Transgenic Chrysanthemums (Chrysanthemum morifolium Ramat.) Carrying both Insect and Disease Resistance

The chrysanthemum (Chrysanthemum morifolium Ramat.) is a very important ornamental flower worldwide. Damage due to both harmful insects and pathogenic microbes results in a loss of quality and leads to high control costs. To reduce the likelihood of such damage, we have developed genetically modified chrysanthemums by introducing a modified cry1Ab gene of Bacillus thuringiensis var. kurstaki HD-1 (mcbt) and a modified sarcotoxin IA gene of Sarcophaga peregrina (msar) with or without the 5'-untranslated region of the alcohol dehydrogenase gene of Arabidopsis thaliana (AtADH-5'UTR, as ADH). The leaf discs were transformed using a disarmed strain of Agrobacterium tumefaciens, EHA105, carrying the binary vectors pBIK201BPS or pBIK201ABPS, which contain the mcbt and msar genes. The mcbt and msar genes were detected in all regenerated plantlets by Southern blot analysis, with a transformation frequency of 6.8%. Northern blot analysis revealed that the amount of the mcbt transcription was influenced by the transgene copy number in the genetically modified (GM) chrysanthemum. However, that of the msar transcript was influenced by the presence of the HSP terminator, regardless of the gene copy number. The GM chrysanthemums accumulated more than 1.31 mu g of Cry1Ab per mg of total soluble protein and showed a strong resistance against 4 species of lepidopteran larvae (Helicoverpa armigera and others). All larvae died during the first instar stage. A strong resistance against white rust by Puccinia horiana was observed especially in the ADH::msar-transgenic chrysanthemum in which the expression level of sarcotoxin IA peptide was more than 19.5 mu g per g fresh weight of leaves. These GM chrysanthemums will be useful in reducing control costs for lepidopteran insects and white rust disease.