Biosynthesis of thiophenes in cell cultures of Tagetes patula

Cell cultures of Tagetes patula incorporate 35S-label from methionine, cysteine, sulfide and sulfate into thiophenes, a group of heterocyclic biocides. In time course studies up to 4% of the total 35S-label from [35S] sulfate was incorporated into thiophenes within 24 hours. The bulk of the radioactivity (>80%) in thiophenes was observed in 5-(4-hydroxy-1-butinyl)-2,2'-bithiophene (BBTOH) while the rest was in 5-(4-acetoxy-1-butinyl)-2-2' -bithiophene (BBTOAc) and 5-(but-3-ene-1-ynyl)-2,2'-bithiophene. Pulse-chase experiments, involving a 24 h-pulse with [35S] sulfate, showed a constant level of radioactivity in BBT during the chase period while there was a shift in 35S-label from BBTOH to BBTOAc. Also, the specific activity of BBT was always lower than that of the other two while the specific activity of BBTOH was higher than that of BBTOAc. These results indicate that (a) BBT is not an obligatory intermediate in the biosynthesis of BBTOH and BBTOAc and (b) BBTOH may be the precursor for BBTOAc