Use of a secretion trap screen in pepper following Phytophthora capsici infection reveals novel functions of secreted plant proteins in modulating cell death.

Department of Plant Science, Seoul National University, Seoul, Republic of Korea.
Molecular Plant-Microbe Interactions (Impact Factor: 4.46). 06/2011; 24(6):671-84. DOI: 10.1094/MPMI-08-10-0183
Source: PubMed

ABSTRACT In plants, the primary defense against pathogens is mostly inducible and associated with cell wall modification and defense-related gene expression, including many secreted proteins. To study the role of secreted proteins, a yeast-based signal-sequence trap screening was conducted with the RNA from Phytophthora capsici-inoculated root of Capsicum annuum 'Criollo de Morelos 334' (CM334). In total, 101 Capsicum annuum secretome (CaS) clones were isolated and identified, of which 92 were predicted to have a secretory signal sequence at their N-terminus. To identify differences in expressed CaS genes between resistant and susceptible cultivars of pepper, reverse Northern blots and real-time reverse-transcription polymerase chain reaction were performed with RNA samples isolated at different time points following P. capsici inoculation. In an attempt to assign biological functions to CaS genes, we performed in planta knock-down assays using the Tobacco rattle virus-based gene-silencing method. Silencing of eight CaS genes in pepper resulted in suppression of the cell death induced by the non-host bacterial pathogen (Pseudomonas syringae pv. tomato T1). Three CaS genes induced phenotypic abnormalities in silenced plants and one, CaS259 (PR4-l), caused both cell death suppression and perturbed phenotypes. These results provide evidence that the CaS genes may play important roles in pathogen defense as well as developmental processes.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Pepper (Capsicum annuum L.) provides a good experimental system for studying the molecular and functional genomics underlying the ability of plants to defend themselves against microbial pathogens. Cell death is a genetically programmed response that requires specific host cellular factors. Hypersensitive response (HR) is defined as rapid cell death in response to a pathogen attack. Pepper plants respond to pathogen attacks by activating genetically controlled HR- or disease-associated cell death. HR cell death, specifically in incompatible interactions between pepper and Xanthomonas campestris pv. vesicatoria, is mediated by the molecular genetics and biochemical machinery that underlie pathogen-induced cell death in plants. Gene expression profiles during the HR-like cell death response, virus-induced gene silencing and transient and transgenic overexpression approaches are used to isolate and identify HR- or disease-associated cell death genes in pepper plants. Reactive oxygen species, nitric oxide, cytosolic calcium ion and defense-related hormones such as salicylic acid, jasmonic acid, ethylene and abscisic acid are involved in the execution of pathogen-induced cell death in plants. In this review, we summarize recent molecular and cellular studies of the pepper cell death-mediated defense response, highlighting the signaling events of cell death in disease-resistant pepper plants. Comprehensive knowledge and understanding of the cellular functions of pepper cell death response genes will aid the development of novel practical approaches to enhance disease resistance in pepper, thereby helping to secure the future supply of safe and nutritious pepper plants worldwide.
    Planta 09/2014; 241(1). DOI:10.1007/s00425-014-2171-6 · 3.38 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Plants recognize certain microbial compounds as elicitors of their active defense mechanisms. In the present study, NUBS-4190, a synthetic bis-aryl-methanone compound elicited NO and ROS generation in potato suspension cultured cells and intact potato leaves. Hypersensitive cell death was found in these cultured cells and in potato leaves without the accumulation of phytoalexins in the tubers. Defense-related genes such as StrbohB, StrbohC, StNR1, StNR5, Sthsr203J and StPR1 were expressed in potato suspension cultured cells treated with NUBS-4190. Resistance against Phytophthora infestans also increased in NUBS-4190-treated potato leaves.
    Journal of General Plant Pathology 01/2014; 80(1). DOI:10.1007/s10327-013-0493-z · 0.71 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this study, we investigated the activities of β-1,3-glucanase and peroxidase enzymes in the leaves of pepper cultivar A3 infected with the incompatible strain PC and the compatible strain HX-9 of Phytophthora capsici. The activities of β-1,3-glucanase and peroxidase enzymes substantially increased in the incompatible interactions compared to the compatible interactions. We also analysed the expression patterns of four defence-related genes, including CABPR1, CABGLU, CAPO1 and CaRGA1, in the leaves and roots of pepper inoculated with different strains of P. capsici. All gene expression levels were higher in the leaves than in the roots. Markedly different expression patterns were observed between incompatible and compatible host-pathogen interactions. In the incompatible interactions, the expression levels of CABPR1, CABGLU and CAPO1 genes in leaves increased by a maximum of 17.2-, 13.2- and 20.5-fold at 24, 12 and 12 h, respectively, whereas the CaRGA1 gene expression level increased to a lesser degree, 6.0-fold at 24 h. However, in the compatible interactions, the expression levels of the four defence-related genes increased by a maximum of 11.2-, 8.6-, 7.9- and 2.0-fold at 48, 24, 48 and 72 h, respectively. Compared to the leaves, the expression levels of the four defence-related genes were much lower in the roots. The highest levels of mRNA were those of the CABPR1 gene, which increased 5.1-fold at 24 h in the incompatible and 3.2-fold at 48 h in the compatible interactions. The other three genes exhibited lower expression levels in the incompatible and compatible interactions. These results further confirmed that defence-related genes might be involved in the defence response of pepper to P. capsici attack.
    European Journal of Plant Pathology 07/2013; 136(3). DOI:10.1007/s10658-013-0193-8 · 1.71 Impact Factor