The Studies On Expressing PvSR2 Gene Using Attenuated Virus Vector Toreduce Cadmium Contentin Tobacco Plants

In recent years, the heavy metal pollution has become a serious problem; the soil cadmium(Cd) pollution was one of the important factors that affect the food safety in our country. Controlling heavy metal content in plant during crop growing is an important step to prevent from heavy metal pollution in agricultural food. In this paper, the current situation of heavy metal pollution of agricultural products and the technology to control the heavy metal pollution are described. Aiming at the difficult problem of controlling the heavy metal pollution of agricultural foods, it was studies that usingrecombinant virus vector p CB-CMVF209no2b-Pv SR2 reduces the heavy metal cadmium content of tobacco plants.1.Construction of recombinant cucumber mosaic virus(CMV) vector p CB-CMVF209-Pv SR2 containing Pv SR2 gene. In this experiment, we constructed a recombinant vector p CB-CMVF209no2b-Pv SR2 with Pv SR2 gene by double enzyme digestion method, which was based on the vector of cucumber mosaic virus vector p CB-CMVF209-no2 b. After PCR identification and sequencing identification, it was confirmed that the Pv SR2 gene vector was successfully constructed.2.Effect of Pv SR2 gene expression on the content of heavy metal cadmium in tobacco plants. Five treatments(Pv SR2 treatment, empty vector treatment, Mock treatment, Bar1 treatment and Bar2 treatment) were designed in the experiments. Using Agro-infiltration method, Two pieces of leaf from Nicotiana benthamiana seedlings were inoculated with the recombinant attenuated virus vector p CB-CMVF209no2b-Pv SR2, p CB-CMVF109 and p CB-CMVF309, 10 days later, the soil of the tobacco planted was treated with cadmium(Cd2+ concentration: 2.5mg/kg soil), 15 days later, the collected tobacco leaf samples were tested by the coupled plasma emission spectrometer for the detection of cadmium content. Tested results showed that the cadmium content of plants with Pv SR2 treatment was extremely significantly lower than that of other treatment, Pv SR2 treatment was 4.42% of cadmium content in Mock treatment group.its average value was 0.6433mg/kg;empty vector treatment was 12.2367mg/kg;Mock treatment was 14.5667mg/kg; Bar1 treatment was 11.8667 mg/kg and Bar2 treatment was 11.4233 mg/kg.3.Gene Expression and detection of recombinant CMV virus in tobacco. The total RNA of leaf samples were extracted for 10 days after inoculating tobacco plant by Agro-infiltration, and then RT-PCR was conducted. The results showed that the Gene from the recombinant virus was successfully expressed in treated tobacco plant respectively, including the Pv SR2 gene.The comprehensive analysis showed that the expression of Pv SR2 gene in tobacco plants extremely significantly reduced the content of heavy metal cadmium in tobacco plants, and enhanced the plant resistance to heavy metal cadmium.