MAIN CONCLUSION: 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.

• 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

Cryptogein is a proteinaceous elicitor secreted by Phytophthora cryptogea that can induce resistance to P. parasitica in tobacco plants. On the basis of previous computer modelling experiments, by site-directed mutagenesis a series of cryptogein variants was prepared with altered abilities to bind sterols, phospholipids or both. The sterol binding and phospholipid transfer activities corresponded well with the previously reported structural data. Induction of the synthesis of reactive oxygen species (ROS) in tobacco cells in suspension and proteomic analysis of intercellular fluid changes in tobacco leaves triggered by these mutant proteins were not proportional to their ability to bind or transfer sterols and phospholipids. However, changes in the intercellular proteome corresponded to transcription levels of defence genes and resistance to P. parasitica and structure-prediction of mutants did not reveal any significant changes in protein structure. These results suggest, contrary to previous proposals, that the sterol-binding ability of cryptogein and its mutants, and the associated conformational change in the ω-loop, might not be principal factors in either ROS production or resistance induction. Nevertheless, the results support the importance of the ω-loop for the interaction of the protein with the high affinity binding site on the plasma membrane.

• MeSH
• fosfolipidy metabolismus   MeSH
• fungální proteiny genetika   metabolismus   MeSH
• imunita rostlin imunologie   MeSH
• kyselina chlorogenová analýza   MeSH
• listy rostlin genetika   imunologie   parazitologie   fyziologie   MeSH
• mutace MeSH
• nemoci rostlin imunologie   parazitologie   MeSH
• Phytophthora genetika   metabolismus   patogenita   MeSH
• proteiny genetika   metabolismus   MeSH
• proteomika metody   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• rekombinantní proteiny MeSH
• seskviterpeny analýza   MeSH
• steroly metabolismus   MeSH
• tabák genetika   imunologie   parazitologie   fyziologie   MeSH
• vazba proteinů MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Background and Aims: Current strategies for increased crop protection of susceptible tomato plants against pathogen infections include treatment with synthetic chemicals, application of natural pathogen-derived compounds or transfer of resistance genes from wild tomato species within breeding programmes. In this study, a series of 45 genes potentially involved in defence mechanisms was retrieved from the genome sequence of inbred reference tomato cultivar Solanum lycopersicum 'Heinz 1706'. The aim of the study was to analyse expression of these selected genes in wild and cultivated tomato plants contrasting in resistance to the biotrophic pathogen Oidium neolycopersici , the causative agent of powdery mildew. Plants were treated either solely with potential resistance inducers or by inducers together with the pathogen. Methods: The resistance against O. neolycopersici infection as well as RT-PCR-based analysis of gene expression in response to the oomycete elicitor oligandrin and chemical agent β-aminobutyric acid (BABA) were investigated in the highly susceptible domesticated inbred genotype Solanum lycopersicum 'Amateur' and resistant wild genotype Solanum habrochaites . Key Results: Differences in basal expression levels of defensins, germins, β-1,3-glucanases, heveins, chitinases, osmotins and PR1 proteins in non-infected and non-elicited plants were observed between the highly resistant and susceptible genotypes. Moreover, these defence genes showed an extensive up-regulation following O. neolycopersici infection in both genotypes. Application of BABA and elicitin induced expression of multiple defence-related transcripts and, through different mechanisms, enhanced resistance against powdery mildew in the susceptible tomato genotype. Conclusions: The results indicate that non-specific resistance in the resistant genotype S. habrochaites resulted from high basal levels of transcripts with proven roles in defence processes. In the susceptible genotype S. lycopersicum 'Amateur', oligandrin- and BABA-induced resistance involved different signalling pathways, with BABA-treated leaves displaying direct activation of the ethylene-dependent signalling pathway, in contrast to previously reported jasmonic acid-mediated signalling for elicitins.

• MeSH
• aminobutyráty farmakologie   MeSH
• Ascomycota fyziologie   MeSH
• kvantitativní polymerázová řetězová reakce MeSH
• nemoci rostlin imunologie   mikrobiologie   MeSH
• odolnost vůči nemocem MeSH
• regulace genové exprese u rostlin * MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• sekvenční analýza DNA MeSH
• seskviterpeny farmakologie   MeSH
• Solanum lycopersicum genetika   imunologie   mikrobiologie   MeSH
• Solanum genetika   imunologie   mikrobiologie   MeSH
• upregulace MeSH
• Publikační typ
• časopisecké články MeSH