摘要
镉(Cd)是最具生物毒性的重金属污染物之一,过氧化氢(H 2 O 2)是参与植物逆境响应调节的信号分子。为探讨H 2 O 2对Cd胁迫下植物生理响应的调控机制,以裸燕麦品种‘定莜6号’为材料,采用砂培方法研究了H 2 O 2外源喷施对50 mg·L-1 Cd 2+胁迫下幼苗生长、叶片叶黄素循环、叶绿素荧光参数和植株Cd积累特性的影响。结果表明:与单独Cd胁迫相比,喷施5 mmol·L-1 H 2 O 2使Cd胁迫下的裸燕麦幼苗根系和地上部干重分别提高了18.5%和26.9%,叶片光系统Ⅱ(PSⅡ)最大光化学效率(F v/F m)、实际光化学效率(ΦPSⅡ)、光化学猝灭系数(qP)、光系统Ⅰ激发能分配系数(α)和吸收光能用于光化学反应的份额(P)分别提高了15.7%、98.6%、61.6%、40.9%和98.6%,叶片叶黄素循环脱环氧化状态(A+Z)/(V+A+Z)、PSⅡ非光化学猝灭系数(NPQ)、调节性能量耗散Y(NPQ)、非调节性能量耗散Y(NO)、PSⅡ激发能分配系数(β)、双光系统间激发能分配不平衡偏离系数(β/α-1)、吸收光能用于天线热耗散的份额(D)和PSⅡ反应中心非光化学耗散的份额(E x)分别下降了11.2%、7.9%、13.9%、12.2%、12.7%、55.2%、19.1%和10.6%。同时,喷施H 2 O 2还使Cd胁迫下裸燕麦幼苗根系Cd含量及根系和地上部Cd积累量分别提高了52.0%、92.4%和25.2%,Cd由根系向地上部的转运率下降了34.4%,但地上部Cd含量没有显著变化。由此表明,外源H 2 O 2可能一方面通过提高PSⅡ光化学效率而非依赖叶黄素循环的热耗散减轻了Cd胁迫诱导的光抑制,另一方面通过增强根系对Cd的滞留和降低Cd由根系向地上部的转运,从而缓解了Cd胁迫对裸燕麦幼苗生长的抑制,提高了裸燕麦对Cd胁迫的耐性。
Cadmium(Cd)is one of the most biotoxic heavy metal pollutants.Hydrogen peroxide(H 2 O 2)is a signaling molecule involved in plant response regulation to different stresses,including heavy metal stress.The objective of this study was to analyze the physiological mechanism of exogenous H 2 O 2 mitigating Cd induced stress damage in naked oat(Avena nuda L.)seedlings.Seedlings of naked oat cultivar‘Dingyou 6’were used in a sand culture experiment to investigate the effect of spraying H 2 O 2 on seedling growth,leaf xanthophyll cycle,chlorophyll fluorescence parameters,and cadmium accumulation characteristics with 50 mg·L-1 Cd 2+treatment.The results showed that Cd exposure depressed plant growth.However,after foliar-spraying with 5 mmol·L-1 H 2 O 2,the dry weights of roots and shoots were increased by 18.5%and 26.9%,respectively.In addition,the PSⅡmaximal ph-otochemistry efficiency(F v/F m),practical photochemical efficiency(ΦPSⅡ),photochemical quenching coefficient(qP),photosynthetic systemⅠexcitation energy distribution coefficient(α),and quotient of absorbed luminous energy used for photochemical action(P)in leaves of naked oat seedlings under Cd stress after foliar-spraying H 2 O 2 increased by 15.7%,98.6%,61.6%,40.9%and 98.6%,respectively,compared with Cd stress treatment alone.The leaf de-epoxidation extent of xanthophyll cycle(A+Z)/(V+A+Z),photosynthetic systemⅡ(PSⅡ)non-photochemical quenching coefficient(NPQ),regulated energy dissipation Y(NPQ),non-regulated energy dissipation Y(NO),PSⅡexcitation energy distribution coefficient(β),unbalanced distribution of coefficient deviation on excitation energy between two photosystems(β/α-1),quotient of absorbed luminous energy used for antenna heat dissipation(D),and quotient of absorbed luminous energy used for non-photochemical dissipation(E x)in reaction center of PSⅡdecreased by 11.2%,7.9%,13.9%,12.2%,12.7%,55.2%,19.1%and 10.6%,respectively.Moreover,the Cd content and accumulation in roots and shoots increased by 52.0%,92.4%and 25.2%,respectively,and the transport rate of Cd from roots to shoots decreased by 34.4%after foliar-spraying H 2O 2 under Cd stress,but there was no significant change in Cd content in shoots.Therefore,foliar-spraying H 2O 2 not only decreased photoinhibition caused by Cd stress through improving PSⅡphotochemical efficiency rather than the xanthophyll cycle-dependent energy dissipation,but also enhanced the immobilization of Cd in roots and reduced its transportation from root to shoot in naked oat seedlings under Cd stress,thus mitigated the inhibition of Cd stress on seedlings growth and enhanced the tolerance of naked oat to Cd stress.
作者
刘建新
欧晓彬
王金成
LIU Jianxin;OU Xiaobin;WANG Jincheng(University Provincial Key Laboratory for Protection and Utilization of Longdong Bio-resources in Gansu Province/College of Life Sciences and Technology,Longdong University,Qingyang,Gansu 745000,China)
出处
《干旱地区农业研究》
CSCD
北大核心
2019年第6期65-71,共7页
Agricultural Research in the Arid Areas
基金
国家自然科学基金项目(31960375)
关键词
过氧化氢(H2O2)
裸燕麦
镉胁迫
叶绿素荧光参数
镉积累特性
hydrogen peroxide
naked oat
Cd stress
chlorophyll fluorescence parameter
cadmium accumulation characteristics
