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Plant Immunity (plant + immunity)

Distribution by Scientific Domains
Life Sciences100%

Selected Abstracts

Epigenetic control of plant immunity

MOLECULAR PLANT PATHOLOGY, Issue 4 2010
MARĶA E. ALVAREZ
SUMMARY In eukaryotic genomes, gene expression and DNA recombination are affected by structural chromatin traits. Chromatin structure is shaped by the activity of enzymes that either introduce covalent modifications in DNA and histone proteins or use energy from ATP to disrupt histone,DNA interactions. The genomic ,marks' that are generated by covalent modifications of histones and DNA, or by the deposition of histone variants, are susceptible to being altered in response to stress. Recent evidence has suggested that proteins generating these epigenetic marks play crucial roles in the defence against pathogens. Histone deacetylases are involved in the activation of jasmonic acid- and ethylene-sensitive defence mechanisms. ATP-dependent chromatin remodellers mediate the constitutive repression of the salicylic acid-dependent pathway, whereas histone methylation at the WRKY70 gene promoter affects the activation of this pathway. Interestingly, bacterial-infected tissues show a net reduction in DNA methylation, which may affect the disease resistance genes responsible for the surveillance against pathogens. As some epigenetic marks can be erased or maintained and transmitted to offspring, epigenetic mechanisms may provide plasticity for the dynamic control of emerging pathogens without the generation of genomic lesions. [source]

Post-translational modification of host proteins in pathogen-triggered defence signalling in plants

MOLECULAR PLANT PATHOLOGY, Issue 4 2008
IRIS J. E. STULEMEIJER
SUMMARY Microbial plant pathogens impose a continuous threat to global food production. Similar to animals, an innate immune system allows plants to recognize pathogens and swiftly activate defence. To activate a rapid response, receptor-mediated pathogen perception and subsequent downstream signalling depends on post-translational modification (PTM) of components essential for defence signalling. We discuss different types of PTMs that play a role in mounting plant immunity, which include phosphorylation, glycosylation, ubiquitination, sumoylation, nitrosylation, myristoylation, palmitoylation and glycosylphosphatidylinositol (GPI)-anchoring. PTMs are rapid, reversible, controlled and highly specific, and provide a tool to regulate protein stability, activity and localization. Here, we give an overview of PTMs that modify components essential for defence signalling at the site of signal perception, during secondary messenger production and during signalling in the cytoplasm. In addition, we discuss effectors from pathogens that suppress plant defence responses by interfering with host PTMs. [source]

ER quality control of immune receptors and regulators in plants

CELLULAR MICROBIOLOGY, Issue 6 2010
Yusuke Saijo
Summary Like in animals, cell surface and intracellular receptors mediate immune recognition of potential microbial intruders in plants. Membrane-localized pattern recognition receptors (PRRs) initiate immune responses upon perception of cognate microbe-associated molecular patterns (MAMPs). MAMP-triggered immunity provides a first line of defence that restricts the invasion and propagation of both adapted and non-adapted pathogens. The Leu-rich repeat (LRR) receptor protein kinases (RKs) define a major class of trans-membrane receptors in plants, of which some members are engaged in MAMP recognition and/or defence signalling. The endoplasmic reticulum (ER) quality control (QC) systems monitor N-glycosylation and folding states of the extracellular, ligand-binding LRR domains of LRR-RKs. Recent progress reveals a critical role of evolutionarily conserved ERQC components for different layers of plant immunity. N-glycosylation appears to play a role in ERQC fidelity rather than in ligand binding of LRR-RKs. Moreover, even closely related PRRs show receptor-specific requirements for N-glycosylation. These findings are reminiscent of the earlier defined function of the cytosolic chaperon complex for LRR domain-containing intracellular immune receptors. QC of the LRR domains might provide a basis not only for the maintenance but also for diversification of recognition specificities for immune receptors in plants. [source]

Mutualism versus pathogenesis: the give-and-take in plant,bacteria interactions

CELLULAR MICROBIOLOGY, Issue 3 2009
Marķa J. Soto
Summary Pathogenic bacteria and mutualistic rhizobia are able to invade and establish chronic infections within their host plants. The success of these plant,bacteria interactions requires evasion of the plant innate immunity by either avoiding recognition or by suppressing host defences. The primary plant innate immunity is triggered upon recognition of common microbe-associated molecular patterns. Different studies reveal striking similarities between the molecular bases underlying the perception of rhizobial nodulation factors and microbe-associated molecular patterns from plant pathogens. However, in contrast to general elicitors, nodulation factors can control plant defences when recognized by their cognate legumes. Nevertheless, in response to rhizobial infection, legumes show transient or local defence-like responses suggesting that Rhizobium is perceived as an intruder although the plant immunity is controlled. Whether these responses are involved in limiting the number of infections or whether they are required for the progression of the interaction is not yet clear. Further similarities in both plant,pathogen and Rhizobium,legume associations are factors such as surface polysaccharides, quorum sensing signals and secreted proteins, which play important roles in modulating plant defence responses and determining the outcome of the interactions. [source]

Biological systems of the host cell involved in Agrobacterium infection

CELLULAR MICROBIOLOGY, Issue 1 2007
Vitaly Citovsky
Summary Genetic transformation of plants by Agrobacterium, which in nature causes neoplastic growths, represents the only known case of trans -kingdom DNA transfer. Furthermore, under laboratory conditions, Agrobacterium can also transform a wide range of other eukaryotic species, from fungi to sea urchins to human cells. How can the Agrobacterium virulence machinery function in such a variety of evolutionarily distant and diverse species? The answer to this question lies in the ability of Agrobacterium to hijack fundamental cellular processes which are shared by most eukaryotic organisms. Our knowledge of these host cellular functions is critical for understanding the molecular mechanisms that underlie genetic transformation of eukaryotic cells. This review outlines the bacterial virulence machinery and provides a detailed discussion of seven major biological systems of the host cell,cell surface receptor arrays, cellular motors, nuclear import, chromatin targeting, targeted proteolysis, DNA repair, and plant immunity , thought to participate in the Agrobacterium -mediated genetic transformation. [source]