Putting Plant Disease Resistance Genes to Work

Abstract

Semi-dominant plant disease resistance (R) genes confer recognition of and response to specific races of pathogen that carry a corresponding Avirulence (Avr) gene. R proteins are presumed to recognise pathogen Avr gene-encoded products, or compatibility factors, that are likely to be involved in pathogenicity on the host. R genes against various important diseases have been used by plant breeders, but when deployed in monocultures, resistance frequently breaks down as races of the pathogen emerge that can overcome the R gene through recessive mutations in the corresponding Avr gene. Nevertheless, in nature, R genes have been maintained. In Arabidopsis, {\textasciitilde}164 homologs of the largest class of R genes exist. These R genes encode proteins of the nucleotide binding-leucine rich repeat (NB-LRR) class (Dangl and Jones, 2001).