Project description:Plant Elicitor Peptides (Peps) are conserved regulators of defense responses across diverse plant species and are multigene families in most species. However, the functional relevance of Peps as multigene families remains largely undefined. While Arabidopsis Peps appear largely redundant in function, previous work examining Pep-induced responses in maize implied specificity of function. To better define function of individual ZmPeps, activities of each peptide were examined by assessing changes in defense-associated phytohormones, specialized metabolites and global gene expression patterns. In addition to delineating individual ZmPep and ZmPEPR activities, these experiments led to a number of new insights into Pep signaling. ZmPROPEP precursors were found to harbor multiple ZmPeps, a phenomenon not previously observed. In all, seven new ZmPeps were identified and together the family members were found to have specific activities defined by relative magnitude of response output rather than uniqueness. A striking correlation between ZmPep-elicited changes in levels of jasmonic acid and ethylene and the magnitude of induced defense responses was observed, indicating that ZmPeps regulate immune output through rheostat-like regulation of phytohormone levels. Peptide structure-function studies and ligand-receptor modeling revealed structural features critical to ZmPep signaling function. Structural analysis also led to identification of ZmPep5a as a potential antagonist peptide able to competitively inhibit activity of other ZmPeps, a regulatory mechanism not previously observed for this family. Using heterologous expression assays, endogenous gene expression patterns and analysis of CRISPR/Cas9 generated knockout plants, ZmPEPR1 was found to be the dominant receptor regulating ZmPep-mediated anti-herbivore defenses in planta.
Project description:Rice is a staple food crop worldwide, and its production is severely threatened by phloem-feeding insect herbivores, particularly the brown planthopper (BPH, Nilaparvata lugens), and destructive pathogens. Despite the identification of many BPH resistance genes, the molecular basis of rice resistance to BPH remains largely unclear. Here, we report that the plant elicitor peptide (Pep) signalling confers rice resistance to BPH. Both rice PEP RECEPTORs (PEPRs) and PRECURSORs of PEP (PROPEPs), particularly OsPROPEP3, were transcriptionally induced in leaf sheaths upon BPH infestation. Knockout of OsPEPRs impaired rice resistance to BPH, whereas exogenous application of OsPep3 improved the resistance. Hormone measurement and co-profiling of transcriptomics and metabolomics in OsPep3-treated rice leaf sheaths suggested potential contributions of jasmonic acid biosynthesis, lipid metabolism and phenylpropanoid metabolism to OsPep3-induced rice immunity. Moreover, OsPep3 elicitation also strengthened rice resistance to the fungal pathogen Magnaporthe oryzae and bacterial pathogen Xanthamonas oryzae pv. oryzae and provoked immune responses in wheat. Collectively, this work demonstrates a previously unappreciated importance of the Pep signalling in plants for combating piercing-sucking insect herbivores and promises exogenous application of OsPep3 as an eco-friendly immune stimulator in agriculture for crop protection against a broad spectrum of insect pests and pathogens.
Project description:To see the function of OsCERK1 receptor-like kinase in the chitin elicitor signaling in Rice, we compared the gene expression profiles in the chitin oligosaccharide treated cultured rice cells of vector control and OsCERK1 knock-down mutant (RNAi). Keywords: Defense response
Project description:We identified a leucine-rich repeat receptor kinase (IbLRR-RK1) that is induced upon wounding and herbivory, and related to peptide-elicitor receptors (PEPRs) from tomato and Arabidopsis. We also identified a gene encoding a precursor protein comprising a peptide ligand (IbPep1) for IbLRR-RK1. RNAseq of I. batatas reveals differentially expressed genes (DEGs) upon IbPep1 and IbHypSysIV treatment
Project description:To characterize the differentially expressed genes between adding fungal elicitor and without fungal elicitor on Streptomyces natalensis HW-2
Project description:Recognizing pathogen-associated molecular patterns on the cell surface is crucial for plant immunity. The proteinaceous nature of many of these patterns suggests that secreted proteases play important roles in their formation and stability. Here we demonstrate that the apoplastic subtilase SBT5.2a inactivates the immunogenicity of cold-shock proteins (CSPs) of the bacterial plant pathogen Pseudomonas syringae by cleaving within the immunogenic csp22 epitope. Consequently, mutant plants lacking SBT5.2a activity retain higher levels of csp22, leading to enhanced immune responses and reduced pathogen growth. SBT5.2 sensitivity is influenced by sequence variation surrounding the cleavage site and probably extends to CSPs from other bacterial species. These findings suggest that variations in csp22 stability among bacterial pathogens are a crucial factor in plant-bacteria interactions and that pathogens exploit plant proteases to avoid pattern recognition.
