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Publikationen - Natur- und Wirkstoffchemie

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Publikation

Westphal, L.; Strehmel, N.; Eschen-Lippold, L.; Bauer, N.; Westermann, B.; Rosahl, S.; Scheel, D.; Lee, J.; pH effects on plant calcium fluxes: lessons from acidification-mediated calcium elevation induced by the γ-glutamyl-leucine dipeptide identified from Phytophthora infestans Sci. Rep. 9, 4733, (2019) DOI: 10.1038/s41598-019-41276-0

Cytosolic Ca2+ ([Ca2+]cyt) elevation is an early signaling response upon exposure to pathogen-derived molecules (so-called microbe-associated molecular patterns, MAMPs) and has been successfully used as a quantitative read-out in genetic screens to identify MAMP receptors or their associated components. Here, we isolated and identified by mass spectrometry the dipeptide γ-Glu-Leu as a component of a Phytophthora infestans mycelium extract that induces [Ca2+]cyt elevation. Treatment of Arabidopsis seedlings with synthetic γ-Glu-Leu revealed stimulatory effects on defense signaling, including a weak enhancement of the expression of some MAMP-inducible genes or affecting the refractory period to a second MAMP elicitation. However, γ-Glu-Leu is not a classical MAMP since pH adjustment abolished these activities and importantly, the observed effects of γ-Glu-Leu could be recapitulated by mimicking extracellular acidification. Thus, although γ-Glu-Leu can act as a direct agonist of calcium sensing receptors in animal systems, the Ca2+-mobilizing activity in plants reported here is due to acidification. Low pH also shapes the Ca2+ signature of well-studied MAMPs (e.g. flg22) or excitatory amino acids such as glutamate. Overall, this work serves as a cautionary reminder that in defense signaling studies where Ca2+ flux measurements are concerned, it is important to monitor and consider the effects of pH.
Publikation

Matern, A.; Böttcher, C.; Eschen-Lippold, L.; Westermann, B.; Smolka, U.; Döll, S.; Trempel, F.; Aryal, B.; Scheel, D.; Geisler, M.; Rosahl, S.; A substrate of the ABC transporter PEN3 stimulates bacterial flagellin (flg22)-induced callose deposition in Arabidopsis thaliana J. Biol. Chem. 294, 6857-6870, (2019) DOI: 10.1074/jbc.RA119.007676

Nonhost resistance of Arabidopsis thaliana against Phytophthora infestans, a filamentous eukaryotic microbe and the causal agent of potato late blight, is based on a multilayered defense system. Arabidopsis thaliana controls pathogen entry through the penetration-resistance genes PEN2 and PEN3, encoding an atypical myrosinase and an ABC transporter, respectively, required for synthesis and export of unknown indole compounds. To identify pathogen-elicited leaf surface metabolites and further unravel nonhost resistance in Arabidopsis, we performed untargeted metabolite profiling by incubating a P. infestans zoospore suspension on leaves of WT or pen3 mutant Arabidopsis plants. Among the plant-secreted metabolites, 4-methoxyindol-3-yl-methanol and S-(4-methoxy-indol-3-yl-methyl) cysteine were detected in spore suspensions recollected from WT plants, but at reduced levels from the pen3 mutant plants. In both whole-cell and microsome-based assays, 4-methoxyindol-3-yl-methanol was transported in a PEN3-dependent manner, suggesting that this compound is a PEN3 substrate. The syntheses of both compounds were dependent on functional PEN2 and phytochelatin synthase 1. None of these compounds inhibited mycelial growth of P. infestans in vitro. Of note, exogenous application of 4-methoxyindol-3-yl methanol slightly elevated cytosolic Ca2+ levels and enhanced callose deposition in hydathodes of seedlings treated with a bacterial pathogen-associated molecular pattern (PAMP), flagellin (flg22). Loss of flg22-induced callose deposition in leaves of pen3 seedlings was partially reverted by the addition of 4-methoxyindol-3-yl methanol. In conclusion, we have identified a specific indole compound that is a substrate for PEN3 and contributes to the plant defense response against microbial pathogens.
Publikation

Landgraf, R.; Smolka, U.; Altmann, S.; Eschen-Lippold, L.; Senning, M.; Sonnewald, S.; Weigel, B.; Frolova, N.; Strehmel, N.; Hause, G.; Scheel, D.; Böttcher, C.; Rosahl, S.; The ABC Transporter ABCG1 Is Required for Suberin Formation in Potato Tuber Periderm Plant Cell 26, 3403-3415, (2014) DOI: 10.1105/tpc.114.124776

