Resistance To Insect Of Natural Taxus Cuspidata

Taxus cuspidate is a tertiary relic species, mostly distributed in the northern of China, it is also class I national protected and endangered species. All world focus on the compound Taxol which has high anticancer activity. Recent years, most researches were about mechanism of anticancer and how to plant Taxus by manpower that in order to get more Taxol. But the yew trees in their wild state in northeast of China are rarely threatened by insects and diseases.Research in its defense mechanism is few, researches in the field of chemical ecology and plant physiology has no precedent. The article studied the Taxus in Muling Nature Reserve of Heilongjiang Province from two parts, antifeedant activity of the secondary metabolic compounds of Taxus against Lymantria dispar L.larva and the differences in gender, diameter, leaf age and seasonal variation of the defense proteins. The results show as follows,1. Antifeedant activity of the secondary metabolic compounds of Taxus against Lymantria dispar L.larvaTo explore reasons under this phenomenon, Lymantria dispar L.larva's choice and no-choice antifeedant activity of Cephalomannine and Taxol (both of which are the secondary metabolic compounds of yew) had been studied by leaf disc tests. Results showed that Lymantria dispar L.larva had antifeedant activity of both Cephalomannine and Taxol. Meanwhile, Cephalomannine with higher concentration demostrates an increasing antifeeding rate. More specifically, when concentration was 2 mg/ml, the choice and no-choice antifeedant activity were 67.46% and 72.37%, respectively. However, Taxol with lower concentration present better antifeedant activity towards Lymantria dispar L.larva. For instance, the no-choice antifeeding rate was 87.18% when the concentration was 0.25 mg/ml while the choice antifeeding activity were divided into two situations. When the concentration was below 1 mg/ml, choice antifeeding activity tend to reduce as longer time Lymantria dispar L.larva been treated whilst the activity was strengthened by time when concentration was approximate or above 1 mg/ml, which could reach 74.95% after 48 hours. To conclude, Taxol, rather than Cephalomannine, shows stronger antifeedant activity towards Lymantria dispar L.larva.2. Activities of the Defense Protain in Leaves of Taxus Under Gender Diameter and Leaf ageIn order to investigate the relationship between gender stand age and leaf age in yew and its constitutive defense,this study measured the activities of PAL,PPO,POD,CAT,TI and CI in female and male leaves of yew with two stand age grades and three leaf age grades respectively.The results showed that the activities of PAL,PPO,POD,TI and CI were all significant differences under gender stand age and leaf age(P<0.05). Furthermore, the activities of TI and CI in male leaves significantly higher than those in female(P<0.05); the activities of PAL,PPO and POD in old age significantly higher than those in young age(P<0.05);the activity of TI in young leaf age significantly higher than it in old leaf age,the activity of PAL is on the contrary.The results indicated that gender and stand age in yew had the direct impact on constitutive defenses.3. The seasonal variations of Defense Protein activities in Leaves of TaxusThe results showed that activity of PPO,PAL,CAT,TI,CI in leaves of Taxus all presented a trend of July>September>May, activity of POD in leaves of Taxus presented a trend of September> July>May and significant difference among different months. The male and the female in the same trend.The results evidented that the secondary metabolic compounds of Taxus have high antifeedant activity against Lymantria dispar L.larva; gender,diameter,leaf age and seasonal variations all have significant effect to defense protein in leaves of Taxus. The paper was the first and systematic study, which research the Antifeedant activity of the secondary metabolic compounds of Taxus against Lymantria dispar L.larva and the connection between gender, diameter, leaf age and defense protein, the results will provide theory evidence for protection of natural Taxus and plantation in manpower. Moreover research of antifeedant by the secondary metabolic compounds could provide a new way for the management of inserts and the production of new botanical pesticide.