R proteins as fundamentals of plant innate immunity

Abstract

Abstract:Plants are attacked by a wide spectrum of pathogens, being the targets of viruses, bacteria, fungi, protozoa, nematodes and insects. Over the course of their evolution, plants have developed numerous defense mechanisms including the chemical and physical barriers that are constitutive elements of plant cell responses locally and/or systemically. However, the modern approach in plant sciences focuses on the evolution and role of plant protein receptors corresponding to specific pathogen effectors. The recognition of an invader's molecules could be in most cases a prerequisite sine qua non for plant survival. Although the predicted three-dimensional structure of plant resistance proteins (R) is based on research on their animal homologs, advanced technologies in molecular biology and bioinformatics tools enable the investigation or prediction of interaction mechanisms for specific receptors with pathogen effectors. Most of the identified R proteins belong to the NBS-LRR family. The presence of other domains (including the TIR domain) apart from NBS and LRR is fundamental for the classification of R proteins into subclasses. Recently discovered additional domains (e.g. WRKY) of R proteins allowed the examination of their localization in plant cells and the role they play in signal transduction during the plant resistance response to biotic stress factors. This review focuses on the current state of knowledge about the NBS-LRR family of plant R proteins: their structure, function and evolution, and the role they play in plant innate immunity.

Stars and Symbiosis: MicroRNA- and MicroRNA*-Mediated Transcript Cleavage Involved in Arbuscular Mycorrhizal Symbiosis

“…Our study indicates that four primarily moderately conserved miRNAs, namely miR1510a*, miR1507, miR2678 (Szittya et al, 2008;Lelandais-Brière et al, 2009), and miR5213, regulate disease resistance genes. Plants have evolved a general defense response to biotic interactions involving toll and interleukin-1 receptor (TIR)/nucleotide-binding site-Leu-rich repeat disease resistance genes and PR proteins (Jones and Dangl, 2006;Głowacki et al, 2011). Although basal defense mechanisms, which include the accumulation of phenolic compounds and PR proteins, are activated upon the interaction with AM fungi (Campos-Soriano et al, 2010;Abdel-Fattah et al, 2011), we observed that mRNA levels of many of the miRNA-targeted disease resistance genes are decreased in mycorrhizal roots.…”

Response to biotic and oxidative stress in Arabidopsis thaliana: Analysis of variably phosphorylated proteins

“…Pathogens must circumvent or suppress this first-line surveillance mechanism in order to develop disease. On the other hand, some plant varieties also express a mechanism known as gene-for-gene resistance [4], which relies on the recognition of specific avirulence gene products from the pathogen by complementary R receptors. This recognition elicits a set of biochemical reactions, including generation of H 2 O 2 and reactive oxygen species (ROS), lipid peroxidation, ion fluxes, protein phosphorylation and phytoalexin synthesis, which are generally referred to as the Hypersensitive Response (HR) [5].…”

A strategy for building an amplified transcriptional switch to detect bacterial contamination of plants

“…In the preliminary transient transformation experiments in plant protoplasts, the fire fly luciferase reporter was used. For a different application, luciferase reporter can be substituted by the flg22 elicitor itself (Gómez-Gómez and Boller 2000; Zipfel and Felix 2005), or alternatively, by the resistance R protein genes known to induce the hypersensitive result which may lead to apoptosis (Glowacki et al 2010). Similar Gal4DBD-VP16-based transcriptional feedback loops were previously built by others for the expression of luciferase reporter in plants (Schwechheimer et al 2000), the amplification of cytotoxic diphtheria toxin A gene in mammalian cell lines (Imhof et al 2000), or in monitoring translation of the second coding region (feedback effector) within a dicistronic mRNA (Zhou et al 2005).…”