Antagonistic effect of p-aminobenzoate or folate on asulam [methyl (4-aminobenzensulphonyl carbamate)] inhibition of carrot suspension cultures

Abstract

Growth inhibition of carrot cell suspension cultures by methyl (4-aminobenzensulfonyl carbamate) (asulam) can be reversed by adding p-aminobenzoic acid (PABA) or folic acid to the medium. Double reciprocal plots of growth and antagonist concentration indicate the inhibition to be competitive. The reversal by PABA and folic acid results from the structural relationship of asulam and PABA and the substituted sulfonamides. Components of C 1 metabolism that were ineffective in reversing asulam inhibition included: adenine, thymine, dimethyl glycine, sarcosine, choline, glycine, serine, ethanolamine, methionine, formylmethionine and pantothenic acid.