Indian Journal of Virology

Several RNA viruses are known to be associated with the satellite molecules, which have no nucleotide similarity with the virus with which it is associated, known as helper virus and are dependent on the helper virus for replication, as they don't encode for the replication associated proteins. Association of satellite molecule with a DNA virus was first discovered in Tomato leaf curl virus, which is a member of the family Geminiviridae. Since then their association has been unraveled in a few other DNA viruses. The satellites are DNA β, DNA 1, DNA 2 or their recombinants, all of which are approximately 1.3 kb in size. Some of them are known to be involved in symptom modulation and very recently the only ORF of DNA β (C1) has been shown to play an important role in suppression of the inherent viral defense mechanism of plants, known as Post-transcriptional gene silencing. Cassava, Manihot esculanta is an important tuber crop, mainly cultivated in Andhra Pradesh, Kerala and Tamil Nadu. Cassava Mosaic Disease (CMD), caused by Cassava Infecting Geminiviruses (CIG), causes up to 30–40% loss in tuber production in India. Two whitefly-transmitted geminiviruses with bipartite genome, commonly known as begomoviruses have been shown to be the causative viruses for CMD in India; the Indian Cassava Mosaic Virus (ICMV) and the Sri Lankan Cassava Mosaic Virus (SLCMV). SLCMV, however is thought to have evolved from a monopartite begomovirus, by capturing the B-genome from ICMV. To check for any association of satellite molecules with CIG, Polymerase Chain Reaction (PCR)-amplification studies were performed with total DNA extracted from several mosaic affected cassava plants using the universal primers specific for DNA β. PCR products similar to the size of other DNA β were obtained, along with several smaller DNA amplified products, which possibly represent the defective forms. Further analysis of these molecules will be presented.