Influence Of Exogenous ABA On Some Physiological Index And Whole Genome DNA Methylation Of Zea Mays Leaves

Previous studies found that exogenous ABA can enhance stress resistance of plants such as maize,wheat and rice,etc.and increase the activity of antioxidant enzymes(AOEs)such as SOD,POD and CAT,etc.At present,there are many researches on treating maize seedlings with exogenous ABA and studying their physiological and biochemical changes.But most of the researches imposed environment stress such as cold stress and osmotic stress,etc.In order to further understand the influence of the action mechanism for enhancing plants’ stress resistance of exogenous ABA on maize seedling leaf genomic methylation,this paper determined parts of physiology indexes of the maize seedlings and studied the maize seedling leaf genomic methylation by using the technique of methylation-sensitive amplified polymorphism(MSAP).And the results mainly turned out as follows:1.This paper studied the influences of spraying ABA of different concentration on superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),malondialdehyde(MDA),electrical conductivity(EC)and free proline(Fpro)of the maize seedling leaves.The results show that after spraying exogenous ABA of 15,20,and 25μmol/L,the maize seedling leaf SOD,POD and CAT activity increased significantly;the MDA content decreased to a certain degree;EC decreased to some extent;but Fpro did not change noticeably.In the third-fifth day after ABA treatment,SOD,POD and CAT activity were all the highest while the MDA content was also the lowest,which indicates that the inoxidizability of maize seedlings increased.2.This paper studied the maize seedling leaf whole genomic methylation by using the technique of MSAP.The results indicate that the maize seedling leaf genomic methylation rate was 20.46%after normal treatment.However,it increased to 21.37%after treated with exogenous ABA of 5μmol/L,to 21.79%with 15μmol/L and to 22.10%with 25μmol/L.The above results show that the maize seedling leaf genomic methylation rate increased to some degree after treated with exogenous ABA.In conclusion,spraying exogenous ABA increased the activity of AOEs(SOD,POD and CAT)of the maize seedling leaves,decreased the accumulation of MDA and reduced the electric conductivity of the leaves.This paper further determined the whole genomic DNA methylation and found that DNA methylation increased to some degree after ABA treatment.This result suggested that the maize seedlings had regulated at the genetic level after treated by ABA of different concentration.The experiment results show that ABA treatment can enhance stress tolerance of the plant and such stress tolerance may be related to the changes of its genome methylation.Consequently,this experiment can provide theoretical basis for future studies on application of ABA in stress-resistance cultivation of maize and other crops.