Artificial Ageing Antioxidant System Of Soybean Seed Germination Process

Germplasm resources are the most fundamental and strategic resources for human survivaland social progress. At present, preservation of germplasm in genebank at low temperature is themost important ways. But with the extension of storage time, seed vigor will still decline even belost. Seed aging(deterioration) leads to reductions in seed quality, performance and establishment,and it is difficult to quantify the economic loss caused by this phenomenon. Therefore, carryingout studies on the mechanism of seed aging has crucial theoretical and practical significance onagricultural production and germplasm preserving. In this study, artificial aging seeds withdifferent germiantion percentage "zhonghuang13" was used as materials, through the testing ofactive oxygen content, antioxidant levels, antioxidant enzymes activity, isoenzymic zymogramand isoenzymic genes expression, the effect of artificial aging on antioxidant system of soybeanwas analysed. The main results were summarized as follows:1. The activity of GR、MDHAR in embryonic axis of soybean was declined by aging. In theearly stage of aging DHAR activity did not change significantly, and had a small drop in lateaging. The activity of SOD was less affected by aging. During seed germination, the activity ofGR was increased, but the seeds of aging activity level is still less than CK seeds.2. The brightness of isozymes bands in GR became weak in aging seeds while deepen duringthe germination period. There was a new band of DHAR isozymes was detected in aging seedswhile the isoenzymes bands of SOD and APX changed slightly, but the brightness of MnSODbands became shallower.3. The results indicated that GR、MDHAR、DHAR、pAPX and MnSOD isoenzymes genesshowed reduced expression during aging, while APX1、APX2、FeSOD and CuZn-SODisoenzymes genes showed increased expression, and this might be the base of GR、MDHAR andDHAR activity decrease and isoenzyme band change.4. Antioxidant capacity of AsA in aged seeds was lower that of CK seeds. And the agingtreatment destroyed the stability of redox state of ascorbic acid in the seed, which affected thecapacity of the redox for sustaining the stability in the seeds. Aging reduced the total amount ofGSH+GSSG and the content of GSH in the seeds. In imbibition germination stage, the content ofGSH+GSSG and GSH in the seeds increased primarily and then decreased, while the ranges ofvariation of both in aged were less than that in CK seeds, with significant decrease of the contentof GSSG, and firstly increase and then decrease of the ratio of GSH/GSSG. However, the totalamount of the GSH+GSSG, the content of GSH and GSSG all decreased significantly, while theranges of variation of the ratio of GSG/GSSG was not evident in seeds with0germinationpercentage. The content of GSH, the total amount of GSH+GSSG and the GSH/GSSG in the aged seeds were all less than that in CK seeds, which showed that aging had reduced theantioxidant capacity in the seeds.5. The change of seeds antioxidant system had a close relationship with seeds vitality. Thedecrease of seeds antioxidant ability made the body can not effectively inhibit the accumulationof ROS caused by aging, and enhance the oxidative damage. The raise of O2–production rate andH2O2content in the early stage of aging verified the accumulation of ROS. And the ROS that cannot be removed timely enhanced the damage of cell and formed a bad cycle, and this situationcaused the seed fail to germinate and lose vitality.