外源Spd对渗透/盐胁迫下草莓生理生化的影响

Effects of exogenous spermidine on the physiological and biochemical parameters of strawberry under osmotic or salt stress

【目的】了解外源亚精胺(Spermidine,Spd)对渗透与盐胁迫下草莓幼苗叶片生理生化的影响。【方法】草莓采用水培方式在人工气候室内培养,试验设计6个处理水平:CK(对照,无胁迫)、DS(中度干旱胁迫,10%PEG-6000)、SS(重度盐胁迫,100 mM NaCl)、CK+Spd(无胁迫,根系添加0.25 mM Spd)、DS+Spd(10%PEG-6000,根系添加0.25 mM Spd)和SS+Spd(100 mM NaCl,根系添加0.25 mM Spd),并分别测定0 h、0.5 h、2 h、8 h、24 h的草莓叶片气体交换参数和生理生化指标。【结果】在渗透与盐胁迫初始阶段,外源Spd预处理能够促进草莓叶片腐胺(Putrescine,Put)的诱导积累及其向Spd与精胺(Spermine,Spm)转化,并促进了脯氨酸(Proline,Pro)含量的升高;至逆境胁迫24 h时,外源Spd预处理的渗透/盐胁迫下草莓叶片中Put/(Spd+Spm)比值比CK(0.32±0.02)分别降低了28.1%和21.9%,而未添加外源Spd预处理的渗透/盐胁迫下草莓叶片Put/(Spd+Spm)比值仅比CK下降了15.6%和6.3%。在渗透/盐胁迫下,外源Spd预处理促进了草莓叶片Put积累的同时,显著抑制了过氧化氢(H_(2)O_(2))的产生速率,明显降低了丙二醛(Malondialdehyde,MDA)的含量,并且显著提高了草莓叶片的气孔导度(Gs)、净光合速率(Pn)和蒸腾速率(Tr)。此外,在无胁迫时(CK),外源Spd预处理同样也可以促进草莓叶片PAs和Pro的诱导积累,降低草莓叶片的H_(2)O_(2)与MDA含量,提高叶片的Pn和Tr。【结论】外源Spd预处理促进了草莓叶片内源PAs及Pro的积累,增强了渗透与盐胁迫下草莓的抗逆性。

[Objective]The aim of this present study is to determine the effects of exogenous spermidine(Spd)on the physiological and biochemical parameters in strawberry leaves under osmotic or salt stress.[Methods]Strawberry plant seedlings were planted in a smart phytotron by hydroponics.The experimental design included six treatments:(a)CK;Control group(No stress),(b)DS;Moderate drought stress(10%PEG-6000),(c)SS;Severe salt stress(100 mM NaCl),(d)CK+Spd;0.25 mM Spd,(e)DS+Spd;10%PEG-6000+0.25 mM Spd,(f)SS+Spd;100 mM NaCl+0.25 mM Spd.The gas exchange parameters and the physiological and biochemical indexes of strawberry leaves were measured at 0 h,0.5 h,2 h,8 h,and 24 h,respectively.[Results]The results showed that exogenous Spd pretreatment of strawberry roots could promote the induced accumulation of putrescine(Put)and its transformation to Spd and spermine(Spm)in strawberry leaves,and increase the content of proline(Pro)in the initial stage of osmotic/salt stress.At 24 h of stress,the ratio of Put/(Spd+Spm)in strawberry leaves with exogenous Spd pretreatment of strawberry roots under osmotic/salt stress was 28.1%and 21.9%lower than that of CK(0.32±0.02),respectively;However,the ratio of Put/(Spd+Spm)in strawberry leaves under osmotic/salt stress without exogenous Spd pretreatment decreased by 15.6%and 6.3%than that of CK,respectively.Under osmotic/salt stress,exogenous Spd pretreatment promoted Put accumulation in strawberry leaves,inhibited the rate of hydrogen peroxide(H_(2)O_(2))generation,as well as decreased malondialdehyde(MDA)content,concurrent with the rise in stomatal conductance(Gs),net photosynthetic rate(Pn)and transpiration rate(Tr).In addition,under no stress(CK),the exogenous Spd pretreatment could also promote the accumulation of Polyamines(PAs)and Pro in strawberry leaves,reduce the contents of H_(2)O_(2)and MDA,and increase Pn and Tr.[Conclusion]Exogenous Spd pretreatment promoted the accumulation of endogenous PAs and Pro in strawberry leaves,and thus enhanced the stress resistance of strawberries under osmotic or salt stress.