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1.
Transcriptional Factors Regulate Plant Stress Responses through Mediating Secondary Metabolism.
Meraj, TA, Fu, J, Raza, MA, Zhu, C, Shen, Q, Xu, D, Wang, Q
Genes. 2020;(4)
Abstract
Plants are adapted to sense numerous stress stimuli and mount efficient defense responses by directing intricate signaling pathways. They respond to undesirable circumstances to produce stress-inducible phytochemicals that play indispensable roles in plant immunity. Extensive studies have been made to elucidate the underpinnings of defensive molecular mechanisms in various plant species. Transcriptional factors (TFs) are involved in plant defense regulations through acting as mediators by perceiving stress signals and directing downstream defense gene expression. The cross interactions of TFs and stress signaling crosstalk are decisive in determining accumulation of defense metabolites. Here, we collected the major TFs that are efficient in stress responses through regulating secondary metabolism for the direct cessation of stress factors. We focused on six major TF families including AP2/ERF, WRKY, bHLH, bZIP, MYB, and NAC. This review is the compilation of studies where researches were conducted to explore the roles of TFs in stress responses and the contribution of secondary metabolites in combating stress influences. Modulation of these TFs at transcriptional and post-transcriptional levels can facilitate molecular breeding and genetic improvement of crop plants regarding stress sensitivity and response through production of defensive compounds.
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2.
PRRs and NB-LRRs: From Signal Perception to Activation of Plant Innate Immunity.
Noman, A, Aqeel, M, Lou, Y
International journal of molecular sciences. 2019;(8)
Abstract
To ward off pathogens and pests, plants use a sophisticated immune system. They use pattern-recognition receptors (PRRs), as well as nucleotide-binding and leucine-rich repeat (NB-LRR) domains, for detecting nonindigenous molecular signatures from pathogens. Plant PRRs induce local and systemic immunity. Plasma-membrane-localized PRRs are the main components of multiprotein complexes having additional transmembrane and cytosolic kinases. Topical research involving proteins and their interactive partners, along with transcriptional and posttranscriptional regulation, has extended our understanding of R-gene-mediated plant immunity. The unique LRR domain conformation helps in the best utilization of a surface area and essentially mediates protein-protein interactions. Genome-wide analyses of inter- and intraspecies PRRs and NB-LRRs offer innovative information about their working and evolution. We reviewed plant immune responses with relevance to PRRs and NB-LRRs. This article focuses on the significant functional diversity, pathogen-recognition mechanisms, and subcellular compartmentalization of plant PRRs and NB-LRRs. We highlight the potential biotechnological application of PRRs and NB-LRRs to enhance broad-spectrum disease resistance in crops.
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3.
The Role of Proteases in the Virulence of Plant Pathogenic Bacteria.
Figaj, D, Ambroziak, P, Przepiora, T, Skorko-Glonek, J
International journal of molecular sciences. 2019;(3)
Abstract
A pathogenic lifestyle is inextricably linked with the constant necessity of facing various challenges exerted by the external environment (both within and outside the host). To successfully colonize the host and establish infection, pathogens have evolved sophisticated systems to combat the host defense mechanisms and also to be able to withstand adverse environmental conditions. Proteases, as crucial components of these systems, are involved in a variety of processes associated with infection. In phytopathogenic bacteria, they play important regulatory roles and modulate the expression and functioning of various virulence factors. Secretory proteases directly help avoid recognition by the plant immune systems, and contribute to the deactivation of the defense response pathways. Finally, proteases are important components of protein quality control systems, and thus enable maintaining homeostasis in stressed bacterial cells. In this review, we discuss the known protease functions and protease-regulated signaling processes associated with virulence of plant pathogenic bacteria.
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4.
Review: Potential biotechnological assets related to plant immunity modulation applicable in engineering disease-resistant crops.
