ZR2010CM044), the National Basic Research Program of China (973 Program, Grant No. 2009CB118602), and State Key Laboratory of Crop Biology (Grant No. 2012KF01) of Shandong Agricultural University, Tai’an, Shandong, China. “
“Rice blast disease, caused by the filamentous ascomycete fungus Magnaporthe oryzae (formerly Magnaporthe grisea), is one of the most destructive diseases of rice worldwide. The fungus can also cause severe infections in wheat [1]. Avirulence (AVR) genes in M. Alisertib clinical trial oryzae are known to be highly unstable [2] owing to

the presence of a large number of active transposable elements that can shape the evolution and adaptation of the fungus [3]. To date, seven race-specific avirulence genes, AVR-Pita1, AVR1-CO39, ACE1, AVR-Pizt, AVR-Pik, AVR-Pii and AVR-Pia, have been molecularly characterized. ACE1 has been found among rice isolates and can be used to induce avirulence [4]. It encodes a putative polyketide synthase fused to a non-ribosomal peptide synthetase determining the specificity of Pi33 [4]. AVR1-CO39, an isolate of M. grisea from weeping lovegrass, encodes a signal that triggers a strong defense response in the rice cultivar CO39, which Cytoskeletal Signaling inhibitor carries the corresponding resistance (R) gene [5]. AVR-Pizt, recognized by the R gene Piz-t, can suppress BAX-mediated

programmed cell death in Nicotiana benthamiana, suggesting a mechanism by which AVR-Pizt may confer virulence on M. oryzae [6]. The remaining three Tacrolimus (FK506) AVR genes of M. oryzae were novel

genes [7]. In contrast, abundant major and minor blast resistance (R) genes have been identified in rice germplasm worldwide [8]. Thus far 16 major and two minor blast R genes have been cloned, most of which encode NBS type R proteins [9]. Understanding R–AVR gene interaction specificity is important for the development of effective strategies to manage rice blast disease. AVR-Pita determines the efficacy of the R gene Pi-ta [10]. The genes Pi-ta and AVR-Pita are the first R/AVR gene pair characterized in the rice blast system. AVR-Pita is located in the telomeric region of chromosome three of M. oryzae, and was cloned from a Chinese isolate, O-137 [10]. AVR-Pita was renamed AVR-Pita1 following the discovery that it has several family members in the Magnaporthe species [11]. AVR-Pita1 encodes a protein with 223 amino acids with properties highly similar to those of a metalloprotease [10]. AVR-Pita716 codes for a putative product that was predicted to be an elicitor that binds to Pi-ta directly inside plant cells, triggering an effective blast resistance response [12] and [13]. Other biological functions of AVR-Pita in M. oryzae remain unclear; however, it was predicted to be involved in the early stages of pathogenesis [10]. Recently, AVR-Pita1 was shown to accumulate in the biotrophic interfacial complex (BIC), raising the possibility that AVR-Pita1 prepares rice cells for subsequent fungal entry and biotrophic growth [14]. A recent analysis of strains of M.