The Expression Of GmABA8’OH Gene And The Analysis Of Salt Tolerance In Soybean

Abscisic acid (ABA) makes an important effect on normal growth and development aswell as in adaptive responses to environmental stresses in higher plants, such as drought,high salt and low temperature. ABA may induce adversity-responsive gene expression;accommodate the biological change and the metabolism of plant. As a result, ABA canavoid or reduce the harm to cells and tissues of the plant from stress of high salt. Forcorrecting and accurate actions, physiologically active ABA level is controlled throughfine-tuning of denovo biosynthesis and catabolism.8′-hydroxylation pathway is thepredominant ABA catabolic pathway in higher plants, which is catalyzed by8′-hydroxylase. In this paper, we constructed the ABA8′-hydroxylase gene silencing vector,and transformed it into soybean, tried to silence the ABA8′-hydroxylase gene in thegenetically modified soybeans, and to block the abscisic acid oxidation degradationpathway. As a result, it could make the abscisic acid accumulation in soybean cells ortissues, and increased the salt tolerance.In this experiment, we have employed gene-silencing technique to construct the genesilencing vector pBI-ABA, which contained the genetic fragment of8′-hydroxylase, thentransformed it into Jilin35using Agrobacterium-mediated method. Total80regeneratedplants and15PCR-positive transgenic plants were obtained. Quantitative expressionanalysis of gmABA8′OH gene in five T2generation of transgenic positive plants usingReal-time PCR showed that, the expression levels of gmABA8′OH in all detected plantswere lower than those of control plants,15%-55%respectively.The salt stress experiment was designed with three lines of T2generation of transgenicpositive and the control plants. which were growth under different gradients of saltcondition, such as0mM,60mM，120mM,180mM,240mM. Under low salt concentration(60mM), the growth of the transgenic plants and control plants were not significantlyaffected. With the increasing of salt concentration, the growth of the two groups wasaffected varying degrees of inhibition. Especially under the concentration of240mM salt,phenomenon of leaf wilted can be observed on non-transgenic soybean. In contrastalthough growth retardation happened on transgenic soybean, no wilted leaves occurred.When the time has come to8days, related physiological experiment were performed onone of transgenic materials. In comparison with wild type soybean, transgenic plant wasmuch better in terms of the proline, soluble sugar content and membrane permeability.When treated with180mM and240mM, proline and soluble sugar amount in transgenicplants leaves have increased nearly1.5and1.8times respectively than that of wild typegroup. Relevant data indicated that the gene of gmABA8’OH can be functional in endogenous salt resistance pathway of soybean, also salt tolerance of soybean can beincreased by interrupting expression of this gene.This study may provide some basis for culturing new salt-resistant varieties of soybeanby transgenetic technique.