ABSTRACT
The NPRI (nonexpressor of pathogenesis-related genes (1) gene, firstly cloned in Arabidopsis thaliana, is a key gene involved in regulation of plant disease resistance. It plays a pivotal role not only in systemic acquired resistance (SAR) and induced systemic resistance (ISR), but also in basic resistance and resistance (R) gene-dependent resistance. NPR1 monomerization induced by enhanced reducing condition after oxidative burst, and the accumulation of NPR1 monomers in the nuclei, are required and enough for expression of PR (pathogenesis-related) genes and SAR. NPR1 regulates PR gene expression through interaction with TGA transcription factors (TF). As a cross-talk point of a variety of defense signaling pathways, probably through direct or indirect interacting with some WRKY TFs and a NPR1-like protein NPR4, NPR1 is essential in balancing salicylic acid- and jasmonic acid- dependent signal transduction pathways, which is achieved through an unknown mechanism in the cytosol. The possible application of NPR1 in plant protection is also discussed in this review.
Subject(s)
Arabidopsis Proteins , Genetics , Cyclopentanes , Metabolism , Pharmacology , Gene Expression Regulation, Plant , Genetics , Oxylipins , Metabolism , Pharmacology , Plant Diseases , Genetics , Plants, Genetically Modified , Salicylic Acid , Metabolism , Pharmacology , Signal TransductionABSTRACT
One type of important plant disease resistance, gene-for-gene resistance, is resulted from the interactions between products of the pathogen avirulence (Avr) genes and their matching plant resistance (R) genes. Avr genes have been cloned from a variety of pathogens including fungi, bacteria, viruses and oomycetes. No significant homology is found between sequences of the most cloned Avr genes and those of known proteins or between those of themselves. However, significant homology has been found between sequences of the cloned R genes and those of known proteins or between those of themselves. R proteins consist of similar domains. It has been reported that hypersensitive cell death and resistance, which are induced by interactions between products of different Avr/R gene pairs consisting of similar R genes but different Avr genes, are distinct in development speed, strength, and organ and tissue specificity. Avr genes have dual functions: Pathogens containing Avr genes are avirulent to plants carrying the matching R genes, while they are virulent in race, strain, pathovar or species-specific way to plants without carrying the matching R genes.