Expression profiles of OsNramp6 transcript variants involving in Magnaporthe oryzae resistance and non-resistance of Vietnamese rice cultivars

Magnaporthe oryzae is the causal agent of rice blast disease resulting in yield losses in rice-growing regions worldwide, particularly in Vietnam. Up-regulation of osa-miR7695 was observed in blast resistant rice cultivars in comparison with blast non-resistant rice cultivars. The OsNramp6 gene is a target for osa-miR7695 , and considered a factor involved in rice immunity but scant evidence has demonstrated systematic expression profiles of OsNramp6 transcript variants involving M. oryzae susceptibility and resistance of rice plants. In this study, a real-time qPCR (qRT-PCR) approach was used to evaluate the expression levels of eight OsNramp6 transcript variants in various Vietnamese rice cultivars. Results indicated that OsNramp6.1 and OsNramp6.4 transcript variants showed decreased expression levels at 24 hpi in M. oryzae resistant rice cultivars and vice versa in the rice group of M. oryzae resistance, suggesting that both could be used as potential markers for discrimination between blast resistant and non-resistant Vietnamese rice cultivars. Identification of potential microRNAs in rice that contribute to the regulation of OsNramp6 transcripts-mediated facilitation of infection by M. oryzae has still to be confirmed for elucidating their roles in rice immunity against M. oryzae .