外源ALA对盐胁迫下西伯利亚白刺光合作用的影响

Effect of exogenous ALA on photosynthesis of Nitraria sibirica Pall.during salt stress

为探究外源5-氨基乙酰丙酸(ALA)对盐生植物耐盐调节机理,以西伯利亚白刺为试验材料,研究0、200和400 mmol·L^-1盐胁迫下施加0、30和60 mg·L^-1 ALA对西伯利亚白刺叶片叶绿素含量(Chl)、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间二氧化碳浓度(Ci)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)、光化学淬灭系数(qP)、非光化学淬灭系数(NPQ)及表观电子传递效率(ETR)的影响。结果表明,在不施加外源ALA情况下,低浓度NaCl(200 mmol·L^-1)处理可提高西伯利亚白刺叶片Chl、Pn、Gs、Tr、Fv/Fm、ΦPSⅡ、qP、ETR,降低Ci、NPQ;高浓度NaCl(400 mmol·L^-1)处理下,Chl、Pn、Gs、Tr、Fv/Fm、ΦPSⅡ、qP、ETR降低且低于0 mmol·L^-1 NaCl处理,Ci、NPQ升高且高于0 mmol·L^-1 NaCl处理。与不施加ALA相比,施加30 mg·L^-1 ALA对NaCl胁迫下西伯利亚白刺叶片Chl、Pn、Gs、Tr、Fv/Fm、ΦPSⅡ、qP、ETR有明显促进作用,施加60 mg·L^-1 ALA促进效果不明显,出现不同程度抑制作用。说明低浓度NaCl时,施加一定浓度ALA可有效缓解NaCl胁迫对西伯利亚白刺光合作用的影响,高浓度NaCl时外施ALA缓解作用不明显,高浓度ALA甚至对光合作用表现抑制作用。

Nitralia sibiria Pall.seedlings were used as experiment materials to investigate the mechanism of exogenous 5-aminolevulinic acid(ALA)on salt tolerance in halophytes.The effects of different concentrations of exogenous ALA(0,30,and 60 mg·L^-1)on chlorophyll content(Chl),net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs),cell carbon dioxide concentration(Ci),PSII maximum photochemical efficiency(Fv/Fm),PSII actual photochemical efficiency(ΦPSII),photochemical quenching coefficient(qP),non-photochemical quenching coefficient(NPQ)and apparent electron transfer efficiency(ETR)under different concentrations of salt stress(0,200 and 400 mmol·L^-1)were studied.Chl,Pn,Gs,Tr,Fv/Fm,ΦPSII,qP and ETR increased while Ci and NPQ declined under low concentration NaCl(200 mmol·L^-1)stress without the application of exogenous ALA.Under high concentration NaCl(400 mmol·L^-1)stress,Chl,Pn,Gs,Tr,Fv/Fm,ΦPSII,qP and ETR decreased and were lower than those of the control.However,Ci and NPQ increased and were higher than those of the control.Exogenous application of 30 mg·L^-1 ALA significantly promoted Chl,Pn,Gs,Tr,Fv/Fm,ΦPSII,qP and ETR under NaCl stress as compared to the treatments in the absence of ALA.However,60 mg·L^-1 ALA showed insignificant,even inhibition effects of different degrees on the photosynthesis of N.sibiria.The above results demonstrated that exogenous application of ALA effectively alleviated the inhibition effects on the photosynthesis of N.sibiria under low concentration NaCl stress.However,the alleviation effects of ALA on high concentration NaCl stress were not obvious.High concentration ALA even inhibited the photosynthesis of N.sibiria under high concentration NaCl stress.