Study On Mechanism Of Inducing Drought Resistance In Maize By S-ABA

Maize(Zea mays)is considered to one of the three major cereal crops in the world,the total yield and planting area is only second to rice and wheat.Drought is an important topic that urgently needs to be addressed,particularly in the light of rising global temperatures.The consequences of drought stress in crop production systems are perhaps more deleterious than abiotic stress under changing climatic scenarios,which seriously restrict maize yield.The Huang-Huai-hai area is an important region for the planting of summer maize,and here the occurrence of drought stress during the growing period may hamper water use efficiency leading to significant yield losses.S-Abscisic acid is one of endogenous plant hormones with important physiological activities.Further deepening scientific research has found that S-ABA can induce the resistance in plants against harsh environments and its application is receiving more and more attention on agriculture.In this study,hydroponic cultivation method was used to study the effects of soaking seeds with S-ABA hormones on germination of maize seeds under germination stress and seedling growth.The greenhouse cultivation method was used to study the different concentrations of S-ABA under different drought stresses.Physiological and Biochemical effects of antisperm spray on maize seedlings and the optimum concentration of S-ABA and Its synthetic inhibitor sodium tungstate on physiological,biochemical and endogenous hormones of maize seedlings under drought stress;The effect of S-ABA on the expression of Asr1 in maize.The main test results are as follows:1)Results indicated that,under drought stress,S-ABA treatment significantly improved maize seed germination rate(GR),germination energy(GE),and seedling biomass.After spraying 4 mg/kg S-ABA onto leaves,the endogenous hormone ABA,osmotic substances,antioxidant enzyme activities,and expressive quantity of the Asr1 gene were extended and MDA content dropped significantly.Moreover,ZD 958 endogenous ABA content,osmotic substances content,antioxidant enzyme activity and Asr1 gene expressive quantity were higher than that of XD 20.In conclusion,S-ABA treatment increased the content of endogenous ABA,induced an increase in antioxidant enzyme activity and Asr1 gene expression level,reduced the oxidative damage caused by drought to maize leaves,and improved the adaptability of maize seedlings to withstand drought stress.The promoting effect of S-ABA on the drought-tolerant variety ZD 958 was more obvious.These results serve as a reference for the use of S-ABA in mitigating drought stress in maize.2)Results indicated that,under drought stress,S-ABA treatment significantly improved maize drought resistant ability.After spraying 25 mg/kg S-ABA onto leaves,the chlorophyll content,photosynthetic characteristics,endogenous hormone ABA,osmotic substances,antioxidant enzyme activities,and expressive quantity of the Asr1 gene were extended.Moreover,MDA content dropped significantly and ZD 958 ABA content,osmotic substances content,antioxidant enzyme activity and Asr1 gene expressive quantity were higher than that of XD 20.In conclusion,S-ABA treatment reduced chlorophyll degradation and increased photosynthesis,increased the content of endogenous ABA,induced an increase in antioxidant enzyme activity and Asr1 gene expressive level,reduced the oxidative damage caused by drought to maize leaves,and improved the adaptability of maize seedlings to withstand drought stress.The promoting effect of S-ABA on drought-tolerant variety ZD 958 was more obvious.Through principal component analysis,the comprehensive evaluation of XD 20-MD was obtained,from large to small,from T3,T2,T4,T1,T5,T6.The comprehensive evaluation of XD 20-SD was from T3,T2,T1,T4,T5,T6.The comprehensive evaluation of ZD 958-MD was from large to small,followed by T3,T2,T4,T6,T1,T5.The comprehensive evaluation of ZD 958-SD from large to small was T3,T2,T1,T5,T4,T6.The drought resistance of maize under T3 treatment was the strongest.These results serve as a reference for the use of S-ABA in mitigating drought stress in maize.3)The results of greenhouse soil culture showed that under severe drought stress,S-ABA increased the chlorophyll content of maize leaves and increased photosynthesis.S-ABA treatment increased endogenous ABA content in maize,decreased endogenous ZT,GA3,and IAA content,and increased the ratio of ABA/ZT,ABA/GA3,and ABA/IAA,but the ratios of different parts were different.According to the factor and the principal component scores can S-ABA resistance element processing corn drought resistance in different parts of the comprehensive evaluation,the S-ABA resistance element of dealing with the different parts of corn in comprehensive evaluation from big to small order leaf,root and stem.The sodium tungstate treatment results are opposite,which increases the degree of damage to the corn caused by drought.S-ABA and endogenous ABA synthesis inhibitor sodium tungstate have important regulatory effects on different parts of maize(roots,stems and leaves)under severe drought stress.The enhancement of drought resistance of maize under severe drought stress by S-ABA may be closely related to the signal transduction of four endogenous hormones.