PRODUCTION OF THIOPHENES IN CALLI AND SUSPENSION-CULTURES OF TAGETES-PATULA L AS INFLUENCED BY LIGHT DARK SUCCESSION

HPTLC-densitometry was used to evaluate thiophene accumulation in leaf calli and cell suspension of Tagetes patula. Calli obtained from 7-8 weeks old leaves were subcultured in supplemented MS for many months. The secondary calli showed 4 to 6-fold higher fresh weight increment i n 2 weeks while the tertiary ones only doubled their weight in the sam e period. A considerable increase of thiophene production (about 16.5 -fold) was obtained growing calli under successive light/dark periods. Repeated subculturing of callus tissues resulted in a slow decline of the thiophene yield. Under the same conditions, cell suspension cultu res did not exhibit an appreciable increment in thiophene content whic h decreased with subculturing.