Central Tuber Crops Research Institute, Thiruvananthpuram-695017, India.
Cassava (Manihot esculenta Crantz.) is an important staple food and industrial crop in more than 80 countries. It is being grown in India for more than a century mostly in Kerala, Tamil Nadu, Andhra Pradesh, Maharashtra and few North Eastern states. Among the various biotic factors which affect cassava, Indian cassava mosaic disease (ICMD) has emerged as one of the serious limiting factors and causing an yield loss ranging from 20% to 88% in different cultivars. This disease is caused by Indian Cassava Mosaic Virus (ICMV) and Sri Lankan Cassava Mosaic Virus (SLCMV). Resistant source to this disease is not available in the global cassava germplasm. In the present study, Replicase gene (AC 1) of ICMV was cloned in pGEM-T Easy vector as a candidate gene for developing pathogen derived resistance against ICMV infection. Sequencing of AC1 gene showed that it had 1055 nucleotides, which encoded for 351 amino acids. Full length AC1 gene constructs were made in pBin19 plant transformation vector and mobilized to Agrobacterium tumefaciens strain LBA4404. Through Agrobacterium mediated gene transfer method, these constructs were introduced into cassava hybrid H226 using cotyledons as explants. Transformants were selected by increasing the concentration of paramomycin from 10mg 1-1 to 25mg 1-1. Analysis of incorporation of AC1 gene in transgenic cassava lines were confirmed through PCR using nptII and AC1 primers and Southern analysis.
