fourteen independent mutants were isolated that displayed an enhanced response to Phytophthora (erp) phenotype. Upon inoculation with P. infestans, two mutants, pen2‐1 erp1‐3 and pen2‐1 erp1‐4, showed an enhanced rate of mesophyll cell death and produced excessive callose deposits in the mesophyll cell layer. ERP1 encodes a phospholipid:sterol acyltransferase (PSAT1) that catalyzes the formation of sterol esters. Consistent with this, the tested T‐DNA insertion lines of PSAT1 are phenocopies of erp1 plants. Sterol ester levels are highly reduced in all erp1/psat1 mutants, whereas sterol glycoside levels are increased twofold. Excessive callose deposition occurred independently of PMR4/GSL5 activity, a known pathogen‐inducible callose synthase. A similar formation of aberrant callose deposits was triggered by the inoculation of erp1psat1 plants with powdery mildew. These results suggest a role for sterol conjugates in cell non‐autonomous defense responses against invasive filamentous pathogens.
Publications

Lipka, V.; Dittgen, J.; Bednarek, P.; Bhat, R.; Wiermer, M.; Stein, M.; Landtag, J.; Brandt, W.; Rosahl, S.; Scheel, D.; Llorente, F.; Molina, A.; Parker, J.; Somerville, S.; Schulze-Lefert, P.; Pre- and Postinvasion Defenses Both Contribute to Nonhost Resistance in Arabidopsis Science 310, 1180-1183, (2005) DOI: 10.1126/science.1119409

Nonhost resistance describes the immunity of an entire plant species against nonadapted pathogen species. We report that Arabidopsis PEN2 restricts pathogen entry of two ascomycete powdery mildew fungi that in nature colonize grass and pea species. The PEN2 glycosyl hydrolase localizes to peroxisomes and acts as a component of an inducible preinvasion resistance mechanism. Postinvasion fungal growth is blocked by a separate resistance layer requiring the EDS1-PAD4-SAG101 signaling complex, which is known to function in basal and resistance (R) gene–triggered immunity. Concurrent impairment of pre- and postinvasion resistance renders Arabidopsis a host for both nonadapted fungi.
Publications

Landtag, J.; Baumert, A.; Degenkolb, T.; Schmidt, J.; Wray, V.; Scheel, D.; Strack, D.; Rosahl, S.; Accumulation of tyrosol glucoside in transgenic potato plants expressing a parsley tyrosine decarboxylase Phytochemistry 60, 683-689, (2002) DOI: 10.1016/S0031-9422(02)00161-9

As part of the response to pathogen infection, potato plants accumulate soluble and cell wall-bound phenolics such as hydroxycinnamic acid tyramine amides. Since incorporation of these compounds into the cell wall leads to a fortified barrier against pathogens, raising the amounts of hydroxycinnamic acid tyramine amides might positively affect the resistance response. To this end, we set out to increase the amount of tyramine, one of the substrates of the hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)-transferase reaction, by placing a cDNA encoding a pathogen-induced tyrosine decarboxylase from parsley under the control of the 35S promoter and introducing the construct into potato plants via Agrobacterium tumefaciens-mediated transformation. While no alterations were observed in the pattern and quantity of cell wall-bound phenolic compounds in transgenic plants, the soluble fraction contained several new compounds. The major one was isolated and identified as tyrosol glucoside by liquid chromatography–electrospray ionization–high resolution mass spectrometry and NMR analyses. Our results indicate that expression of a tyrosine decarboxylase in potato does not channel tyramine into the hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)-transferase reaction but rather unexpectedly, into a different pathway leading to the formation of a potential storage compound.Expression of a parsley tyrosine decarboxylase in potato unexpectedly channels tyramine into a pathway leading to the formation of tyrosol glucoside.
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