Pi5 and Pii Paired NLRs Are Functionally Exchangeable and Confer Similar Disease Resistance Specificity.

Effector-triggered immunity (ETI) is an effective layer of plant defense initiated upon recognition of avirulence (Avr) effectors from pathogens by cognate plant disease resistance (R) proteins. In rice, a large number of genes have been characterized from various cultivars and have greatly contributed to breeding programs to improve resistance against the rice blast pathogen . The extreme diversity of gene repertoires is thought to be a result of co-evolutionary history between rice and its pathogens including . Here we show that is an allele of Pi5 by DNA sequence characterization and complementation analysis. and cDNAs were cloned by reverse transcription polymerase chain reaction from the -carrying cultivar Fujisaka5 . The complementation test in susceptible rice cultivar Dongjin demonstrated that the rice blast resistance mediated by Pii , similar to , requires the presence of two nucleotide-binding leucine-rich repeat genes, and . Consistent with our hypothesis that and are functionally indistinguishable, the replacement of by and by , respectively, does not change the level of disease resistance to M. oryzae carrying AVR-Pii. Surprisingly, Exo70F3, required for -mediated resistance, is dispensable for -mediated resistance. Based on our results, despite similarities observed between Pi5 and Pii, we hypothesize that Pi5 and Pii pairs require partially distinct mechanisms to function.