Preliminary Studies On Differentially Expressed Proteins Related To Nicotine Biosynthesis In Flue-cured Tobacco Roots

Nicotine content ,which was affected most by topping among all the cultivatio-n measures,is an important index to assess the quality of tobacco. For a long time,Tobacco research workers have done many research works to resolve the issue of high nicotine content in upper leaves from the point of view of cultivation, soil and fertilizer science,but the problem does not fundamentally solved yet. As nicotine is an important secondary product in tobacco, the synthesis and accumulation process is a very complex network control. Thus the regulation of the nicotine synthesis and accumulation of protein dynamics were researched by proteomics method before and after topping, and this paper reveals the molecular basis on nicotine content by topping with great potential.The main results are as follows.1. Though the topping and simulating Jasmine acid treatment,we obtuin and extract tip-top protein for 2DE/MS.Then we obtion four meaningful different proteins((spermine / spermidine synthase, S dehydrogenase, glyceraldehyde 3 - phosphate dehydrogenase).2. On this basis ,two cata;ysate(S, spermine / spermidine)were used to treat the tobacco to verify the relationship between the nicotine synthesis and them .The result showed that,compared to topping,in the root tip tissues treated with S after topping,the expression of sut1,PMT,and glyceraldehyde 3 - phosphate dehydrogenase gene declined,SPS,GS,NR activity declined,and sucrose content also declined; compared to no topping,in the root tip tisses treated with spermine/spermidine,the expression of sut1and glyceraldehyde 3 - phosphate dehydrogenase gene declined,whereas the expression of PMT gene increased,SPS,GS,NR activity increased,sucrose contentincreased,and the content of nicotine biosynthesis increased.These resultes showed that the S plays a negative role and spermine / spermidine plays a positive regulation role in the nicotine biosynthesis.