Genetic transformation and development of Cucumber mosaic virus resistant transgenic plants of Chrysanthemum morifolium cv. Kundan

Chrysanthemum morifolium Ramat. cv. Kundan has been found susceptible to infections of Cucumber mosaic virus (CMV) which drastically affects the quality and quantity of blooms and poses significant constraints in commercial cultivation of chrysanthemum in India. Therefore, development of inbuilt resistance in C. morifolium against CMV seems to be essential. Agrobacterium-mediated transformation of petiole explants of C. morifolium was attempted using pRoK2 binary vector harbouring coat protein (CP) gene of CMV under the control of CaMV 35S promoter. A total of 257 explants were transformed and 73 putative transgenic plants from seven independent co-cultivation events were obtained with ∼6% transformation efficiency. Molecular analysis of these plants confirmed the successful integration of CP transgene in 63% plants, of which 12.3% plants were able to transcript and translate the transgene. Expression of coat protein did not evoke any abnormal phenotype. Transgenic plants showed delayed resistance when challenged by CMV-chrysanthemum strain which produced good quality blooms as compared to the susceptible ones.