CQ10-LPSp对紫花苜蓿幼苗抗氧化酶和防御酶的作用

Effects of CQ10-LPSp on antioxidative enzymes and defense enzymes of alfalfa seedlings

为明确成团泛菌CQ10脂多糖(Pantoea agglomerans CQ10 Lipopolysaccharide,CQ10-LPSp)对紫花苜蓿(Medicago sativa)幼苗抗氧化酶和防御酶的作用,以紫花苜蓿‘巨能551’种子(种子表面消毒组和未消毒组)为试验材料,采用低浓度(0、0.067和0.134 EU·mL^(-1))和高浓度(0.200和0.267 EU·mL^(-1))的CQ10-LPSp与紫花苜蓿互作,研究CQ10-LPSp对紫花苜蓿幼苗的抗氧化特性[超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和丙二醛(MDA)]和防御酶活性[苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)和脂氧合酶(LOX)]的影响。结果表明:随着CQ10-LPSp浓度的升高,未消毒组和消毒组苜蓿幼苗的SOD、POD和PPO、PAL活性均呈先升后降趋势,在0.200 EU·mL^(-1)时达到最大值;MDA含量随着CQ10-LPSp浓度的升高呈先降后升再降的趋势,且均显著低于对照,而CAT活性却持续下降。低浓度CQ10-LPSp处理下,未消毒组幼苗CAT、MDA,PAL和LOX活性都大于消毒组,而POD、SOD和PPO却低于消毒组;高浓度CQ10-LPSp处理下,未消毒组幼苗CAT和MDA小于消毒组,POD、SOD和PAL高于消毒组。综上所述,紫花苜蓿幼苗对CQ10-LPSp的耐受能力存在浓度阈值效应,其耐受能力随着CQ10-LPSp浓度的升高而减弱,耐受阈值为0.200EU·mL^(-1);低浓度CQ10-LPSp处理下,未消毒组苜蓿幼苗的抗氧化酶和防御酶活性高于消毒组。研究结果可为脂多糖的开发及诱导紫花苜蓿的先天免疫作用研究提供科学依据。

To clarify the effect of CQ10-LPSp(Pantoea agglomerans CQ10 Lipopolysaccharide,CQ10-LPSp)on antioxidant and defense enzymes of alfalfa seedlings,Medicago sativa‘Juneng 551’was used as the test material.Two seed treatments(disinfection and non-sterilization)and five concentrations(0,0.067,0.134,0.200,and 0.267 EU·mL^(-1))of CQ10-LPSp were interacted with alfalfa to explore the interaction of CQ10-LPSp with alfalfa.Antioxidant activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),and malondialdehyde(MDA)and defense enzyme activities of phenylalanine ammonia lyase(PAL),polyphenol oxidase(PPO),and lipoxygenase(LOX)of CQ10-LPSp in alfalfa seedlings were investigated.With increasing CQ10-LPSp concentration,SOD,POD,PPO,and PAL activities of alfalfa seedlings in the non-sterilized and disinfected groups increased initially and then decreased.With increasing CQ10-LPSp concentration,the MDA content decreased,increased,and decreased again.All activities were significantly lower than that of the control,while CAT activity continued to decrease.When the concentration of CQ10-LPSp was low,activities of CAT,MDA,PAL,and LOX in the non-sterilized seedlings were higher than those in the disinfection group,whereas POD,SOD,and PPO were lower than those in the disinfection group.When the concentration of CQ10-LPSp was high,the non-sterilization CAT and MDA of the seedlings were lower than those in the disinfection group,the POD,SOD,and PAL of the seedlings were higher than those in the disinfection group.A concentration threshold effect on the tolerance of alfalfa seedlings to CQ10-LPSp was demonstrated,and the tolerance of alfalfa seedlings decreased with increasing CQ10-LPSp concentration,with a tolerance threshold of 0.200 EU·mL^(-1).Treatment with lower concentration of CQ10-LPSp resulted in higher activities of antioxidant and defense enzymes of alfalfa seedlings in the non-sterilization group compared to the disinfection group.These results provide a scientific basis for the development of lipopolysaccharides and the study of innate immunity induced in alfalfa.