Cloning And Expression Analysis Of γ-ECS And HGSHS Genes In Soybean Under The Stresses Of Phosphorus Deficiency And Aluminium Toxicity

GSH is an important Tri-peptide compounds of small molecule in organisms, which have a high level of expression in microbe、plant and mammal. GSH play an vital role in resisting the process of various stresses (eg drought, cold damage, and heavy metals), There are homoglutathione in some plants and especially legumes.And the most frequently observed is homoglutathione(hGSH) that its function is similar to glutathione.It is produced through the operation of two successive enzymes:γ-glutamyl glycine synthase and hGSH synthase. And in the presence of ATP, hGSH produced by glutamic acid, cysteine, and alanine synthesis. A large number of studies have indicated that,(h)GSH synthesis and its synthetic metabolism related enzymes activity enhancement, can enhance plant resistance to adversity. Therefore, in plants γ-ECS and GSHS play significant roles in resistance responses. In this experiment, double-resistant soybean BX10as the experimental materials to study the activity changes of γ-ECS and GSHS under the stress of Phosphorus Deficiency (-P) and aluminum toxicity (+Al), and analyze the gene expression of these two enzymes in molecular level, in order to research their functions, that will be good at improving the resistant soybean varieties and further study in molecule. The results showed that:(1) The activity of y-ECS has increased under-P and+Al treatment in roots and leaves. Compared with-P treatment condition and their normal control, the activity of γ-ECS increased maximum23%in root, and36%in leaves; Compared with+Al treatment condition and their normal control, the results are33.8%in root and32.3%in leaf. In addition, in the different periods, the root’s y-ECS activity in+Al treatment is always greater than it in-P treatment. And the leaves’y-ECS activity in+Al treatment condition is significantly lower than it in-P treatment, when the roots were disposed after12d.(2) In head stage of processing, GSHS activity had no significant changes both in roots and leaves. With the treatment time become longer, activity of GSHS in roots and leaves up to a varying point, in-P treatment, the maximum amplitude of GSHS content in BX10was respectively76%in leaves and40.3%in roots; in+Al treatment, the maximum amplitude of GSHS content in BX10was respectively42.8%in leaves and88%in roots; both of them appeared at the end stages of processing.(3) Semi-quantitative RT-PCR analysis showed that:y-ECS gene expression quantity was strong under P deficiency and Al toxicity, but along with the treatment time, about12d treatment, y-ECS gene expression in leaves returned to control level. With the-P treatment time (12d), y-ECS gene expression both in leaves and roots returned to control level or even below. GSHS gene expression quantity was strong under P deficiency and Al toxicity, especially at the end of processing (12d), the expression rise highly in roots. However, with-P treatment2d, the relative expression of GSHS in leaves reached the maximum. Then, it decreased.In conclusion, the results in this study proved that BX10soybean could be in response to the P deficiency and Al toxicity and keep the metabolic balance by up-regulating the expression of GSH gene, increased the activity of GSH synthase and GSH/GSSG ratio. It meant soybean glutathione metabolism has efficiency in response to P deficiency and Al toxicity, which will provide the necessary theoretical basis for improving new soybean breeds.