The level of resistance induced in different tomato genotypes after β-CRY treatment correlated with the upregulation of defence genes, but not sterol binding and involved ethylene and jasmonic acid signalling. Elicitins, a family of small proteins secreted by Phytophthora and Pythium spp., are the most well-known microbe-associated molecular patterns of oomycetes, a lineage of fungus-like organisms that include many economically significant crop pathogens. The responses of tomato plants to elicitin INF1 produced by Phytophthora infestans have been studied extensively. Here, we present studies on the responses of three tomato genotypes to β-cryptogein (β-CRY), a potent elicitin secreted by Phytophthora cryptogea that induces hypersensitive response (HR) cell death in tobacco plants and confers greater resistance to oomycete infection than acidic elicitins like INF1. We also studied β-CRY mutants impaired in sterol binding (Val84Phe) and interaction with the binding site on tobacco plasma membrane (Leu41Phe), because sterol binding was suggested to be important in INF1-induced resistance. Treatment with β-CRY or the Val84Phe mutant induced resistance to powdery mildew caused by the pathogen Pseudoidium neolycopersici, but not the HR cell death observed in tobacco and potato plants. The level of resistance induced in different tomato genotypes correlated with the upregulation of defence genes including defensins, β-1,3-glucanases, heveins, chitinases, osmotins, and PR1 proteins. Treatment with the Leu41Phe mutant did not induce this upregulation, suggesting similar elicitin recognition in tomato and tobacco. However, here β-CRY activated ethylene and jasmonic acid signalling, but not salicylic acid signalling, demonstrating that elicitins activate different downstream signalling processes in different plant species. This could potentially be exploited to enhance the resistance of Phytophthora-susceptible crops.

• Klíčová slova
• Defence-related genes, Elicitins, Pseudoidium neolycopersici, Resistance, Signalling, Sterol binding,
• MeSH
• cyklopentany metabolismus   MeSH
• ethyleny metabolismus   MeSH
• fungální proteiny metabolismus   MeSH
• interakce hostitele a patogenu MeSH
• kyselina salicylová metabolismus   MeSH
• listy rostlin metabolismus   mikrobiologie   MeSH
• nemoci rostlin mikrobiologie   MeSH
• oxylipiny metabolismus   MeSH
• peroxid vodíku metabolismus   MeSH
• Phytophthora MeSH
• Pythium MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• signální transdukce * MeSH
• Solanum lycopersicum metabolismus   mikrobiologie   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cryptogein protein, Phytophthora cryptogea MeSH Prohlížeč
• cyklopentany MeSH
• ethylene MeSH Prohlížeč
• ethyleny MeSH
• fungální proteiny MeSH
• jasmonic acid MeSH Prohlížeč
• kyselina salicylová MeSH
• oxylipiny MeSH
• peroxid vodíku MeSH
• reaktivní formy kyslíku MeSH
• regulátory růstu rostlin MeSH

Although plants are exposed to a great number of pathogens, they usually defend themselves by triggering mechanisms able to limit disease development. Alongside signalling events common to most such incompatible interactions, modifications of plasma membrane (PM) physical properties could be new players in the cell transduction cascade. Different pairs of elicitors (cryptogein, oligogalacturonides, and flagellin) and plant cells (tobacco and Arabidopsis) were used to address the issue of possible modifications of plant PM biophysical properties induced by elicitors and their links to other events of the defence signalling cascade. We observed an increase of PM order whatever the elicitor/plant cell pair used, provided that a signalling cascade was induced. Such membrane modification is dependent on the NADPH oxidase-mediated reactive oxygen species production. Moreover, cryptogein, which is the sole elicitor able to trap sterols, is also the only one able to trigger an increase in PM fluidity. The use of cryptogein variants with altered sterol-binding properties confirms the strong correlation between sterol removal from the PM and PM fluidity enhancement. These results propose PM dynamics as a player in early signalling processes triggered by elicitors of plant defence.

• Klíčová slova
• Cryptogein mutants, elicitors, fluidity, membrane order, plant defence, plasma membrane, reactive oxygen species, signalling.,
• MeSH
• Arabidopsis fyziologie   MeSH
• buněčná membrána metabolismus   fyziologie   MeSH
• fluidita membrány fyziologie   MeSH
• fluorescenční mikroskopie MeSH
• fluorescenční spektrometrie MeSH
• konfokální mikroskopie MeSH
• nemoci rostlin MeSH
• odolnost vůči nemocem fyziologie   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• signální transdukce fyziologie   MeSH
• tabák fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• reaktivní formy kyslíku MeSH

Elicitins are a family of small proteins with sterol-binding activity that are secreted by Phytophthora and Pythium sp. classified as oomycete PAMPs. Although α- and β-elicitins bind with the same affinity to one high affinity binding site on the plasma membrane, β-elicitins (possessing 6-7 lysine residues) are generally 50- to 100-fold more active at inducing distal HR and systemic resistance than the α-isoforms (with only 1-3 lysine residues). To examine the role of lysine residues in elicitin biological activity, we employed site-directed mutagenesis to prepare a series of β-elicitin cryptogein variants with mutations on specific lysine residues. In contrast to direct infiltration of protein into leaves, application to the stem revealed a rough correlation between protein's charge and biological activity, resulting in protection against Phytophthora parasitica. A detailed analysis of proteins' movement in plants showed no substantial differences in distribution through phloem indicating differences in consequent apoplastic or symplastic transport. In this process, an important role of homodimer formation together with the ability to form a heterodimer with potential partner represented by endogenous plants LTPs is suggested. Our work demonstrates a key role of selected lysine residues in these interactions and stresses the importance of processes preceding elicitin recognition responsible for induction of distal systemic resistance.

• Klíčová slova
• cryptogein, dimerization, lipid transfer proteins, lysine residues, movement, resistance,
• Publikační typ
• časopisecké články MeSH