Comparative metabolite profiling of the insecticide thiamethoxam in plant and cell suspension culture of tomato.
The metabolism of thiamethoxam [(EZ)-3-(2-chloro-1,3-thiazol-5-yl-methyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene (nitro) amine] was investigated in whole plant, callus, and heterotrophic cell suspension culture of aseptically and field grown tomato (Lycopersicon esculentum Mill.) plants. The structure of the metabolites was elucidated by chromatographic (HPLC) and spectroscopic (IR, NMR, and MS) methods. Thiamethoxam metabolism proceeded by the formation of a urea derivative, a nitroso product, and nitro guanidine. Both urea and nitro guanidine metabolites further degraded in plants, and a mechanism has been proposed. In the plant, organ-specific differences in thiamethoxam metabolism were observed. Only one metabolite was formed in whole plant against four in callus and eight metabolites in cell suspension culture under aseptic conditions. Out of six metabolites of thiamethoxam in tomato fruits in field conditions, five were similar to those formed in the cell suspension culture. In the cell suspension culture, thiamethoxam degraded to maximum metabolites within 72 h, whereas in plants, such extensive conversion could only be observed after 10 days.
Karmakar
Rajib
R
Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi-110012, India.
Bhattacharya
Ramcharan
R
Kulshrestha
Gita
G
D002478:Cells, Cultured; D005638:Fruit / Q000737:chemistry / Q000378:metabolism; D006146:Guanidines / Q000378:metabolism; D007306:Insecticides / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000737:chemistry / Q000378:metabolism*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000378:metabolism*; D009603:Nitroso Compounds / Q000378:metabolism; D010078:Oxazines / Q000378:metabolism*; D000077922:Thiamethoxam; D013844:Thiazoles / Q000378:metabolism*; D014508:Urea / Q000378:metabolism
D006146:Guanidines; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D009603:Nitroso Compounds; D010078:Oxazines; D013844:Thiazoles; D000077922:Thiamethoxam; D014508:Urea; C056179:nitroguanidine