Identification of rice blast resistance genes using international monogenic differentials

Rice blast disease, caused by the fungal pathogen Magnaporthe oryzae, is one of the most devastating diseases of rice that severely affects crop production in the Jilin Province, Northeast China, where temperate japonica rice is primarily grown. In the following study, 44 representative local blast isolates were inoculated onto international monogenic differentials carrying 24 major blast resistance genes – Pia, Pib, Pii, Pik, Pik-h, Pik-m, Pik-p, Pik-s, Pish, Pit, Pita, Pita-2, Piz, Piz-t, Pi1, Piz-5, Pi3, Pi5(t), Pi7(t), Pi9, Pil2(t), Pi11(t), Pi19, and Pi20 – and the susceptible recurrent parent, Lijiangxintuanheigu (LTH), under greenhouse conditions. The percentage of virulent reactions of monogenic lines to the 44 isolates was found ranging from 8.3% to 79.2%. LTH was susceptible to all 44 isolates. All 24 monogenic differential lines were resistant to at least 4 isolates of M. oryzae, and the frequency of resistant reactions of the monogenic lines carrying Pi9, Pi19, Piz, Piz-5, Piz-t, Pi12(t), Pi5(t), and Pik-h were 94.2%, 84.1%, 81.8%, 81.8%, 79.5%, 72.7%, 68.2%, and 68.2%, respectively. These results suggest that Pi9, Pi19, Piz, Piz-5, Piz-t, Pi12(t), Pi5(t) and Pik-h may be important R genes for preventing blast disease. Based on these data, a useful strategy for managing rice blast disease by stacking pyramiding blast R genes against pathogenic M. oryzae isolates in the Jilin Province was proposed.