Resistance genes (R-Genes) are genes in plant genomes that convey plant disease resistance against pathogens by producing R proteins. The main class of R-genes consist of a nucleotide binding domain (NB) and a leucine rich repeat (LRR) domain(s) and are often referred to as (NB-LRR) R-genes. Generally, the NB domain binds either ATP/ADP or GTP/GDP. The LRR domain is often involved in protein-protein interactions as well as ligand binding. NB-LRR R-genes can be further subdivided into toll interleukin 1 receptor (TIR-NB-LRR) and coiled-coil (CC-NB-LRR).
Resistance can be conveyed through a number of mechanisms including:
- The R protein interacts directly with an Avr gene (Avirulence gene) product of a pathogen (see Gene-for-Gene relationship).
- The R protein guards another protein that detects degradation by an Avr gene (see Guard Hypothesis).
- The R protein may detect a Pathogen-Associated Molecular Pattern or PAMP (alternatively called MAMP for microbe-associated molecular pattern).
- The R protein encodes enzyme that degrades a toxin produced by a pathogen.
Once the R protein has detected the presence of a pathogen, the plant can mount a defence against the pathogen. Because R genes confer resistance against specific pathogens, it is possible to transfer an R gene from one plant to another and make a plant resistant to a particular pathogen.
- Knepper, Caleb; Day, Brad (March 2010). "From Perception to Activation: The Molecular-Genetic and Biochemical Landscape of Disease Resistance Signaling in Plants". The Arabidopsis Book: 1–17. doi:10.1199/tab.0124.
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