Silva, MS, Arraes, FBM, Campos, MA, Grossi-de-Sa, M, Fernandez, D, Cândido, ES, Cardoso, MH, Franco, OL, Grossi-de-Sa, MF
Plant science : an international journal of experimental plant biology. 2018;:72-84
Abstract
This review emphasizes the biotechnological potential of molecules implicated in the different layers of plant immunity, including, pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI), effector-triggered susceptibility (ETS), and effector-triggered immunity (ETI) that can be applied in the development of disease-resistant genetically modified (GM) plants. These biomolecules are produced by pathogens (viruses, bacteria, fungi, oomycetes) or plants during their mutual interactions. Biomolecules involved in the first layers of plant immunity, PTI and ETS, include inhibitors of pathogen cell-wall-degrading enzymes (CWDEs), plant pattern recognition receptors (PRRs) and susceptibility (S) proteins, while the ETI-related biomolecules include plant resistance (R) proteins. The biomolecules involved in plant defense PTI/ETI responses described herein also include antimicrobial peptides (AMPs), pathogenesis-related (PR) proteins and ribosome-inhibiting proteins (RIPs), as well as enzymes involved in plant defensive secondary metabolite biosynthesis (phytoanticipins and phytoalexins). Moreover, the regulation of immunity by RNA interference (RNAi) in GM disease-resistant plants is also considered. Therefore, the present review does not cover all the classes of biomolecules involved in plant innate immunity that may be applied in the development of disease-resistant GM crops but instead highlights the most common strategies in the literature, as well as their advantages and disadvantages.
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5.
Molecular networks in plant-pathogen holobiont.
Nobori, T, Mine, A, Tsuda, K
FEBS letters. 2018;(12):1937-1953
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Abstract
Plant immune receptors enable detection of a multitude of microbes including pathogens. The recognition of microbes activates various plant signaling pathways, such as those mediated by phytohormones. Over the course of coevolution with microbes, plants have expanded their repertoire of immune receptors and signaling components, resulting in highly interconnected plant immune networks. These immune networks enable plants to appropriately respond to different types of microbes and to coordinate immune responses with developmental programs and environmental stress responses. However, the interconnectivity in plant immune networks is exploited by microbial pathogens to promote pathogen fitness in plants. Analogous to plant immune networks, virulence-related pathways in bacterial pathogens are also interconnected. Accumulating evidence implies that some plant-derived compounds target bacterial virulence networks. Thus, the plant immune and bacterial virulence networks intimately interact with each other. Here, we highlight recent insights into the structures of the plant immune and bacterial virulence networks and the interactions between them. We propose that small molecules derived from plants and/or bacterial pathogens connect the two molecular networks, forming supernetworks in the plant-bacterial pathogen holobiont.
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L-type lectin receptor kinases: New forces in plant immunity.
Wang, Y, Bouwmeester, K
PLoS pathogens. 2017;(8):e1006433
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7.
[Immunostimulatory properties of mistletoe extracts and their application in oncology].
Wrotek, S, Skawiński, R, Kozak, W
Postepy higieny i medycyny doswiadczalnej (Online). 2014;:1216-24
Abstract
For a long time cancer immunotherapy was overshadowed by chemotherapy and radiotherapy. Recently, "Science", one of the world's top scientific journals, named the stimulation of the body's own immune system to fight cancer cells as the "breakthrough of the year". In Germany, Switzerland and Austria, extracts derived from mistletoe (Viscum album L.) such as Iscador, Abnobaviscum, Helixor, Iscar, Iscucin and Isorel have been used in oncology for many years. These extracts have immunomodulating and immunostimulating properties, as demonstrated by experimental studies as well as in clinical trials. The aim of our paper is to present immunological disorders associated with cancer, which can be counteracted by treatment with extracts derived from mistletoe. Although these drugs cannot replace conventional cancer treatment, they may improve the patient's quality and length of life.
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Effector-triggered defence against apoplastic fungal pathogens.
Stotz, HU, Mitrousia, GK, de Wit, PJ, Fitt, BD
Trends in plant science. 2014;(8):491-500
Abstract
R gene-mediated host resistance against apoplastic fungal pathogens is not adequately explained by the terms pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) or effector-triggered immunity (ETI). Therefore, it is proposed that this type of resistance is termed 'effector-triggered defence' (ETD). Unlike PTI and ETI, ETD is mediated by R genes encoding cell surface-localised receptor-like proteins (RLPs) that engage the receptor-like kinase SOBIR1. In contrast to this extracellular recognition, ETI is initiated by intracellular detection of pathogen effectors. ETI is usually associated with fast, hypersensitive host cell death, whereas ETD often triggers host cell death only after an elapsed period of endophytic pathogen growth. In this opinion, we focus on ETD responses against foliar fungal pathogens of crops.
