低温胁迫对结缕草抗氧化酶活性和脂肪酸含量的影响

Effects of Low Temperature Stress on the Antioxidant Enzyme Activities and Fatty Acid Contents in Zoysiagrass

为探讨不同纬度来源结缕草(Zoysia Willd)对低温的响应,本研究以两份结缕草种质LT-40(高纬度)和LT-22(低纬度)为材料,分析了适温(30℃/25℃)、亚适温(18℃/12℃)、冷害(8℃/2℃)和冻害(2℃/—4℃)4种温度对叶片电导率(Electrolyte leakage,EL)、叶绿素和丙二醛(Malondialdehyde,MDA)含量、抗氧化酶活性、叶片脂肪酸含量及不饱和指数的影响。结果表明,随着温度的降低,EL增大,叶片中叶绿素含量降低、MDA含量升高,且在LT-22中变化更大;叶片超氧化物歧化酶、过氧化物酶、过氧化氢酶活性均随着温度的下降而逐渐升高,且在LT-40中表现更为显著;低温下叶片中棕榈酸含量呈下降趋势,而硬脂酸含量只在LT-40叶片中显著下降,棕榈油酸和油酸含量在LT-40叶片中显著低于对照,而亚麻酸含量在LT-40叶片中却显著高于对照,不饱和指数在LT-40叶片中显著高于对照。高纬度来源的结缕草在低温胁迫下具有较高的抗氧化能力和较好的质膜稳定性,因而其耐寒性更好。

In order to investigate the effect of low temperature stress on the leaf electrolyte leakage(EL),chlorophyll content,malondialdehyde(MDA)content,antioxidant enzyme activity(SOD,POD,CAT),fatty acid content and index of unsaturated fatty acid,two genotypes of zoysiagrass originated from different latitudes,LT-40(from high latitude)and LT-22(from low latitude)were selected and treated under a range of temperatures:optimum(30℃/25℃),suboptimum(18℃/12℃),chilling(8℃/2℃)and freezing(2℃/-4℃)under environment-controlled growth chambers.The results demonstrated that leaf electrolyte leakage and MDA content increased and chlorophyll content decreased with the reduction of temperature,with greater changes in LT-22 than in LT-40;the leaf SOD,POD and CAT activity increased with the decline of temperature,with greater increasing in LT-40 than in LT-22,suggesting that zoysiagrass originated from high latitude exhibited a higher cold tolerance than the lower latitude one.The content of saturated fatty acids,palmitic acid decreased in both genotypes while the stearic acid decreased only in LT-40 under low temperature stress.The unsaturated fatty acids,palmitoleic acid,oleic acid and linolenic acid contents had no significant changes in LT-22 under low temperature stress,whereas for LT-40,the palmitoleic acid and oleic acid contents significantly decreased under freezing temperature stress as compared with the control.The index of unsaturated fatty acid increased with the reduction of temperature in LT-40,particularly under chilling and freezing temperature,but had no changes for LT-22 under low temperature.These results indicated that the greater cold tolerance for the zoysiagrass originated from higher latitude may be due to the increased unsaturated fatty acid and index of unsaturated fatty acid that lead to the stability of membranes under low temperature stress.