Functional Analysis And Expression Profiling Of Silicon Transporter Related Genes CSiT-1and CSiT-2in Cucumber

Cucumber (Cucumis sativus L.) belongs to the cucurbitaceous plant, which is cultivatedthroughout the world, plays an important role in vegetable production and market supply. Cucumber isfond of warm environment, and can not tolerate a cold one; it likes hygrophilous condition instead ofwaterlogging; it needs fertilizers, but do not endure too much fertilizers. Because of its growth habits,cucumber is cultivated in a suitable condition which is limited by various factors.Silicon (Si) is a part of plant constitutes. It is considered to be a ‘‘quasi-essential” element forplant growth and beneficial for the growth of many plants,which particularly grows under variousabiotic (e.g.drought, salt and heavy metal toxicity) and biotic stresses (e.g. plant diseases and pests).The research is limited to the analysis of the expression level of silicon transporters in gramineas,however the role of silicon the mechanism of silicon transport and accumulation in plant are still notclear.Among dicots, cucumber has a high content of silicon. This study, using cucumber as theexperimental material, isolated silicon transport related genes CSiT-1and CSiT-2from cucumberthrough RT-PCR method, constructed eukaryotic expression vector and prokaryotic expression vector.We used a tumefaciens-mediated leaf disk transformation to obtain transgenic tobacco plants.Theexperiment studied the circadian expression profile of silicon transporter related genes CSiT-1andCSiT-2. Then we discussed the expression of silicon transfporter related genes CSiT-1and CSiT-2ofcucumber under the different concentrations of exogenous silicon (Na2SiO3·9H2O) through ahvdroponic study.The main conclusions were as follows:（1）Recombining CSiT-1, CSiT-2gene and the pBI121plasmid (contains35S promoter) severally,then expression vectors were constructed respectively. According to CSiT-1gene, we designed a pairof specific primers, constructed prokaryotic expression vector pET-30-CSiT, and expressed the vectorin E.coli BL21.It expressed the fusion protein by IPTG induction. After SDS-PAGE electrophoresisanalysis detection, we got specific bands with expectations.（2）CSiT-1and CSiT-2were expressed respectively in different tissues of cucumber, and everyoneof these expressions was different with each other. After processing by three kinds of concentration, the expression of CSiT-1and CSiT-2had obviously differentce compared with the untreatedexpression. At the same time, the expression of CSiT-1and CSiT-2was in circadian rhythm.（3） CSiT-1and CSiT-2were intorduced into tobacco by A.tumefaciens-mediated leaf disktransformation to obtain transgenic plants of CSiT-1and CSiT-2, then screened， analyzed the T1generation which was further verified by RT-PCR.（4）After processing transgenic tobacco (CSiT-2)and wild type tobacco by a kind of concentrationof silicon (0.02mM), we detected the content of silicon, and proved that silicon transport related tothe expression of gene CSiT-2.