ISHS Acta Horticulturae 714: XXII International Eucarpia Symposium, Section Ornamentals, Breeding for Beauty
INSECT RESISTANT TRANSGENIC CHRYSANTHEMUM [DENDRANTHEMA X GRANDIFLORUM (RAMAT.) KITAMURA] |
| Authors: | H. Shinoyama, A. Mochizuki |
| Keywords: | gene transformation, resistance to lepidopteran insects, modified cry1Ab gene, Helicoverpa armigera, Spodoptera litura |
| Abstract:
Chrysanthemums [Dendranthema x grandiflorum (Ramat.) Kitamura] are among the most important ornamental flowers worldwide, and insect damage by lepidopteran pests is a very serious problem in cultivation, resulting in reduced quality and high pesticide costs. To reduce such damage, we introduced a modified endotoxin gene cry1Ab of Bacillus thuringiensis var. kurstaki HD-1 (named mcbt), into five popular chrysanthemum cultivars. Leaf discs were co-cultured with Rhizobium and thereafter cultured on callus-induction medium containing G418 for selection. The expression level of the insecticidal crystal protein (ICP) Cry1Ab (molecular weight 58 kDa) ranged from 9.3 ng to 82.5 ng per 50 μg of total soluble protein (from 0.019 to 0.165% of the total protein) in mcbt-transformants. An insect bioassay was conducted using larvae of the oriental tobacco budworm (Helicoverpa armigera) and the common cutworm (Spodoptera litura). All larvae of H. armigera died during the first instar when they were supplied with leaves of the mcbt-transformants whose expression level of Cry1Ab ICP exceeded 48.9 ng per 50 μg of total soluble protein. Leaf area consumed by five larvae was under 1%. All larvae of S. litura died during the second instar when they were provided with the leaves of the mcbt-transformants whose expression level of Cry1Ab ICP exceeded 62.3 ng per 50 μg of total soluble protein. Leaf area consumed by five larvae was 3.5 to 5.2%. The transformants have the potential to reduce labor and/or the costs for lepidopteran insect control. Moreover health risks to cultivators and environmental pollution caused by pesticides may also be reduced. | |
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