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Analysis of the effects of polymorphism on pollen profilin structural functionality and the generation of conformational, T- and B-cell epitopes.
Jimenez-Lopez, JC, Rodríguez-García, MI, Alché, JD
PloS one. 2013;(10):e76066
Abstract
An extensive polymorphism analysis of pollen profilin, a fundamental regulator of the actin cytoskeleton dynamics, has been performed with a major focus in 3D-folding maintenance, changes in the 2-D structural elements, surface residues involved in ligands-profilin interactions and functionality, and the generation of conformational and lineal B- and T-cell epitopes variability. Our results revealed that while the general fold is conserved among profilins, substantial structural differences were found, particularly affecting the special distribution and length of different 2-D structural elements (i.e. cysteine residues), characteristic loops and coils, and numerous micro-heterogeneities present in fundamental residues directly involved in the interacting motifs, and to some extension these residues nearby to the ligand-interacting areas. Differential changes as result of polymorphism might contribute to generate functional variability among the plethora of profilin isoforms present in the olive pollen from different genetic background (olive cultivars), and between plant species, since biochemical interacting properties and binding affinities to natural ligands may be affected, particularly the interactions with different actin isoforms and phosphoinositides lipids species. Furthermore, conspicuous variability in lineal and conformational epitopes was found between profilins belonging to the same olive cultivar, and among different cultivars as direct implication of sequences polymorphism. The variability of the residues taking part of IgE-binding epitopes might be the final responsible of the differences in cross-reactivity among olive pollen cultivars, among pollen and plant-derived food allergens, as well as between distantly related pollen species, leading to a variable range of allergy reactions among atopic patients. Identification and analysis of commonly shared and specific epitopes in profilin isoforms is essential to gain knowledge about the interacting surface of these epitopes, and for a better understanding of immune responses, helping design and development of rational and effective immunotherapy strategies for the treatment of allergy diseases.
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10.
Allergenic lipid transfer proteins from plant-derived foods do not immunologically and clinically behave homogeneously: the kiwifruit LTP as a model.
Bernardi, ML, Giangrieco, I, Camardella, L, Ferrara, R, Palazzo, P, Panico, MR, Crescenzo, R, Carratore, V, Zennaro, D, Liso, M, et al
PloS one. 2011;(11):e27856
Abstract
BACKGROUND Food allergy is increasingly common worldwide. Tools for allergy diagnosis measuring IgE improved much since allergenic molecules and microarrays started to be used. IgE response toward allergens belonging to the same group of molecules has not been comprehensively explored using such approach yet. OBJECTIVE Using the model of lipid transfer proteins (LTPs) from plants as allergens, including two new structures, we sought to define how heterogeneous is the behavior of homologous proteins. METHODS Two new allergenic LTPs, Act d 10 and Act c 10, have been identified in green (Actinidia deliciosa) and gold (Actinidia chinensis) kiwifruit (KF), respectively, using clinically characterized allergic patients, and their biochemical features comparatively evaluated by means of amino acid sequence alignments. Along with other five LTPs from peach, mulberry, hazelnut, peanut, mugwort, KF LTPs, preliminary tested positive for IgE, have been immobilized on a microarray, used for IgE testing 1,003 allergic subjects. Comparative analysis has been carried out. RESULTS Alignment of Act d 10 primary structure with the other allergenic LTPs shows amino acid identities to be in a narrow range between 40 and 55%, with a number of substitutions making the sequences quite different from each other. Although peach LTP dominates the IgE immune response in terms of prevalence, epitope recognition driven by sequence heterogeneity has been recorded to be distributed in a wide range of behaviors. KF LTPs IgE positive results were obtained in a patient subset IgE positive for the peach LTP. Anyhow, the negative results on homologous molecules allowed us to reintroduce KF in patients' diet. CONCLUSION The biochemical nature of allergenic molecule belonging to a group of homologous ones should not be taken as proof of immunological recognition as well. The availability of panels of homologous molecules to be tested using microarrays is valuable to address the therapeutic intervention.