Vo KTX, Lee SK, Halane MK, Song MY, Hoang TV, Kim CY, Park SY, Jeon J, Kim ST, Sohn KH, Jeon JS.

Mol Cells. 2019 Sep 30;42(9):637-645. doi: 10.14348/molcells.2019.0070.

Abstract

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 R genes have been characterized from various cultivars and have greatly contributed to breeding programs to improve resistance against the rice blast pathogen Magnaporthe oryzae. The extreme diversity of R gene repertoires is thought to be a result of co-evolutionary history between rice and its pathogens including M. oryzae. Here we show that Pii is an allele of Pi5 by DNA sequence characterization and complementation analysis. Pii-1 and Pii-2 cDNAs were cloned by reverse transcription polymerase chain reaction from the Pii -carrying cultivar Fujisaka5 . The complementation test in susceptible rice cultivar Dongjin demonstrated that the rice blast resistance mediated by Pii , similar to Pi5 , requires the presence of two nucleotide-binding leucine-rich repeat genes, Pii-1 and Pii-2 . Consistent with our hypothesis that Pi5 and Pii are functionally indistinguishable, the replacement of Pii-1 by Pi5-1 and Pii-2 by Pi5-2 , respectively, does not change the level of disease resistance to M. oryzae carrying AVR-Pii. Surprisingly, Exo70F3, required for Pii-mediated resistance, is dispensable for Pi5-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.

See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6776156/

Figure 1: Comparison of Pii and Pi5 sequences

(A) Primers (black arrows) used for amplifying Pii in Fujisaka5. Grey box and black box indicate exons and introns, respectively. (B) PCR results from Fujisaka5 genomic DNA using primers shown in (A). (C) Amino acid differences between Pii (Fujisaka5) and Pi5. Letter and numbers above downward triangles indicate the amino acids in Pi5 and position corresponding to the white letters in the Pii protein schematic. Each domain in each gene is presented as rectangles. DJ, Dongjin (susceptible cultivar); CC, coiled-coil; NB, nucleotide binding site; LRR, leucine-rich repeat; CT, C-terminal domain.