RNAi-mediated down regulation of BADH2 gene for expression of 2-acetyl-1-pyrroline in non-scented indica rice IR-64 (Oryza sativa L.).

2-acetyl-1-pyrroline (2AP) is a principal aroma compound in scented rice and a mutation in betaine aldehyde dehydrogenase 2 (OsBADH2) is responsible aroma in scented rice. The present study was aimed at inducing 2AP production in non-scented indica rice cultivar IR-64 by silencing OsBADH2 via RNAi technique. A vector pBSK was used for the construction of RNAi cassette and pRI101ON as a binary vector. Agrobacterium (GV3101)-mediated transformation was done using embryogenic calli of IR-64. The resultant transgenic lines showed up to 14-fold reduction in expression of OsBADH2 gene and 50% inhibition in enzyme activity. Gas chromatography (GC-MS) analyses showed a significant amount of 2AP production in RNAi callus, leaves, and seeds of IR-64. A total 39 volatile compounds were identified from the control and RNAi seeds of IR-64. Among them, octanal and 2-pentylfuron were found to be increased (30-40%) in RNAi seeds of IR-64. The content of precursors, proline, and methylglyoxal increased substantially, whereas GABA content reduced up to 25% in transgenic IR-64 lines. The study demonstrated that RNAi approach could be successfully used for imparting pleasant aroma character in non-scented indica rice cultivars.