J.P. Wubben

Bio: J.P. Wubben is an academic researcher. The author has contributed to research in topics: Gene & Hypersensitive response. The author has an hindex of 6, co-authored 9 publications receiving 257 citations.

Expression and localization of two in planta induced extracellular proteins of the fungal tomato pathogen Cladosporium fulvum.

Abstract: Expression of two in planta induced genes of the biotrophic fungal tomato pathogen Cladosporium fulvum and accumulation of their products, extracellular proteins (ECPs), were studied in time and space during pathogenesis. Immunogold localization revealed that proteins ECP1 and ECP2 accumulated abundantly in extracellular material in the vicinity of fungal and host cell walls. Expression of the genes encoding ECP1 and ECP2 was studied in transformants carrying the reporter gene Gus fused to promoter sequences of the ecp genes. In germinated conidia on the leaf surface no expression of gene ecp1 and only low expression of gene ecp2 could be detected. Expression of both ecp1 and ecp2 was strongly induced during colonization of the intercellular space between tomato mesophyll cells. The highest expression was observed in hyphae growing near vascular tissue. Expression levels were low in newly formed conidia on leaves. Possible functions of ECP1 and ECP2 for C. fulvum during pathogenesis are discussed.

Molecular Characterization of the Interaction Between the Fungal Pathogen Cladosporium Fulvum and Tomato

Abstract: The fungus Cladosprium fulvum is a biotrophic leaf pathogen of tomato. The fungus develops in the intercellular space without forming specialized feeding structures and does not affect the leaf tissue. The outcome of the C. fulvum-tomato interaction can be described by the gene-for-gene model. Failure of infection is expressed by a hypersensitive response. Two fungal proteins, ECP1 and ECP2, have been isolated and their corresponding genes have been cloned. In a compatible interaction including many physiological races ECP1 and ECP2 are highly produced and a role in pathogenicity is suggestive. The ecp1 gene shows some homology with tumor necrosis factor receptors (TNFRs) while the ecp2 gene shows no homology with sequences known in data bases. However, disruption of one of the two genes showed no reduced pathogenicity of the fungus. Two race-specific elicitors, AVR4 and AVR9, have been isolated and their corresponding genes have been cloned. The avirulence genes Avr4 and Avr9 are only present in C. fulvum avirulent on Cf-4 and Cf-9 cultivars, respectively. The expression of these two genes is, like the expression of the ecp genes, highly induced when the fungus grows in planta. Disruption of the Avr9 gene in wild type avirulent races leads to virulence on tomato genotypes carrying the complementary resistance gene Cf-9. A single base-pair change in the avirulence gene Avr4 leads to virulence on tomato genotypes carrying the Cf-4 resistance gene. Isolation, characterization and possible function of ECP1, ECP2, AVR4, and AVR9 will be discussed.

Accumulation of pathogenesis-related proteins in the epidermis of tomato leaves infected by Cladosporium fulvum

Abstract: Upon infection byCladosporium fulvum, tomato plants start to produce pathogenesis-related (PR) proteins. The PR proteins 1,3-β-glucanase, chitinase, and PR-1b accumulated near the stomata in the lower epidermis ofC. fulvum-inoculated tomato leaves as could be determined by immunolocalization with polyclonal antibodies. However, no differences in accumulation of PR proteins between a compatible and an incompatible interaction were found. Results obtained from enzyme activity measurements of 1,3-β-glucanase and chitinase on similar leaf material as used for the immunolocalization did not fully reflect the immunolocalization data. The antibodies possibly detect only the extracellular but not the intracellular enzymes. The accumulation of PR proteins near the stomata might be part of a general defence response of plants against pathogens and potential pathogens.

A LysM Receptor-Like Kinase Plays a Critical Role in Chitin Signaling and Fungal Resistance in Arabidopsis

Abstract: Chitin, a polymer of N -acetyl-d-glucosamine, is found in fungal cell walls but not in plants. Plant cells can perceive chitin fragments (chitooligosaccharides) leading to gene induction and defense responses. We identified a LysM receptor-like protein (LysM RLK1) required for chitin signaling in Arabidopsis thaliana . The mutation in this gene blocked the induction of almost all chitooligosaccharide-responsive genes and led to more susceptibility to fungal pathogens but had no effect on infection by a bacterial pathogen. Additionally, exogenously applied chitooligosaccharides enhanced resistance against both fungal and bacterial pathogens in the wild-type plants but not in the mutant. Together, our data indicate that LysM RLK1 is essential for chitin signaling in plants (likely as part of the receptor complex) and is involved in chitin-mediated plant innate immunity. The LysM RLK1-mediated chitin signaling pathway is unique, but it may share a conserved downstream pathway with the FLS2/flagellin- and EFR/EF-Tu–mediated signaling pathways. Additionally, our work suggests a possible evolutionary relationship between the chitin and Nod factor perception mechanisms due to the similarities between their potential receptors and between the signal molecules perceived by them.

