Effects Of 5-aminolevulinic Acid (5-ALA) On Physiological And Biochemical Indexes And Genomic DNA Methylation Of Maize Seedlings Under NaCl Stress

Maize is the main food source of human and animals in the world,and it is also an important food crop and industrial raw material crop in the country.It has an important economic and social status in China.The soil salinization seriously restricted the improvement of maize yield and the development of planting conditions.The research on improving the salinization resistance of maize has important practical significance and research significance.In recent years,the use of 5-aminolevulinic acid(5-ala)to improve the salinity resistance of different plants has been increasing.This study with maize inbred lines B73 as materials,and 5-aminolevulinic acid(5-ala)of different concentrations was used in seed soaking treatment,and then cultured under the stress of sodium chloride until the trifoliate stage.After that determination the change of the physiological and biochemical indexes,and uses the methylation sensitive amplification polymorphism(MSAP)technology to analysis the changes of the DNA methylation pattern and level under the NaCl stress.The results show that:1.Under the stress of salt conditions,different concentration of 5-ALA seed handling for maize have influence for the activity of antioxidant enzymes(superoxide,peroxidase,catalase),when the concentration of 5-ALA in 0.05 mg/L ~ 0.5 mg/L the range of the activity of antioxidant enzyme was increase first and then decrease,When the concentration of 5-ala was between 0.1 mg/L to 0.5 mg/L,the activity of antioxidant enzymes in maize was the highest.2.Evaluate the soluble sugar and soluble protein content in the experimental group can be found that after the 5-ALA concentration is 0.05 mg/L ~ 0.5 mg/L range,soluble sugar and soluble protein content in maize has the same change trend,the trend is increase first and then decrease,when the concentration of 5-ALA is 0.1 mg/L the content of the soluble sugar and soluble protein were maximum.3.Methylation analysis showed that when the concentration of 5-ala was between 0.05 mg /L to 0.5mg /L,the total methylation rate first decreased and then increased,the whole methylation rate decreased,and the semi-methylation rate first increased and then decreased.In addition,the total methylation rate,semi-methylation rate and whole methylation rate of each experimental group were all lower than those of the control group.The semi-methylation rate of each experimental group was higher than that of the whole methylation rate.4.Methylation analysis showed that,with the increase of 5-ala concentration,the methylation-sensitive amplification polymorphism of each experimental group first decreased and then increased,and the monophyletism first increased and then decreased.The methylation patterns of each experimental group changed to different degrees.With the increase of 5-ala concentration,the percentage of difference sites between type A and type D was type A: 29.06%,31.04% and 28.23%.Type B: 30.61%,30.07%,33.38%;Type C: 35.40%,35.04%,33.85%;Type D: 4.93%,3.86%,4.54%.Among them,the values of type A,type B and type C are similar,and the values of type D bands are the smallest with A large difference.