The lipid biopolymer suberin plays a major role as a barrier both at plant-environment interfaces and in internal tissues, restricting water and nutrient transport. In potato (Solanum tuberosum), tuber integrity is dependent on suberized periderm. Using microarray analyses, we identified ABCG1, encoding an ABC transporter, as a gene responsive to the pathogen-associated molecular pattern Pep-13. Further analyses revealed that ABCG1 is expressed in roots and tuber periderm, as well as in wounded leaves. Transgenic ABCG1-RNAi potato plants with downregulated expression of ABCG1 display major alterations in both root and tuber morphology, whereas the aerial part of the ABCG1-RNAi plants appear normal. The tuber periderm and root exodermis show reduced suberin staining and disorganized cell layers. Metabolite analyses revealed reduction of esterified suberin components and hyperaccumulation of putative suberin precursors in the tuber periderm of RNA interference plants, suggesting that ABCG1 is required for the export of suberin components.
Publikation

Eschen-Lippold, L.; Rosahl, S.; Westermann, B.; Arnold, N.; Aus Pilzen isolierte Substanz gegen den Erreger der Kraut- und Knollenfäule Kartoffelbau 63, 18-21, (2012)

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Publikation

Eschen-Lippold, L.; Draeger, T.; Teichert, A.; Wessjohann, L.; Westermann, B.; Rosahl, S.; Arnold, N.; Antioomycete Activity of γ-Oxocrotonate Fatty Acids against P. infestans J. Agr. Food Chem. 57, 9607-9612, (2009) DOI: 10.1021/jf902067k

Infections with Phytophthora infestans, the causal agent of potato and tomato late blight disease, are difficult to control and can lead to considerable agricultural losses. Thus, the development of new effective agents against the pathogen is of great interest. In previous work, (E)-4-oxohexadec-2-enoic acid (3) was isolated from Hygrophorus eburneus, which exhibited fungicidal activity against Cladosporium cucumerinum. Here, the inhibitory effect of 3 on P. infestans spore germination and mycelium growth in vitro is demonstrated. The in vivo effect on infections of whole potato plants was investigated by spraying plants with the sodium salt of 3, sodium (2E)-4-oxohexadec-2-enoic acid (4), prior to P. infestans inoculation. Additionally, the influence of 3 on mycelium growth of Colletotrichum coccodes, the causal agent of potato black dot disease, was analyzed. In all approaches, a significant inhibition of pathogen development was achieved. Importantly, the unsaturated fatty acid exerted no toxic effect when sprayed on plants, a prerequisite for its commercial use.
Publikation

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.
Publikation

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.
Publikation

Schmidt, A.; Grimm, R.; Schmidt, J.; Scheel, D.; Strack, D.; Rosahl, S.; Cloning and Expression of a Potato cDNA Encoding Hydroxycinnamoyl-CoA:Tyramine N-(Hydroxycinnamoyl)transferase J. Biol. Chem. 274, 4273-4280, (1999) DOI: 10.1074/jbc.274.7.4273

Hydroxycinnamoyl-CoA:tyramineN-(hydroxycinnamoyl)transferase (THT; EC 2.3.1.110) catalyzes the transfer of hydroxycinnamic acids from the respective CoA esters to tyramine and other amines in the formation ofN-(hydroxycinnamoyl)amines. Expression of THT is induced byPhytophthora infestans, the causative agent of late blight disease in potato. The amino acid sequences of nine endopeptidase LysC-liberated peptides from purified potato THT were determined. Using degenerate primers, a THT-specific fragment was obtained by reverse transcription-polymerase chain reaction, and THT cDNA clones were isolated from a library constructed from RNA of elicitor-treated potato cells. The open reading frame encoding a protein of 248 amino acids was expressed in Escherichia coli. Recombinant THT exhibited a broad substrate specificity, similar to that of native potato THT, accepting cinnamoyl-, 4-coumaroyl-, caffeoyl-, feruloyl- and sinapoyl-CoA as acyl donors and tyramine, octopamine, and noradrenalin as acceptors tested. Elicitor-induced THT transcript accumulation in cultured potato cells peaked 5 h after initiation of treatment, whereas enzyme activity was highest from 5 to 30 h after elicitation. In soil-grown potato plants, THT mRNA was most abundant in roots. Genomic Southern analyses indicate that, in potato, THT is encoded by a multigene family.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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