H2S对盐碱混合胁迫下裸燕麦叶片脂肪酸组成的影响

Effect of Hydrogen Sulfide on Composition of Fatty Acids in Leaves of Naked Oat under Saline-Alkaline Stress

脂肪酸是细胞膜脂的重要组成成分,信号分子硫化氢(H_(2)S)在植物响应盐碱胁迫中发挥着重要作用。为探讨H_(2)S对盐碱混合胁迫下裸燕麦脂肪酸组成的效应,采用盆栽砂培试验,研究了外施H_(2)S供体硫氢化钠(NaHS)和H_(2)S生成抑制剂羟胺(HA)对50mmol·L^(-1)盐碱混合胁迫下裸燕麦品种定莜9号植株生长、叶片细胞膜脂氧化和脂肪酸组成的影响。结果表明:(1)喷施50μmol·L^(-1)NaHS可显著缓解盐碱混合胁迫下定莜9号植株干重的下降和叶片超氧阴离子、过氧化氢和丙二醛含量的提高;增添HA后逆转了喷施NaHS缓解盐碱混合胁迫抑制定莜9号植株生长和叶片膜脂氧化损伤的作用。(2)盐碱混合胁迫导致定莜9号叶片50种脂肪酸中的部分组分含量发生显著改变,使总脂肪酸含量和脂肪酸不饱和程度显著降低。喷施50μmol·L^(-1)NaHS使盐碱混合胁迫下定莜9号叶片5种脂肪酸组分棕榈酸(C16∶0)、岩芹酸(C18∶1N12)、异油酸(C18∶1N7)、亚油酸(C18∶2N6)和α-亚麻酸(C18∶3N3)含量显著降低,其余45种脂肪酸组分含量变化不大;增添HA后5种脂肪酸月桂酸(C12∶0)、反-10-十五烯酸(C15∶1T)、亚油酸(C18∶2N6)、α-亚麻酸(C18∶3N3)和二十三烷酸(C23∶0)含量提高,8种脂肪酸硬脂酸(C18∶0)、反异油酸(C18∶1N7T)、岩芹酸(C18∶1N12)、异油酸(C18∶1N7)、顺-11,14-二十碳二烯酸(C20∶2)、HOMO-γ-亚麻酸(C20∶3N6)、神经酸(C24∶1)和顺-7,10,13,16-二十二碳四烯酸(C22∶4)含量下降,其余37种脂肪酸含量无显著变化。(3)喷施50μmol·L^(-1)NaHS显著降低了盐碱混合胁迫下定莜9号叶片饱和脂肪酸、不饱和脂肪酸和总脂肪酸含量及脂肪酸不饱和度和双键指数,添加HA后显著逆转了NaHS降低不饱和脂肪酸和总脂肪酸含量及脂肪酸不饱和度和双键指数的作用。综上所述,H_(2)S通过降低活性氧积累导致的细胞膜脂氧化损伤和参与脂肪酸组分调控及降低脂肪酸含量和脂肪酸不饱和程度提高裸燕麦适应盐碱胁迫的能力。

Fatty acids are important components of cell membrane lipids,and the signal molecule hydrogen sulfide(H_(2)S) plays an important role in the response of plants to salt-alkali stress. In order to explore the regulatory effect of H_(2)S on the composition of fatty acids in naked oat(Avena nude) under saline-alkali stress,a potted sand culture experiment was conducted to study the effects of applying NaHS(H_(2)S donor) and hydroxylamine(HA,H_(2)S synthesis inhibitor) on the plant growth,leaf cell membrane lipid oxidation and fatty acid composition under 50 mmol·L^(-1) salt-alkali stress. The results showed that spraying 50 μmol·L^(-1) NaHS can significantly alleviate the decrease in dry weight of plants and the increase of superoxide anion,hydrogen peroxide and malondialdehyde contents in leaves of naked oat under salt-alkali stress. The effects of NaHS can be reversed when HA was added. Salt-alkali stress caused significant changes in the content of some components in the 50 fatty acids of naked oat leaves,and significantly reduced the total fatty acid content and the degree of fatty acid unsaturation. Spraying 50 μmol·L^(-1) NaHS significantly reduced the contents of five fatty acid components:palmitate(C16∶0),petroselinate(C18∶1N12),vaccenate(C18∶1N7),linoleate(C18∶2N6) and alphalinolenate(C18∶3N3) in naked oat leaves under salt-alkali stress,yet the contents of the remaining 45 fatty acid components did not change significantly. After adding HA,the contents of five fatty acid components:laurate(C12∶0),10-transpentadecenoate(C15∶1T),linoleate(C18∶2N6),alphalinolenate(C18∶3N3) and tricosanoate(C23∶0) were increased;the contents of eight fatty acid components:stearate(C18∶0),transvaccenate(C18∶1N7T),petroselinate(C18∶1N12),vaccenate(C18∶1N7),11-14eicosadienoate(C20∶2),homogammalinolenate(C20∶3N6),nervonoate(C24∶1) and docosatetraenoate(C22∶4) were decreased,yet the contents of the remaining 37 fatty acid components did not change significantly. Spraying 50 μmol·L^(-1) NaHS significantly reduced the contents of saturated fatty acid,unsaturated fatty acid and total fatty acid,and the unsaturation degree of fatty acids and double bond index in leaves of naked oat under salt-alkali mixed stress. The addition of HA significantly reversed the effect of NaHS in reducing unsaturated fatty acid and total fatty acid content,as well as fatty acid unsaturation and double bond index. The above results indicate that H2S improved the adaptability of naked oats to salt-alkali stress by reducing the lipid oxidative damage of cell membrane induced by the accumulation of reactive oxygen species,participating in the regulation of fatty acid components,and reducing fatty acid contents and fatty acid unsaturation degree in leaves.