Transformed Roots of Lupinus mutabilis: Induction, Culture and Isoflavone Biosynthesis

Abstract

Transformed roots of Lupinus mutabilis cv. Potosi induced by Agrobacterium rhizogenes strain R1601 were cultured on Murashige and Skoog-based medium lacking kanamycin sulphate, or with this antibiotic at 40 mg l⁻¹. The neomycin phosphotransferase gene in the genome of transformed roots was confirmed by non-radioactive Southern hybridisation. Neomycin phosphotransferase protein was detected by ELISA. Transformed roots synthesised isoflavones, but not quinolizidine alkaloids; the latter are typical secondary metabolites of lupin normally produced in aerial parts of the plant. Genistein and 2′-hydroxygenistein, were the main secondary metabolites in cultured, transformed roots, whereas the glycoside genistin was more abundant in roots of non-transformed plants. Wighteone concentrations in transgenic roots were higher than those of non-transformed roots. Transformed roots produced twice the concentration of isoflavones compared with roots from non-transformed plants, indicating that Ri plasmid T-DNA genes modified isoflavone concentration and pattern of biosynthesis.