Relationship between Resistance to Rice necrosis mosaic virus and the Expression Levels of Rice RNA-dependent RNA polymerase 6 (OsRDR6) in Various Rice Cultivars

Abstract

Rice necrosis mosaic virus (RNMV) is a fungus-transmitted bymovirus that leads to losses in rice yield. This research tested ten rice cultivars (cvs) with different levels of resistance to RNMV. The lowest levels of RNMV RNA were found in two high-resistance cvs; the highest levels were found in the two low-resistance cvs. The RNA-dependent RNA polymerase 6 gene in rice (OsRDR6) was found to be the most highly expressed in two high-resistance cvs and the least expressed in two low-resistance cvs although its basal level of constitutive expression was similar among cvs. Plant growth and yields were also tested. The extent of RNMV RNA accumulation affected plant height, panicle/tiller numbers, and seed weight. The RNMV induced OsRDR6 expression level in the rest of cvs was more or less inversely correlated to RNMV RNA accumulation. The observed results suggest a close relationship between RNMV resistance and RNMV induced OsRDR6 expression level in these cvs.