Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi-110012
National Symposium on “Plant Pathology in the Changing Global Scenario” held at National Bureau of Plant Genetic Resources, New Delhi on February 27–28, 2009
Papaya production in India is decimated by Papaya ringspot (PRSV) and Papaya leaf curl (PLCV) viruses. The most effective way to contain the losses caused by these viruses is through growing resistant plants. In the absence of desired level of resistance in papaya cultivars, there is a need to either complement or enhance natural resistance with transgene-mediated resistance. Transgenic papaya against PRSV has been developed using coat protein mediated resistance (CPMR) strategy and cultivars like Rainbow and Sun UP have been commercially released in Hawaii (USA). Similar approach has been used by several laboratories in India including IARI to develop virus resistance transgenic papaya (VRTP). Genetic diversity within PRSV isolates originating from different locations has been determined. PRSV isolates varied in CP length (275–289 aa) and amino acid sequences (up to 23%). Maximum heterogeneity was observed in southern isolates (up to 23%), followed by central (up to 11%), eastern and northern (up to 10%) and western (up to 7%) isolates. PRSV isolates were grouped into three clusters and no relationship between diversity and geographical origin of the isolates was observed. To develop VRTP, constructs with full CP gene (850bp) in sense and antisense orientation, truncated CP gene (410bp) and inverted repeat CP gene (500bp) were used for papaya transformation. Besides, a dual construct with truncated CP and replicase gene of PRSV and PLCV, respectively was developed to confer resistance against both the viruses.