Project description:To see the function of CERK1 receptor-like kinase in the chitin elicitor signaling in Arabidopsis, we compared the gene expression profiles in the chitin oligosaccharide treated seedlings of wild type A. thaliana and CERK1 knock-out mutant. Keywords: Defense response
Project description:To see the function of OsCERK1 receptor-like kinase in the chitin elicitor signaling in Rice, we compared the gene expression profiles in the chitin oligosaccharide treated cultured rice cells of vector control and OsCERK1 knock-down mutant (RNAi). Keywords: Defense response 1,Chitin oligosaccharide treatment (vector control), 2,Chitin oligosaccharide treatment (vector control) color swap, 3,Chitin oligosaccharide treatment (OsCERK1 RNAi), 4,Chitin oligosaccharide treatment (OsCERK1 RNAi) color swap
Project description:Xylella fastidiosa is a plant pathogenic bacterium that has been introduced in the European Union (EU), threatening the agricultural economy of relevant Mediterranean crops such as almond (Prunus dulcis). Plant defense elicitor peptides would be promising to manage diseases such as almond leaf scorch but their effect on the host has not been fully studied. In this work, the response of almond plants to the defense elicitor peptide flg22-NH2 was studied in-depth using RNA-seq, confirming the activation of the salicylic acid and abscisic acid pathways. Marker genes related to the response triggered by flg22-NH2 were used to study the effect of the application strategy of the peptide on almond plants and to depict its time course. The application of flg22-NH2 by endotherapy triggered the highest number of upregulated genes, especially at 6 hours after the treatment. A library of peptides that include BP100-flg15, HpaG23, FV7, RIJK2, PIP-1, Pep13, BP16-Pep13, flg15-BP100 and BP16 triggered a stronger defense response in almond plants than flg22-NH2. The best candidate, FV7, when applied by endotherapy on almond plants inoculated with X. fastidiosa, significantly reduced levels of the pathogen and decreased disease symptoms. Therefore, these novel plant defense elicitors are suitable candidates to manage diseases caused by X. fastidiosa, in particular almond leaf scorch.
Project description:Papain-like cysteine proteases (PLCPs) play important roles in plant defense mechanisms. Previous work identified a set of five apoplastic PLCPs (CP1A, CP1B, CP2, XCP2 and CatB) which are crucial for the orchestration of SA-dependent defense signaling and vice versa in maize (Zea mays). One central question from these findings is which mechanism is triggered by apoplastic PLCPs to induce SA-dependent defenses. By a mass spectrometry approach we discovered a novel peptide (Zip1 = Zea mays immune signaling peptide) to be enriched in apoplastic fluid upon SA treatment. Zip1 induces PR-gene expression when applied to naїve maize leaves. Moreover, it activates apoplastic PLCPs similar as SA does, suggesting Zip1 to play an important role in SA-mediated defense signaling. In vitro studies using recombinant protein showed that CP1A and CP2, but not XCP2 and CatB, release Zip1 from its pro-peptide (PROZIP1) in vitro. Strikingly, metabolite analysis showed direct induction of SA de novo synthesis by Zip1 in maize leaves. In line with this, RNA sequencing revealed that Zip1-mediated changes in maize gene expression largely resemble SA-induced responses. Consequently, Zip1 increases maize susceptibility to the necrotrophic fungal pathogen Botrytis cinerea. In summary, this study identifies the PLCP-released peptide signal Zip1, which triggers SA signaling in maize.