| Neonicotinoid pesticides were such kind of insecticide which had the suction of strong, broad spectrum, low resistance for pests, and was safe for people, animals and plants. Especially imidacloprid was widely used in tea plantation of China, and it had a good effect on green leafhoppert. In addition to photolysis and hydrolysis,these pesticides could be lead to the more toxic metabolites after absorbed quickly by plants, tend to remain in the crops or the environment, and the metabolites were considered as the pollutants of emerging food and environmental.So, people had taken growing emphasis on safety issues of pesticide metabolites.Due to the complexity of matrix components in tea, it was difficult to confirm the trace of pesticide metabolites because of the influence of the matrix, whereas the vitro system, particularly the cell suspension culture, was the good means for the study of pesticide metabolism.In this paper, the research was aimed to establish research platform of tea leaf cells of pesticide metabolism. The suspension system of tea leaf cell was established, preliminary researched the situation that how imidacloprid metabolized in the suspension system of tea leaf cells, and the degradation products of imidacloprid were identified, expecting to identify degradation products of imidacloprid in the tea leaves and figured out the mechanism of degradation products. The main results were as follow:1. Treated Longjing 43 tea leaf as the experimental materials, optimization of its first generation of callus induction conditions were explored. The results showed that the suitable sterilizing conditions for explant was 75% alcohol 10 s+0.1% mercuric chloride 10 min, the plant growth regulator was KT (0.5 mg/L)+2,4-D (2.0 mg/L); pH 5.8; spring was suitable season for tea leaves callus induction.2. The conditions of Longjing 43 tea leaf callus subculture culture were optimized. Compared growth status of callus and the average growth rate by using different combinations of plant growth regulators, ultimately the most appropriate subculture combination of plant growth regulator was KT (0.1 mg/L)+2,4-D (0.5 mg/L); compared growth state of callus,21 days was optimal growth cycle for subculture culture; compared different inoculum for tea leaf callus subculture culture,following the impact of culture efficiency, and when inoculum was at around 1.0 g, the callus could grow rapidly; observed growth status of under light and dark conditions, callus of tea grew well and had the loose texture in the dark.3. The suspension cells system of Longjing 43 tea leaf was established. The results showed that, B5 was more suitable than MS as the basic medium for suspension cell culture of Longjing 43 leaves callus; the appropriate speed was 120 r/min; other culture conditions were the same as subculture culture of callus.4. The imidacloprid was photodegradated at the light intensity of 80001nx in met hanol and pure water. The result showed that the rule of its degradation in two kin ds of solvent was in line with a kinetic equation (r2 was 0.9209 and 0.9179 respect ively); Half-life of photolysis in methanol was 3.80 h, while in water its Half-life was 7.00 h. In methanol the rate of photolysis was obviously faster than that in w ater; 1-[(6-chloropyridin-3-yl)methyl]imidazolidin-2-one,l-[(6-chloropyridin-3-yl)methyl] imidazolidin-2-imine were identified as the main products by HPLC-MS.5. The metabolism of imidacloprid in tea leaf cells of suspension system and its metabolites was investigated. The average metabolic rate of imidacloprid in tea leaf cells of suspension system was 47.54%. Metabolite of imidacloprid could be identified as 1-[(6-chloropyridin-3-yl)methyl]imidazolidin-2-one by HPLC-MS; further evaluation for degradation products of imidacloprid and its residues on crops was necessary. |
