GC-MS studies reveal stimulated pesticide detoxification by brassinolide application in Brassica juncea L. plants

Imidacloprid (IMI) is a commonly used pesticide against aphids and accumulates in plant parts, maximum in leaves. Present study was conducted to check the efficiency of seed pre-soaking with 24-epibrassinolide (24-EBL) for reduction of this pesticide in the leaves of Brassica juncea L. plants raised from 24-EBL pre-soaked seeds and grown in soils supplemented with IMI. Leaves were analyzed for IMI residues using gas chromatography-mass spectrometry (GC-MS). Activities of guaiacol peroxidase (POD), glutathione reductase (GR), and glutathione S-transferase (GST), and glutathione (GSH) content were determined by spectrophotometry. Soil containing 350 mg IMI/kilogram soil resulted in 88.66 μg/g fresh weight (FW) of IMI residue in the leaves, which was maximum decrease to 35.31 μg/g FW (60.17 %), when seeds were pre-soaked in 100 nM 24-EBL. In this treatment (350 mg IMI/kilogram soil + 100 nM 24-EBL), GSH content, GR, POD, and GST activities were increased by 42.30, 34.5, 20.5, and 13.4 %, respectively, as compared to plants grown in soils amended with 350 mg IMI/kilogram soil.