Study On Cd Accumulation Mechanism And Selection Of Cultivars With Low Cd Accumulation In Cucumber

Cucumber（Cucumis sativus L.）is one of the main vegetable crops in China,the planting area of the largest and most productive,however,with the development of heavy industry in recent years,China’s farmland and facilities in the soil heavy metal cadmium pollution is a trend of dramatic increase,effect on cucumber yield and quality are also increasing.Studies showed that when the soil was moderately polluted with cadmium,the cadmium exceeding rate of common cucumber fruits was 25%,while that of fruit cucumber fruits was as high as 71.4%^[1].However,there are few studies on the mechanism and mechanism of cadmium accumulation in cucumber fruits.Therefore,it is of great practical significance to explore the related genes and regulatory mechanism of cadmium absorption and accumulation in cucumber.Therefore,the main transporters of cadmium absorption and aboveground tissue transport in cucumber were identified by the methods of multiple omics,biochemistry and molecular biology,which laid an important genetic resource for breeding cucumber varieties with high resistance and low accumulation.The main experimental results are as follows:1.The Nramp,HMA and ZIP protein families responding to cadmium stress were screened by RNA-seq using R1461 inbred line as material.2.Subcellular localization results showed that both CsNramp1 and CsNramp4 were localized to the plasma membrane.3.The results showed that the expression levels of CsHMA2 and CsNramp4 were positively correlated with the content of cadmium in the overground part and root of cucumber respectively,and 13 high-accumulation varieties and 10 low-accumulation varieties were selected.4.Cd content was detected by ICP-MS,and the expressions of CsNramp1,CsNramp4,CsHMA1 and CsHMA2,CsZIP1 and CsZIP8 in 23 different cucumber cultivars were detected by q-PCR.The results of correlation analysis showed that expression CsHMA2 and CsNramp4 expression were positively correlated with cadmium level inaboveground and underground parts,respectively.5.Grafting experiments were carried out on Jinyou 12,Jinmei 3,Jinyou 49 and R1461 inbred-lines.The results showed that CsNramp4 was involved in the absorption of cadmium ions in roots,while Cs HMA2 is responsible for the transport of cadmium from root to shoot.