Microsampling: an alternative approach using sesquiterpene lactones for systematics

The localization of sesquiterpene lactones in glandular trichomes of numerous Asteraceae makes it possible to use a microtechnique to investigate their occurrence. General aspects of the utility and value of the method in comparison with standard procedures are discussed with special focus on the advantage of a quick, inexpensive and reproducible analytical technique in systematic and biochemical studies. Using analytical HPLC, it was possible to establish the sesquiterpene lactone profiles of all 64 known taxa of the genus Helianthus. Intraspecific variation of sesquiterpene lactones was found to be low in comparison to morphological characters. Hybrids were shown to possess the additive sesquiterpene lactone patterns of their parents. This suggests that the chemistry of these compounds could be a useful tool in taxonomy.