The Establishment Of Genetic Transformation System In Sedum Alfredii Hance And Its Use In Clean-up Of The Multiple Metals-polluted Water

Sedum alfredii Hance is a kind of shade plant and has the characteristics of rapid growth, large biomass and easy reproduction. S. alfredii is able to accumulate a large number of Zinc (Zn) and Cadmium (Cd) from the soil. However, the sensitivity of S. alfredii in unsuitable environments such as high temperature, saline and drought stress has confined its application range. Reactive oxygen species (ROS) will lead to the oxidative damage in plant. The superoxide dismutases (SOD) plays an important role in eliminating ROS and thus confers to the improvement of stress resistance in SOD transgenic plants. In the present study, sod gene that cloned from a drought resistant cyanobacterium Nostoc flagelliforme was transferred into Sedum alfredii Hance with the help of agrobacterium LBA4404. The callus grew faster in medium containing2.0mg L"16-BA and0.3mg L-1NAA compared to other conditions. The bud induction needed a long time. In the phase of shoot elongation, the combined treatment of2.0mgL-1GA3and0.1mgL-16-BA could result in stronger shoots. In addition, the reduction of agarose hardness was found to be advantageous for root induction. The PCR analysis had confirmed that sod gene from N. flagelliforme was integrated into the genome of S. alfredii. Meanwhile, it had been expressed in the leaves. We have successfully established the genetic transformation system of S. alfredii. The transgenic callus and plants showed more resistance to osmotic stress (e.g.400mmol/L and600mmol/L mannitol) compared to wild-type plant in our preliminary research. Under the conditon of high temperature, wild-type callus was more severe browning than the transgenic callus, and it indicated that exogenous sod gene could improve S. alfredii tolerance to high temperature.S. alfredii can grow well under aquatic condition and accumulate a large amount of Zn and Cd. The clean-up of S. alfredii on multiple metals-polluted water was also evaluated in this research. We added different concentrations of compound heavy metals into1/8MS (pH7.0) to simulate the natural waters. It is found that Cd and Zn promoted the relative growth of plant fresh weight, the photochemical efficiency of leaves and chlorophyll-a. Cd, Pb and Zn showed a synergistic action in compound pollution with0.01mg/L,0.10mg/L and0.20mg/L.