外源硫化氢对干旱胁迫下萌发水稻种子抗氧化代谢的影响

【目的】探讨外源硫化氢(H2S)对干旱胁迫下萌发水稻种子抗氧化代谢的影响及水稻抗旱性内在机制,为提高水稻抗旱能力提供参考依据。【方法】以0.75 mmol/L硫氢化钠(Na HS)为外源H2S供体,用聚乙二醇(PEG)为干旱胁迫模拟剂,以羟胺(HA)为H2S合成抑制剂,检测干旱胁迫下外源H2S处理后水稻种子的发芽率、发芽势、相对电导率和丙二醛(MDA)、可溶性蛋白、过氧化氢(H2O2)含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性。【结果】干旱胁迫下,经Na HS处理的水稻种子发芽率为82.30%、发芽势为43.10%,均显著高于未经Na HS处理的种子(P0.05);可有效阻止水稻种子可溶性蛋白含量减少,降低渗透势,缓解干旱胁迫引起的伤害;可有效缓解水稻种子中H2O2的累积,有利于减缓细胞衰老和解体;可较好地维持水稻种子萌发过程中质膜的稳定性,有利于减轻干旱引起的伤害;可有效降低水稻种子的MDA含量,降低质膜透性;可促进水稻种子萌发过程中SOD、POD、CAT和APX活性的增加,提高萌发水稻种子应对干旱的能力。【结论】经外源H2S供体Na HS处理可显著提高水稻种子的抗氧化酶活性,有效清除活性氧,降低质膜透性,缓解氧化伤害,提高水稻种子的抗旱性,最终有效促进干旱胁迫下水稻种子萌发。

Effects of exogenous hydrogen sulfide on antioxidant metabolism of rice seed germinated under drought stress

Objective]The effects of exogenous hydrogen sulfide(H2S) on antioxidant metabolism of rice seeds germinated under drought stress and intrinsic mechanism of rice drought resistance were explored,so as to provide reference for improving drought resistance of rice.Method]0.75 mmol/L hydrosulfide sodium was used as exogenous H2S donor,polyethylene glycol (PEG) as the drought stress simulated agent,and hydroxylamine (HA) as H2S synthesis inhibitor.Germination rate,germination potential,relative conductivity,malondialdehyde (MDA),soluble protein content,hydrogen peroxide content (H2O2),superoxide dismutase (SOD) activity,catalase (CAT) activity,peroxidase (POD) activity and ascorbate peroxidase(APX) activity of rice seeds treated with exogenous H2S under drought stress were determined.Result]The germination rate and germination potential of rice seeds treated with NaHS were 82.30％ and 43.10％ respectively,which were significantly higher than those of untreated seeds(P＜0.05).Exogenous H2S could effectively prevent the soluble protein content of rice seeds under drought stress from decreasing,lower osmotic potential,alleviate the harm caused by drought stress.It could effectively alleviate H2O2 accumulation in rice seeds,which helped to slow down cell senescence and disintegration.It also better maintained the stability of plasma membrane of rice seed during germination and alleviate the damage caused by drought.Exogenous H2S effectively reduced MDA content in rice seed,decreased permeability of plasma membrane;it also promoted the increase of SOD activity,POD activity,CAT activity and APX activity of rice during germination,and improved the ability of germinated rice seed countering drought.Conclusion]The treatment with exogenous H2S donor NaHS can significantly improve the activity of antioxidant enzymes in rice seeds,effectively remove reactive oxygen,reduce permeability of plasma membrane,alleviate oxidative damage,improve drought resistance of rice seeds,and effectively promote rice seed germination under drought stress finally.