Production of intergeneric somatic hybrids of chrysanthemum [ Dendranthema × grandiflorum (Ramat.) Kitamura] and wormwood ( Artemisia sieversiana J. F. Ehrh. ex. Willd) with rust ( Puccinia horiana Henning) resistance by electrofusion of protoplasts

We produced intergeneric somatic hybrids between chrysanthemum [ Dendranthema× grandiflorum (Ramat.) Kitamura] and wormwood ( Artemisia sieversiana J. F. Ehrh. ex. Willd) by electrofusion of mesophyll protoplasts. Chrysanthemum protoplasts were inactivated with iodoacetamide for 15 min at 5 °C and electrofused with wormwood protoplasts. The fused cells were cultured on MS basal medium containing 1 mg/l naphthaleneacetic acid (NAA) and 1 mg/l 6-benzylaminopurine (BAP) to regenerate somatic hybrid chrysanthemum plants. The 3,864 calli that appeared produced 1,342 plantlets, all of which had RFLP bands specific for both chrysanthemum and wormwood. The chromosome numbers of the somatic hybrid plants were 64–72, indicating that chromosomes were eliminated during cell division or plant regeneration. The 1,342 plantlets were grown in pots in a greenhouse, and 23 of the plants flowered. These 23 somatic hybrid plants were examined for rust ( Puccinia horiana Henning) resistance and abnormal morphology in comparison with the parent plants. The somatic hybrid plants were more resistant to rust than chrysanthemum, and the disease spots that appeared had diameters of only 1–2 mm, and they have not expanded any more. The characteristics of the flowers such as flower shapes and colors of their flowers differed from those of the parent plants, and these somatic hybrid plants were possibly male-sterile. Although the rooting ability of the somatic hybrid plants was poor, the somatic hybrid plants had agronomical treat, demonstrating the efficiency of this technique in transferring agronomically useful genes from cross-incompatible species or genera.