Chrysanthemum breeding by mutation using gamma radiation

Abstract

Chrysanthemum (Dendranthema grandiflorum (Ramal.) Kitam.) is among the more popular and economically important flower. Because of an attractive flower with good form, colorful flowers, easy to grow and can bloom all year, it is often used in landscaping. Therefore, need to be breeding regularly to introduce interesting new cultivars that are attractive to consumers and are more resilient to changing climatic conditions. In this study, gamma radiation was used to induce mutations in C. morifolium. First, cuttings incubated on MS medium in tissue culture for 30 days, were irradiated with acute doses of gamma radiation at 0, 25 and 50 grays in order to select the appropriate dose that resulted in 50% lethality/50% survival (the LD50). It was found that gamma radiation at 22.5 grays gave the desired result. Cuttings of five chrysanthemum varieties, CH-09, CH-67, JP-01, JP-02 and JP-04, were irradiated at 20 grays of gamma radiation and the survival rate was 100%. The irradiated plants of cultivar CH-09 and CH-67 grew significantly taller than control plants, and irradiated plants of cultivar JP-04 had significantly more branches than others. At flowering stage, mutations were only observed in cultivar CH-09. Three new mutations were selected: 1) TISTR - TNT01, a bicolor chrysanthemum with yellow inner petals surrounded by pale pink to white outer petals, 2) TISTR - TINT02, with yellow inner petals, a middle section of light pink with yellow rimmed petals and an outer rim of light pink petals, and 3) TISTR - TINT03, which was a more distinctive tricolor flower with yellow inner petals, and a lighter yellow to white section of middle petals, surrounded by an outer rim of pink petals. These findings reinforce the notion that gamma radiation is an effective technique for inducing mutations in chrysanthemum.