The Effects Of Chilling On Antioxidant Enzyme Systems And Difference Of Gene Expression Levels During Seed Germination And Seedling Of Sweet Corn

Research on Physiology and Biochemistry and gene expression mechanism during seeds germination under cold stress.It can not only provide theoretical and technical support for the identification and screening of low temperature germplasm resources, and cultivate high seed germination potential, but also provide reference for the defense of cold damage.In this experiment, seeds of a set of sweet corn lines were used on germination and seeding test under cold stress. On the basis of the result of germination test,two lines(tolerant line ‘1132' and sensitive line ‘GuoquT12') were screen out for study on change trends of MDA content and antioxidant enzyme(SOD, POD and CAT) activity and gene expression during seeds germination and seeding under10? and 26?:(1) In general, MDA content of tolerant line ‘1132' is stronger than sensitive line'GuoquT12',This may be the reason why ‘1132' is better ability to defense the cold than the ‘GuoquT12'when with cold treatment;(2) In germination and seedling, cold tolerance of sweet corn varieties‘1132'antioxidant enzyme activity is higher than the cold-sensitive varieties of sweet corn ‘GuoquT12'. It illustrates cold press is closely related to antioxidant enzyme activity in seed germination and seedling of sweet corn, but different sweet corn varieties have different tolerance in low temperatures;(3) In the germination stage, found SOD, POD, CAT activity of two inbred varieties have no consistent trend at low temperatures, but at the beginning, their activities are rise when experiencing low temperature, indicating that the three enzymes play protective roles; In the seedling stage, '1132' 's SOD, POD, CAT activity remains high activity at the initial low-temperature, then decreased. While the 'GuoquT12' is slowly rising, then low, but the activity of the entire time periodis less than the species '1132', which shows antioxidant enzyme system of the variety with resistance cold can respond quickly to resist chilling injury in the early stage, but 'GuoquT12' can not;(4) By real-time quantitative PCR analysis gene expression levels of antioxidant enzymes, found that in the germination and seedling stage, gene expression and activity had no strict consistency, only isozyme gene SOD9 and SOD3 had consistency in germination. Gene expression of SOD3, SOD9,CAT3 has same trend, indicating that gene expression is a complex process; And some isozymes gene expression is relatively low, such as, SOD4, POD1 and CAT2,SOD3, SOD9 of the germination period, POD3 and CAT2 of seeding stage,illustrated enzymes had the different types at different times.