In-vitro cloning of Dittrichia viscosa for screening nutritional ecotypes

Difficulties were encountered for in-vivo propagation of plants used for screening populations during evolutionary studies of Dittrichia viscosa W. Greuter, an invading ruderal species of the Asteraceae. Conditions suitable for in-vitro propagation of D. viscosa were first investigated. Plants were in-vitro cloned from nodal segments, and the best medium for mass production was a modified Murashige and Skoog medium. Up to 5 nodal microsegments could be produced per segment, and by repeated passages over 4 months, more than 10,000 microsegments were obtained. The segments were rooted in auxin-free medium and the plantlets, resembling juvenile plants, were grown in sand culture. Ecotypes from two contrasting mineral habitats and differing in their ability to select major cations (K, Ca and Mg), i.e. nutritional ecotypes, were cloned in vitro and in vivo and compared in common hydroponic conditions. Differences observed in cation accumulation were similar, irrespective of whether plants were derived from in-vitro or in-vivo clones. In-vitro culture did not alter the nutritional responses as observed with in-vivo mature plants.