| Maize(Zea mays L.)is an important food crop in China.During the long-term storage process of maize seeds,they often encountered different adverse conditions such as extreme high temperature and high humidity,which is called the aging of seeds.The aged seeds mainly manifested in the decline of seed vigor and deterioration of quality,and also affected the storage and utilization of germplasm resources.Priming proves to be one of the effective and pragmatic approaches to improve the seed vigor,also known as osmotic regulation.Research suggested that hydrogen sulfide(H2S)was the third kind of gas signal molecule after NO and CO,which plays an important role in the growth and development of plants.In this study,Zhengdan 958 maize seeds were exposed to controlled deterioration treatment(CDT)at 42℃ and 100% relative humidity for 5 days,mainly for simulating deterioration process of seeds under natural conditions.Then used a series of different concentrations of Na HS(H2S donor)to do the priming treatment.We discussed the effect of Na HS on the aging of seed vigor through a series of technology means,for instance,the standard germination experiment,the determination physiological index,isozyme activity staining and antioxidant experiment verification in vitro.The aim was to clarify the main mechanism and effect of Na HS as priming agent to repair the vigor of Maize seed.The main results are as follows:(1)With the increase of aging degree,the seeds lost their vigor gradually,accompanied with the cell membrane structure integrity destroyed.The most direct comprehensive performance is the seed germination rate decreased.The results revealed that different concentrations of Na HS priming could promote the seeds sprouting,enhance the internal physiological metabolism,and significantly improve the germination rate of aging maize seeds,with 100 μmol/L as the best concentration.(2)The results of physiological indexes showed that the active oxygen free radicals of maize seed embryos were accumulated excessively by aging stress,the membrane lipid peroxidation degree was obvious,and the activity of antioxidant enzyme decreased.Na HS priming treatment could remove the active oxygen species in the embryo effectively,reduce the lipid peroxidation degree of cell membrane,induce the content of hydrogen peroxide(H2O2),superoxide anion(O2·-),and malondialdehyde(MDA)declined,some antioxidative enzymes such as peroxidase(POD),catalase(CAT),superoxide dismutase(SOD)and non-enzyme antioxidants such as glutathione(GSH)enhanced under stress conditions,which had a positive effect on the repair of seed vigor.(3)Isozyme activity staining results indicated that after aging stress,the metabolic activity of maize seed embryos was weakened,the activity of catalase and peroxidase isoenzyme decreased compared with those of normal embryo,which showed that the bands of isozyme electrophoresis spectra were dark and low in expression.Na HS priming treatment reactivated the physiological metabolic process,with the expression of isozymes increased,and the stripe color became brighter.(4)In vitro antioxidant assays showed that Na HS can effectively scavenge reactive oxygen species such as hydrogen peroxide(H2O2)and superoxide anion radical(O2·-),which can better reflect the antioxidant properties of hydrogen sulfide gas signal molecules.(5)This study used TCA/acetone method to extract the normal,aging,Na HS priming seed embryos protein.After for preliminary analysis of proteomics by PDQuest software.The total of different protein spots was sixty-five,of which 14 spots existed more than twice times significant difference and abundance changes are more obvious.According to the trend of abundance change differentially expressed protein spots,the differentially expressed protein spots in this study can be divided into three types,the expression first increased and then decreased,the expression first declined and then rised,the expression was not obvious. |
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