ABSTRACT
Rice tungro disease is the most important viral disease of rice in south and southeast Asia. Two viruses, Rice tungro bacilliform virus (RTBV), a DNA virus, and Rice tungro spherical virus (RTSV), an RNA virus, are found to be present in rice plants affected by tungro. Concerted efforts by several groups of researchers in India and abroad have built up a rich knowledge resource on the above viruses. A defense strategy targeting one or both the viruses promises to deliver tungro resistance in rice. Multiple approaches toward resistance against RTBV and RTSV have resulted in a number of reports indicating success in achieving this goal. Constitutive expression of viral RNAi-inducing DNA constructs strengthens the antiviral RNAi response and results in viral resistance. Similarly, expression of coat protein gene also results in resistance. Finally, manipulating expression factors required for the viral promoters have also been used to produce viral resistance in rice.
