外源5-氨基乙酰丙酸对干旱胁迫下草珊瑚叶绿素荧光特性及能量分配的影响

目的探讨干旱胁迫对草珊瑚叶绿素荧光特性及能量分配的影响,找到延缓干旱胁迫的方法,为抗旱栽培提供理论依据。方法考察15%PEG-6000模拟干旱胁迫条件下,经过不同浓度5-氨基乙酰丙酸(ALA)和不同时间处理后草珊瑚植株光合色素量、叶绿素荧光参数及能量参数等生理指标的变化。结果外源ALA显著提高了叶绿素a、叶绿素b、总叶绿素和类胡萝卜素的量,提高了最大荧光(Fm)、最大光化学效率(Fv/Fm)、光系统PSII潜在活性(Fv/Fo)、PSII有效光化学效率(Fv′/Fm′)、PSII实际光化学效率(ΦPSII)、光化学淬灭系数(qP)、电子传递率(ETR)和光化学速率(PCR)的水平,有效地降低了初始荧光(Fo),非光化学淬灭系数(NPQ)和热耗散速率(HDR),经过ALA处理后的光化学反应能量(P)所占比例显著升高,天线色素热耗散能量(D)和非光化学耗散能量(E)则表现出相反的趋势,并且P成为能量利用的主要途径,ALA促进了能量合理的再分配。结论 100 mg/L的外源ALA能够通过减少过剩激发能的耗散,提高光合电子传递效率,有效地缓解干旱胁迫对草珊瑚叶片PSII的伤害,提高植株的抗旱能力。

Effects of exogenous 5-aminolevulinic acid on chlorophyll fluorescence characteristics and energy dissipation of Sarcandra glabra under drought stress

Objective To study the effects of drought stress on chlorophyll fluorescence characteristics and energy dissipation of Sarcandra glabra and get the method of alleviating drought stress,so as to provide theoretical basis against drought in planting.Methods Several physiological indexes of S.glabra treated by 5-aminolevulinic acid(ALA) under drought stress(PEG-6000 at the concentration of 15%) were measured,such as the contents of photosynthetic pigment,chlorophyll fluorescence parameters,and energy parameters.Results Exogenous ALA obviously increased the content of chlorophyll and carotenoids,enhanced the maximum fluorescence(Fm),photochemical efficiency of photosystem II(PSII,Fv/Fm),potential photochemical efficiency(Fv/Fo),photochemical efficiency(Fv′/Fm′),PSII actual photochemical efficiency(ΦPSII),photochemical quenching coefficient(qP),electronic transfer rate(ETR),and photochemistry rate(PCR),as well as significnatly decreased the level of minimum fluorescence(Fo),non-photochemical quenching(NPQ) coefficient,and heat dissipation rate(HDR).The proportion of ALA absorbed light in photochemistry(P) was increased,the fraction of antenna pigment heat dissipation(D) and excess energy(E) for NPQ was decreased.The fraction of P was the main pathway for excessive energy dissipation.ALA could promote the redistribution of energy reasonablely.Conclusion Exogenous ALA(100 mg/L) could significantly reduce the dissipation of excess excitation energy,improve the photochemical electron transport efficiency,and efficiently protect leaf blade of S.glabra from PSII damage under drought stress.ALA could obviously promote the drought resistance of S.glabra plantlet.