Effect of cadmium, alone or in combination with CaCl2, on the growth, antioxidative enzyme activity and cadmium absorption of Solanum nigrum L. var pauciflorum hairy roots / 生物工程学报

To study if Solanum nigrum hairy roots can be used for phytoremediation of Cd contamination, we investigated the effects of cadmium (Cd) alone, and in combination with different concentrations of CaCl2, on growth, activities of superoxide dismutase (SOD) and peroxidase (POD) and Cd absorption by hairy roots of S. nigrum L. var pauciflorum. The results showed that Cd concentrations of lower than 50 micromol/L enhanced the growth of hairy roots, while higher than 100 micromol/L inhibited growth and decreased the number of branched roots, also causing the root tips to become brown and shorter in length. In comparison with a control, the soluble protein content, the activities of SOD and POD in hairy roots cultures showed a trend of first increased and then gradually decreased, while the malondialdehyde (MDA) content significantly increased, when increasing the Cd concentrations. Cd concentration of 100 micromol/L or 300 micromol/L in combination with 10-30 mmol/L CaCl2 resulted in a decreased content of soluble protein and MDA in the hairy roots, but an enhanced SOD activity. The increased POD activities were observed when cultured in 100 micromol/L Cd and 10-30 mmol/L CaCl2 but decreased when cultured in 300 micromol/L Cd and 10-30 mmol/L CaCl2. Atomic Absorption Spectrometry determination showed that the Cd absorbed and adsorbed by the hairy roots increased along with the increase of Cd concentration. The exogenous addition of 10-30 mmol/L CaCl2 could reduce the toxicity of Cd. This was achieved on one hand by reducing the absorption of Cd, on the other hand by decreasing the lipid peroxidation through regulating the activities of antioxidant enzymes SOD and POD in the hairy roots.

Induction and in vitro culture of Wedelia trilobata hairy roots / 生物工程学报

To study the possibilities for improvement of the ornamental character and production of secondary metabolites by using Wedelia trilobata hairy roots, we investigated the induction of W. trilobata L. hairy roots and its consumption changes of carbon resource, nitrogen resource, phosphate and calcium in the medium during liquid culture. The results showed that hairy roots could be incited from the cut edges of leaf explants 7 days after inoculation with Agrobacterium rhizogenes ATCC15834 and could have an autonomous growth on the medium without phytohormones. The PCR amplification showed that rol genes of Ri plasmid of A. rhizogenes was integrated and expressed into the genome of transformed hairy roots. The hairy root line grew very slowly in 0-7 days, very fast from 7 to 21 days. During the liquid culture of hairy roots, sucrose, NO3(-)-N, PO4(3-) and Ca2+ in the medium could be gradually absorbed and utilized with time. The content of NO3(-)-N in the medium was 5.8% of the initial amount at day 7, while sucrose content was about 50% of the initial amount. At day 35, the NO3(-)-N and sucrose content in the medium was 1.82% and 3.39% of the initial amount, respectively. In combination with Ca2+ consumption, PO4(3-) of the medium was rapidly absorbed and utilized. At day 7, the content of PO4(3-) in the spent medium was only 1.76% of the initial amount; but even at day 35, the content of Ca2+ in the spent medium was still 61.3% of the initial amount. The results presented here had provided the possibilities on improvement the ornamental character and how to prepare optimum medium for large scale cultivation and production of secondary metabolites from W. trilobata L. hairy roots.