For a number of these stages, from pre-meiosis up to the pollen tube, marker genes have been isolated that allow the study of the regulation of gene expression and development and their function in reproduction. Pollen has unique features to act as a model system, since it offers the opportunity to study, in haploid cells, cell fate, origin of polarity, cell division and signalling. Differentiation can be studied on developmental stages ranging from single cell up to a maximum of three cells. In addition to morphological development plants undergo also metabolic development, characterized by a fine tuning between primary and secondary metabolism. Secondary metabolites play an essential role in plant development, in sexual reproduction and in the interaction of the plants with their environment.
Many secondary metabolites are of great social importance as medicine, chemicals and drugs.
These aspects are studied with cell suspensions of Rubia and Morinda . These cells produce anthraquinones in a pathway that starts with the conversion of chorismate in isochorismate by the key-enzyme isochorismate synthase. The aim of the studies is to use the gene for isochorismate synthase as a molecular marker in the above mentioned aspects.