GREENING OF NONTRANSFORMED AND AGROBACTERIUM-RHIZOGENES TRANSFORMED ADVENTITIOUS POTATO ROOTS

Light-induced chloroplast differentiation in potato (Solanum tuberosum L. cv. Istra) was studied in cultures of adventitious roots originall y induced in vitro on nodal plant segments, and of hairy roots transfo rmed with Agrobacterium rhizogenes, mannopine-type, strain 8196. Red f luorescence, due to chlorophyll accumulation, was first observed, in h airy roots after 2-3 days of light exposure and several days later in cultured normal roots. In both cases, the concentrations of chlorophyl l and carotenoids then increased gradually. As evidenced by electron m icrographs, the chloroplasts developed from leucoplasts via a sequence of leuco-chloroplasts, DAB (diaminobenzidine) positive thylakoids fir st appeared in leuco-chloroplasts indicating the beginning of photosyn thetic activity. The photosynthetic activity of green hairy roots was higher than that of green non-transformed roots. In non-transformed po tato roots, BA stimulated while IAA and GA(3) inhibited light-induced pigment accumulation.