| Vetiveria zizannoides is one of ideal plant species used to soil conservation and environmental rehabilitation, with its adaptable, fast growth and reproduction, well-developed root system, drought and salt resistant properties and so on. In this study, the possible physiological and biochemical mechanisms of Vetiveria zizannoides tolerance to lead were investigated using water culture system. At the same time, the regeneration system of vetiver is constructed and the gene AtCBF3, which was cloned form Arabidopsis thaliana, was transformed to vetiver mediated by Agrobacterium.The main results are as follows:1. At low Pb concentration (i.e., less than 200 mg/L Pb), the growth rate and chlorophyll content of vetiver grass increased as compared with those of control. With the increase of Pb concentration, the growth state of plants is subjected to different degrees of inhibition. For example, leaf growth rate, plant tillering, root growth, chlorophyll synthesis was inhibited significantly.2. The activities of SOD, POD, CAT of leaves of plant treated by different levels of leadwere measured. The results show that vetiver has strong patience to Pb. By the concentration of Pb in root and shoot of plants measured , it shows that: vetiver plants have a stronger absorptive capacity of Pb. In addition, vetiver itself has a powerful biomass. So Vetiver grass is a good material of phytoremediation of Pb polluted environment.3. Vetiver has multi-application in different areas, but its own weak cold tolerance limits its application in the cold zone. Based on the establishment of tissue culture of vetiver, and with agrobacterium-mediated transformation technology, the transgenic plants were obtained.(1) The foundation of regeneration system The source of explants, light conditions, plant growth regulator combination are the main factors that affect plant callus induction and plant regeneration. In this study, first of all, choose the axillary bud as the explant,then through the optimization of medium components, obtained the best callus induction medium: MS + 3.0 mg / L 2,4-D + 0.5 mg / L KT. Different media conditions will produce different types of callus. Which are yellow-white and granular are embryogenic callus that have capable of regeneration; and which have no significant structure are non-embryogenic callus that can not regenerated. Added the appropriate amount of hydrolysis of casein protein to medium, it can significantly improve the quality of callus and increase the capacity of differentiation. The better medium for differentiation: MS + 0.5 mg / L NAA + 1.0 mg / L 6-BA, the better medium for rooting: 1 / 2 MS + 0.5 mg / L NAA. Callus induction frequency is about 78%,and the regeneration frequency of embryogenic callus is above 95%. The whole process from callus induction to green plantlets transplanted to soil needed about 5 months.(2) Agrobacterium-mediated genetic transformation At first, AtCBF3 was linked to vector pCAMBIA1301 to construct the plant expression vector pCAMBIA1301/AtCBF3. And the gene was transferred into the genome of vetiver grass through agrobacterium-mediated method.
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