Anti-TMVActivity of Atisine-type Diterpene Alkaloids in Spiraea Japonica Associates with Down-Regulating the Expression of TMV Coat Protein

Four atisine-type diterpene alkaloids, including hsp-X40, hsp-X35, hsp-X31 and hsp-X26, were derivatives of diterpenes isolated from the ethanol extract of Spiraea japonica and then their chemical structures were determined with spectroscopy techniques. The result indicated that four compounds at a concentration of 100µg/mL can inhibit the infection of TMV to tobacco through in vivo curative activity, with the curative rate of 55.4±1.5% of hsp-X26, 53.2±1.9% of hsp-X31, 58.1± 2.0% of hsp-X35, 60.3±1.2% of hsp-X40, which was lower (p< 0.05) than that of the positive control Ningnanmycin (55.2±1.9%). However, the four compounds have not shown a better protective effect for tobacco against the TMV infection. The compound hsp-x40 with the diterpene amino acid ester group exhibited its IC50 value was 76.7 ± 2.4 μg/mL, suggesting that diterpene amino acid ester group may be as the important functional group for the anti-TMV activity of atisine-type diterpene alkaloids. The molecular experimental results showed that four active compounds can down-regulate the expression of TMV coat protein, indicating that the anti-TMV activity of atisine-type diterpene alkaloids in spiraea japonica associates with down-regulating the expression of TMV coat protein.