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Congenial In Vitro γ-Ray Induced Mutagenesis Underlying the Diverse Array of Petal Colours in Chrysanthemum (Dendranthemum grandiflorum kitam) cv. “Candid”
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2  2Astrophysical Sciences Division, Nuclear Research Laboratory, Bhabha Atomic Research Centre, Srinagar, India


Chrysanthemum (Dendranthemum grandiflorum kitam.) is a leading flower with applied value worldwide. The flower color of ancestral species is limited to yellow, pink, and white, and is derived from carotenoids, anthocyanins, and the absence of both pigments, respectively. A wide range of flower colors, including purplish-red, orange, red, and dark red, has been developed by increasing the range of pigment content or the combination of both pigments. Recently, green-flowered cultivars containing chlorophylls in their ray petals have been produced, and have gained popularity. In addition, blue/violet flowers have been developed using a transgenic approach. Flower color is an important trait that influences the commercial value of chrysanthemum cultivars. Developing new chrysanthemum cultivars with novel characteristics such as new flower colors in a time- and cost-efficient manner is the ultimate goal for breeders. Understanding the molecular mechanisms that regulate flower pigmentation may provide important implications for the rationale manipulation of flower color. To generate diverse array of flower colour mutants in chrysanthemum cv. “Candid” through mutagenesis, in vitro grown micro shoots were exposed to 10, 20, 30 and 40 Gy gamma irradiation at 100 Gy per minute and were evaluated for different parameters. The rhizogenesis parameters decreased with the increase in irradiation dose from 0 Gy to 40 Gy, while as, 10 Gy dose proved to record minimum decline as compared to the control. Survival, leaf size and number of leaves plant-1 after 8th week interval also decreased with the increasing trend of gamma irradiation dose but recorded minimum decline in plants developed from shoots irradiated with 10 Gy gamma irradiation dose with respect to the control. Apparently minimum delay in number of days to floral bud appearance took under 10 Gy as compared to control. Highest number of flower colour mutants were recorded under 10 Gy (light pink, orange pink,white and yellow). Amountable mutation frequency on the basis of flower colour was desirable in plants irradiated with least dose of 10 Gy

Keywords: Chrysanthemum;Mutagenesis; Gamma Irradiation; Mutants