Detoxication of phenol in annual plant seedlings

Transformation of phenol (14C6H5OH) penetrating through the roots of mung bean (Phaseolus aureus) and wheat (Triticum vulgare) sterile seedlings has been studied. Phenol was coupled to low-molecular-weight peptides, producing phenol-peptide conjugates. Hydrolytic cleavage of the conjugates liberated initial labeled phenol and some unlabeled amino acids. Phenol- glutathione and phenol-homoglutathione were not found among the peptide conjugates. It is suggested that the conjugation is carried out via the hydroxyl group of phenol and functional groups of peptides. Conjugation with low-molecular-weight peptides is considered to be the main pathway for phenol detoxication, since about 60% of phenol absorbed by plants conjugates with peptides. In the plants treated with phenol, the amount of low-molecular-weight peptides is increased. The increase in peptide synthesis in plants seems to be induced by the penetration of toxic phenol molecules into the cell. The small amount of phenol molecules assimilated through roots is transformed via aromatic ring cleavage and bibasic carbonic acid formation.