Agrobacterium Mediated Genetic Transformation of Chrysanthemum (Dendranthema grandiflora Tzvelev) with Rice Chitinase Gene for Improved Resistance Against Septoria obesa

Chrysanthemum is an important commercial cut flower crop. It is severely infected by leaf spot disease caused by Septoria obesa resulting in huge yield loss. A simple and efficient protocol for the Agrobacterium mediated transformation of chrysanthemum cv., Snow Ball has been developed. The initiation of direct shoots was achieved from four week old internodal segments maintained on MS medium supplemented with 2 mg L-1 6-benzyladenine (BA) and 0.25 mg L-1 naphthaleneacetic acid (NAA). To develop transgenic chrysanthemum resistant to fungal diseases, an attempt was made to transfer rice chitinase gene in chrysanthemum cv. Snow Ball. The rice chitinase gene harboured in the plasmid pCAMBIA-ubi-chiII (13.8 kb) was delivered via the Agrobacterium-mediated method to the internodal segments followed by subsequent development of complete plants on selection medium containing 10 mg L-1 hygromycin used as selective agent. Four independent putative transformed plants were recovered with stringent selection pressure. Molecular analysis of these plants confirmed the integration of chiII gene in three transformed plants. Transformation frequency of 2.2% was obtained. No plant was classified as resistant, one plant showed slight symptoms whereas two plants exhibited moderate symptoms when the transformants were tested with spore suspension of Septoria obesa under glasshouse conditions.