Hairy root cultures of Digitalis lanata. Secondary metabolism and plant regeneration

Summary Pieces of leaves of axenically grown shoots and plants of Digitalis lanata were infected with different wild-type strains of Agrobacterium rhizogenes . Hairy roots were formed with only 3 strains, all wide host range agropine-type agrobacteria. Transformation was proven by detection of opines and by DNA hybridization with the probe pLJ 85. Plants were regenerated from the hairy roots either via somatic embryos or shoots. The content of secondary products of hairy roots and transgenic plants was examined by TLC, HPLC and the Na + /K + -ATPase assay for cardenolides. No cardenolides were detected in hairy roots and untransformed roots grown in vitro . However, anthraquinones and flavonoids were shown to occur. The content of these compounds was higher in hairy roots than in untransformed roots. Shoots and plants regenerated from hairy roots showed similar contents and spectra of cardenolides as untransformed shoots and plants. Roots of untransformed and transformed plants contained cardenolides that probably were formed in the shoots and transported into the roots.