外源NO对冷害胁迫下酸枣种子萌发和幼苗叶片AsA-GSH的影响

Effects of exogenous NO on seed germination and AsA-GSH in leaves of Zizyphus jujuba seedlings under cold stress

通过人工室内模拟冷害逆境胁迫,采用外源0.1、0.2、0.5 mmol/L一氧化氮(Nitric oxide,NO)供体亚硝基铁氰化钠(硝普钠,SNP)和0.5 mmol/L NO合成酶抑制剂(L-NAME)、硝酸还原酶非专一性抑制剂(NaN3)及NO清除剂(cPTIO)对酸枣(Zizyphus jujuba Mill)种子和幼苗叶片进行处理,研究其对冷害胁迫下酸枣种子发芽特性和幼苗抗坏血酸-谷胱甘肽(AsA-GSH)循环系统的影响,为外源NO在未来酸枣抗逆生产中的广泛应用提供理论基础.结果表明:4℃冷害胁迫下,酸枣种子萌发和幼苗生长受到抑制,在施加不同浓度的SNP后能显著增加冷害逆境下酸枣种子的发芽率、发芽势、发芽指数和活力指数,降低幼苗叶片丙二醛(MDA)和过氧化氢(H2O2)含量,同时使脯氨酸(Pro)含量增加,抗坏血酸(AsA)、谷胱甘肽(GSH)含量和抗氧化酶活性[抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、脱氢抗坏血酸还原酶(DHAR)和单脱氢抗坏血酸还原酶(MDAR)]显著升高.上述表明外源NO可缓解冷害胁迫对酸枣种子萌发及幼苗生长的抑制作用,且以0.5 mmol/L SNP对冷害逆境的缓解效果最佳,而采用NO清除剂和两种合成抑制剂处理明显减弱NO缓解冷害胁迫的效果.(图7表2参41)

Zizyphus jujuba leaves were treated with the exogenous NO donor(sodium nitroferricyanide(Ⅲ)dehydrate/sodium nitroprusside,SNP at 0.1,0.2,0.5 mmol/L),an nitric oxide synthase inhibitor(L-NAME),a nitrate reductase non-specific inhibitor(NaN3)and nitric oxide scavenger(cPTIO)to study their effects on the germination of seeds and the circulation of ascorbate glutathione(AsA-GSH)circulation system during cold stress.We also aimed to provide a theoretical basis for the extensive application of exogenous nitric oxide(NO)in protecting Z.jujuba against cold stress.Temperatures of 4℃ inhibited the seed germination and seedling growth of Z.jujuba.Applying different concentrations of SNP significantly increased the germination rate,germination potential,germination index and vigor index of Z.jujuba seeds.SNP also decreased the contents of malondialdehyde(MDA)and hydrogen peroxide(H2O2)in seedling leaves.At the same time,proline(Pro),ascorbic acid(AsA),glutathione(GSH)content and antioxidant enzyme activities[ascorbic peroxidase(APX),glutathione reductase(GR),dehydroascorbate reductase(DHAR)and monodehydroascorbate reductase(MDAR)]were significantly increased.In conclusion,exogenous NO could alleviate the inhibitory effect of cold stress on the seed germination and seedling growth of Z.jujuba,reduce membrane lipid peroxidation caused by cold stress,maintain the stability of AsA-GSH circulatory system,and enhance cold resistance.The optimum concentration of SNP for negating the effects of cold stress was 0.5 mmol/L.When the NO scavenger and two synthetic inhibitors were used,the germination of Z.jujuba seeds after NO treatment was inhibited under cold stress.Furthermore,the parameters of membrane lipid peroxidation of seedlings were decreased and the indices of antioxidant enzymes and antioxidant activity were increased.The effect of NO on seed germination and the growth of Z.jujuba seedlings under cold stress were significantly weakened,which further demonstrated the protective effects of NO on Z.jujuba seeds and seedlings under cold stress.