Distribution and Accumulation of Thiophenes in Plants and Calli of DifferentTagetesSpecies

Abstract

The diversity of thiophenes (natural biocides) and the differences between the concentrations of these compounds in the leaves and roots of Tagetes erecta L., T. patula L. cv. Nana furia, and T. minuta L. (marigolds) indicated the presence of at least two different sites of accumulation: leaves and roots. Leaf explants of Tagetes, however, are used by preference to obtain callus cultures. Once subcultured, secondary (C₂) calli of T. patula obtained from leaves of 4 to 7-week-old plants, contained higher amounts of accumulated thiophenes (up to 80% of the amounts in the leaves) than original (C₁) or twice subcultured calli (C₃). The concentrations of thiophenes in C₂ calli of T. minuta were about half those of C₁ calli, while the concentrations of thiophenes of C₁ calli amounted to 1-2% of the leaf values. Most of the C₃ calli of T. minuta did not contain thiophenes at all. Although C₁ calli of T. erecta also contained considerable amounts of thiophenes, the C₂ calli died, most likely owing to high levels of accumulated polyphenolic compounds. The combination of species effects and the physiological state of plants and calli provides adequate information to decide whether Tagetes calli are able to produce thiophenes or not. It is concluded that the ability to produce thiophenes does not depend on the organ used, but on the genetic information present in the species, and on the physiological state of plants and calli, particularly their age.