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Functional Analysis of Pid3-A4, an Ortholog of Rice Blast Resistance Gene Pid3 Revealed by Allele Mining in Common Wild Rice

First, eighth, ninth, and fourteenth authors: Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, China; first, second, third, fourth, fifth, sixth, seventh, tenth, twelfth, and thirteenth authors: State Key Laboratory of Plant Genomics and National Plant Gene Research Center (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101; second and eleventh authors: National Engineering Laboratory for Tree Breeding, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of State Forestry Administration, Beijing Forestry University, Beijing 100083; and fifth author: Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 101300.

The rice blast resistance gene Pid3 encodes a nucleotide-binding-site leucine-rich repeat (NBS-LRR) protein. This gene was cloned from the rice ‘Digu’ (indica) by performing a genome-wide comparison of the NBS-LRR gene family between two genome-sequenced varieties, ‘9311’ (indica) and ‘Nipponbare’ (japonica). In this study, we performed functional analysis of Pid3-A4, an ortholog of Pid3 revealed by allele mining in the common wild rice A4 (Oryza rufipogon). The predicted protein encoded by Pid3-A4 shares 99.03% sequence identity with Pid3, with only nine amino-acid substitutions. In wild rice plants, Pid3-A4 is constitutively expressed, and its expression is not induced by Magnaporthe oryzae isolate Zhong-10-8-14 infection. Importantly, in transgenic plants, Pid3-A4, as compared with Pid3, displays a distinct resistance spectrum to a set of M. oryzae isolates, including those that prevail in the rice fields of Sichuan Province. Therefore, Pid3-A4 should be quite useful for the breeding of rice blast resistance, especially in southwestern China.

Additional keywords: broad-spectrum resistance.