Selection of penstemide and serrulatoloside producing clones in penstemon serrulatus by small-aggregate cloning.

A plating method is described for cultured cells of Penstemon serrulatus Menz. which allows effective cloning of aggregates consisting of less than 10 cells, on a simple synthetic medium. The obtained clones snowed high diversity with respect to their ability to produce penstemide, an ester iridoid of the Valeriana-type. Some of the clones produced higher quantities of this compound than the original cell line. The content of another iridoid glucoside of the same type, serrulatoloside, was also determined.