Cellular Response of Pea Plants to Cadmium Toxicity: Cross Talk between Reactive Oxygen Species, Nitric Oxide, and Calcium

Abstract: Cadmium (Cd) toxicity has been widely studied in different plant species; however, the mechanism involved in its toxicity as well as the cell response against the metal have not been well established. In this work, using pea (Pisum sativum) plants, we studied the effect of Cd on antioxidants, reactive oxygen species (ROS), and nitric oxide (NO) metabolism of leaves using different cellular, molecular, and biochemical approaches. The growth of pea plants with 50 μm CdCl2 affected differentially the expression of superoxide dismutase (SOD) isozymes at both transcriptional and posttranscriptional levels, giving rise to a SOD activity reduction. The copper/zinc-SOD down-regulation was apparently due to the calcium (Ca) deficiency induced by the heavy metal. In these circumstances, the overproduction of the ROS hydrogen peroxide and superoxide could be observed in vivo by confocal laser microscopy, mainly associated with vascular tissue, epidermis, and mesophyll cells, and the production of superoxide radicals was prevented by exogenous Ca. On the other hand, the NO synthase-dependent NO production was strongly depressed by Cd, and treatment with Ca prevented this effect. Under these conditions, the pathogen-related proteins PrP4A and chitinase and the heat shock protein 71.2, were up-regulated, probably to protect cells against damages induced by Cd. The regulation of these proteins could be mediated by jasmonic acid and ethylene, whose contents increased by Cd treatment. A model is proposed for the cellular response to long-term Cd exposure consisting of cross talk between Ca, ROS, and NO.

The Pto kinase conferring resistance to tomato bacterial speck disease interacts with proteins that bind a cis-element of pathogenesis-related genes

Abstract: In tomato, the Pto kinase confers resistance to bacterial speck disease by recognizing the expression of a corresponding avirulence gene, avrPto, in the pathogen Pseudomonas syringae pv. tomato. Using the yeast two-hybrid system, we have identified three genes, Pti4, Pti5 and Pti6, that encode proteins that physically interact with the Pto kinase. Pti4/5/6 each encode a protein with characteristics that are typical of transcription factors and are similar to the tobacco ethylene-responsive element-binding proteins (EREBPs). Using a gel mobility-shift assay, we demonstrate that, similarly to EREBPs, Pti4/5/6 specifically recognize and bind to a DNA sequence that is present in the promoter region of a large number of genes encoding ‘pathogenesis-related’ (PR) proteins. Expression of several PR genes and a tobacco EREBP gene is specifically enhanced upon Pto–avrPto recognition in tobacco. These observations establish a direct connection between a disease resistance gene and the specific activation of plant defense genes.

Pathogenesis-related proteins in plants

Abstract: Occurrence and Properties of Plant Pathogenesis Related Proteins-Professor Van Loon PR-1, a Group of Plant Proteins Induced upon Pathogen Infection- Dr. Annemarie Buchel, and Professor Huub Linthorst Functions and Regulation of Plant b-1, 3-glucanases (PR-2)-Dr. Gerhard Leubner Metzger, and Professor Dr. Frederick Meins, Jr. Plant Chitinases (PR-3, PR-4, PR-8, PR-11)-Professor Dr. Jean-Marc Neuhaus The PR-5 Family Thaumatin-Like Proteins-Dr. R. Velazhahan, Dr. S. K. Datta, and Professor Muthukrishnan The PR-6 Family Proteinase Inhibitors in Plant-Microbe Interactions-Dr. Thierry Heitz, Dr. Pierett Geoffroy, Dr. Bernard Fritig, and Dr. Michael Legrand The Response of Plant Cell Wall Hydroxyproline-Rich Glycoproteins to Microbial Pathogens and their Elicitors-Dr. Marie Therese Esquerre- Tugaye, Dr. C. Campargue, and Dr. D. Mazau Induction of Peroxidase During Defense Against Pathogens-Dr. C. M. Chittoor, Professor J. E. Leach, and Professor F. F. White Signal Transduction and Pathogen-induced PR Gene Expression-Jian-Min Zhou The Role of Thionins in the Resistance of Plants-Dr. Holger Bohlmann Ribosome Inactivating Proteins: Structure, Function, and Engineering-Dr. Anders B. Jensen, Dr. Robert Leach, Dr. Bushra Chaudhury, and Professor John Mundy Plant Defensins-Dr. Alexandre de Silva Conceicao, and Dr. Willem Broekaert Expression and Function of PR-Protein Genes in Transgenic Plants-Dr. Karabi Datta, Professor Subbaratnam Muthukrishnan, and Dr. Swapan K. Datta