Differences In Tolerance,absorption,accumulation And Translocation Of Cadmium In Four Cultivars Of Sweet Sorghum

China’s annual arable land abandoned by cadmium pollution has 1.4 million square hectares.Cadmium,one of the most toxic heavy metals,not only pollute the environment,but also enter the human body through the food chain.Therefore,the bioremediation of cadmium-contaminated soil is of great significance.Sweet sorghum,also known as sugar sorghum,sweet stalk and so on,is a variant of sorghum.It originates from drought,hot,soil-poor Africa continent,belongs to carbon four plants with low carbon dioxide compensation and high saturation.It is a widely cultivated crop variety which has the high photosynthetic efficiency in the world.It is one of the crops with the highest solar energy conversion efficiency and water conversion efficiency.It is an ideal bioenergy for drought-resistant,salt-tolerant,salt-tolerant,and biomass-rich crops.The use of sweet sorghum for bioremediation in cadmium-contaminated areas not only mitigates the energy crisis,but also transfers cadmium from the soil to the plant,avoiding harm to the human body.Therefore,screening sweet sorghum lines with strong tolerance and high translocation capacity has practical significance.In this study,four genotypes of sweet sorghum,KFJT-CK,KFJT-1,KFJT-3 and KFJT-4,were used research materials.Membership Function value of cadmium(MFVC)was applied.It was concluded that the resistance of four cultivars of sweet sorghum to cadmium was from large to small.: KFJT-3(0.473)> KFJT-1(0.458)> KFJT-CK(0.456)> KFJT-4(0.413).With the increase of cadmium concentration,the germination rate,germination potential,embryo length and radicle length decreased.When the cadmium reached 50mg/kg,the indicators decreased a significant level.Cadmium causes leaves chlorosis which gradually decreases from low internodes to high by morphological traits.KFJT-3 has the greater biomass compared to other cultivars and leaf conductivity,soluble protein and proline were increased by 2.06%,32.0% and 30.7%,respectively,under 50 mg/kg cadmium treatment.The stomata density decreased by 23.6% which showed strong adaptability in KFJT-3.The cadmium the highest in the root is,the stem and leaf are lower,and the cadmium content decreases from the low internode to the high internode in four cultivars of sweet sorghum.The cadmium of Bioaccumulation factor were KFJT-CK(1.67),KFJT-1(1.33),KFJT-3(2.92)and KFJT-4(2.54)and the translocation factor were KFJT-CK(0.32),KFJT-1,(0.49)KFJT-3(1.01)and KFJT-4(0.57).The expression of genes related to cadmium uptake,accumulation and translocatin was verified in four genotypes of sweet sorghum by RT-PCR.The expression of Sb Nramp3,Sb Nramp1 and Sbzip6 were 1.31,9.45 and 0.23 folds In KFJT-CK,respectively.The expression of Sb Nramp3,Sb Nramp1 and Sbzip6 were 2.56,10.70 and 0.33 folds in KFJT-1.the expression levels of Sb Nramp3,Sb Nramp1 and Sbzip6 were 3.29,1.36 and 0.63 folds,respectively,under the treatment in KFJT-3.In the treatment of KFJT-4,the expression levels of Sb Nramp3,Sb Nramp1 and Sbzip6 decreased by 0.29,0.59 and 0.57 folds.Finally,it is determined by physiological level,cell and molecular level that KFJT-3 is a strong cadmium tolerant,high translocation capacity cultivars,which laid a theoretical foundation for phytoremediation in cadmium contaminated soil.