Polymorphism and resistance spectrum to Magnaporthe oryzae analysis of Pi-d2 haplotypes in rice (Oryza sativa L.) resource from Yunnan province of China

Abstract

Abstract Pi-d2, which encodes a potential serine-threonine receptor-like kinase (RLK) membrane-spanning protein consisting of 825 amino acids, confers resistance to Magnaporthe oryzae strain ZB15 via an unidentified recognition mechanism. In this study, the Pid2 alleles of 303 rice (O. sativa) varieties from China's Yunnan region were amplified and sequenced in order to produce 24 haplotypes and 16 translation variants. Six of twenty-four alleles possessing the resistant site at the 441st amino acid were chosen for evaluating blast resistance by transforming into the blast-vulnerable rice variety Nipponbare. After being infected with 11 strains of M. oryzae, all transgenic lines exhibited resistance to ZB-15, whereas resistance to other strains varied. Notably, Pi-d2_H23 and Pi-d2_H24 exhibited resistance to all M. oryzae strains tested, indicating that these two alleles may have a broader resistance spectrum to M. oryzae. Alignment of these alleles’ amino acid sequences revealed that the differences in blast resistance spectra were primarily related to the amino acids present in the PAN domain at position 363 (valine/alanine). These findings suggested that the two extracellular signal recognition domains of PI-D2, B-lectin and PAN, may play a role in the identification of M. oryzae effectors. The present results provide insight into the mechanism of interaction between RLKs and M. oryzae.