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Rice blast, caused by Magnaporthe oryzae (M. oryzae), is one of the most destructive diseases in cultivated rice. The Wuling Mountain Area is marked as the key area for the national prevention and control of rice blast disease in China and is the ideal area for M. oryzae research according to its unique natural condition. In this study, a simple, low-cost and effective marker system including RAPD, REMAP, rep-PCR and Avr genes was developed for genetic diversity analysis of 108 M. oryzae isolates collected from the Wuling Mountain Area during 2012-2014. The results showed significant changes in the genetic structures of M. oryzae populations over the 3 years. However, there was no remarkably simple relationship between the genetic lineages and pathotypes (physiological races) of M. oryzae. The main mechanisms of M. oryzae to overcome host genes in the natural conditions of the Wuling Mountain Area might be point mutations or small deletions of gene sequences. [ABSTRACT FROM AUTHOR]

The resistance gene Pi36 confers a stable and high level of resistance against Chinese isolates of the rice blast pathogen Magnaporthe oryzae. Quantitative real time RT-PCR was used to investigate the expression profiles of various resistance-related genes in both the Pi36/AvPi36 incompatible interactions. Among 17 members of the OsMAPK family, OsMAPK2, OsMAPK4, OsMAPK8 and OsMAPK15 were differentially expressed, as were OsWRKY30, OsWRKY32, OsWRKY64 and OsWRKY67 among the 13 OsWRKY members studied. The induction of the expression of genes from both of these families suggests that both the JA and SA pathways are involved in Pi36-mediated defence. Other genes differentially expressed included the OsbZIP transcription factors, OsNIF1 and OsNIF2, and the NPR1 homologue OsNH2, all of which were reported in the rice blast pathosystem. The involvement of these genes illustrates the complexity of the downstream signalling pathways involved in the Pi36/AvrPi36 interaction. [ABSTRACT FROM AUTHOR]