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: 3.94). 06/2011; 24(6):671-84. DOI: 10.1094/MPMI-08-10-0183
Source: PubMed


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.

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Available from: Seon-In Yeom, Mar 11, 2014
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    • "Further studies will be required to understand how CaXEGIP1 and hemicellulose xyloglucan regulate pepper defense and/or cell death during the pathogen infection. Recently, Yeom et al. (2011) screened pepper Secretome (CaS) genes encoding defenserelated extracellular proteins using yeast-based signalsequence trap screening. From this screening, 101 unique pepper genes were identified and VIGS of several CaS genes compromised non-host pathogen Pst-induced HR cell death in pepper. "
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    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.
    Full-text · Article · Sep 2014 · Planta
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    • "Death areas that developed on the infiltrated leaf surface were monitored 6, 12, 24 and 48 h after treatment with elicitors. Cell death was also checked using an electrolyte leakage method, adapted from the method of Yeom et al. (2011). Leaves were infiltrated with elicitors under the leaf surface, and leaf discs (1 cm in diameter) were collected from the leaf 3, 6 and 12 h after treatment. "
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    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.
    Full-text · Article · Jan 2014 · Journal of General Plant Pathology
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    • "Plants were grown in a growth chamber at 25 ○ C under 16 and 8 h of light and dark, respectively. At the six-leaf stage, pepper plants were inoculated with P. capsici (Yeom et al., 2011). P. capsici-infected plants were collected from the experimental field of Northwest A&F University (Yangling, P.R. China). "
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    ABSTRACT: Based on culture isolation and morphological observation blight-infected pepper plants in Shaanxi Province, China, we identified the pathogen causing pepper phytophthora blight as Phytophthora capsici. Varieties that differed in resistance (CM334, PBC602, and B27) were inoculated with this pathogen. The root activity of resistant CM334 variety was the highest while that of susceptible B27 variety was the lowest. Also, significant differences in the activity of POD, PAL, and β-1,3-glucanase were found; there was a positive correlation between disease resistance and activity of these three enzymes. We inhibited mycelial growth and sporangia formation of P. capsici using crude β-1,3-glucanase and PAL enzymes isolated from the resistant variety CM334 after it had been inoculated with P. capsici. These two enzymes had a synergistic effect on inhibition of P. capsici mycelial growth and sporangia formation. Expression of the defensive genes CaPO1, CaBGLU, CaBPR1, and CaRGA in the three varieties was higher in the leaves than in the roots. All three genes were upregulated in infected leaves and roots of the pepper plants, always expressing at higher levels in the resistant cultivar than in the susceptible cultivar, suggesting that the differences in resistance among the pepper genotypes involve differences in the timing and magnitude of the defense response.
    Full-text · Article · Sep 2013 · Genetics and molecular research: GMR
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