Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 1, 2006
Publication Date: January 10, 2007
Citation: Jia, Y. 2007. Plants and pathogens engage in trench warfare-knowledge learned from natural variation of rice blast resistance gene Pi-ta. Plant and Animal Genome Conference Proceedings. Technical Abstract: It takes no time for a disease to find a way around the plant’s defense when a resistant plant is grown. This never-ending battle between plants and pathogens is similar to an arms race with each side developing its best weapon. To gain a better understanding of the co-evolutionary dynamic of plant-pathogen interaction, we have been investigating the natural variation of a resistance gene Pi-ta in rice that detects the pathogen Magnaporthe grisea’s avirulence gene AVR-Pita when an active defense response is triggered. Pi-ta is similar to the major class of NBS-LRR type resistance genes, and its resistance specificity resides in an amino acid residue at position 918. When this amino acid residue is alanine, Pi-ta confers resistance to M. grisea races containing AVR-Pita whereas when alanine is substituted by serine, due to a single nucleotide alteration, Pi-ta loses its resistance specificity. Moreover, most of the Pi-ta allele differences in rice accessions and its wild relatives were found in a non-coding intron region that does not affect functionality of the resistance gene product. In contrast, AVR-Pita is known to be highly variable in promoting disease. Thus, we suggest that the Pi-ta and AVR-Pita interaction follows a trench warfare model where resistant and susceptible plants are maintained by being selected for or against at different times during natural pathogen epidemics.