通过叶反射和叶绿素荧光分析同步测量的光合行为评价
Summary
我们描述了一种研究高植物的光合反应的新方法,包括使用PAM和光谱辐射计同时测量叶绿素荧光和叶反射率,以检测来自在阿拉伯的叶子面积相同。
Abstract
叶绿素荧光分析被广泛用于测量完整植物的光合行为,并产生了许多能有效测量光合作用的参数。叶反射率分析提供了生态和农业中的几个植被指数,包括光化学反射率指数(PRI),该指数可用作光合作用期间热能量耗散的指标,因为它与非光化学淬火(NPQ)。但是,由于 NPQ 是复合参数,因此需要验证 NPQ 以了解 PRI 参数的性质。为了获得评价PRI参数的生理证据,我们同时测量了桑索菲尔循环缺陷突变体(npq1)和野生型阿拉伯霉菌植物的叶绿素荧光和叶反射率。此外,qZ参数,可能反映xanthophyll周期,是从叶绿素荧光分析的结果中提取的,通过监测NPQ的松弛动力学关闭后。这些同步测量使用脉冲振幅调制(PAM)叶绿素荧光计和光谱辐射计进行。两个仪器的光纤探头彼此靠近,以检测来自同一叶片位置的信号。利用外部光源激活光合作用,从PAM仪器提供测量灯和饱和光。该实验系统使我们能够监测完整植物中光依赖性PRI,并发现PRI的轻依赖性变化在野生型和npq1突变体之间存在显著差异。此外,PRI 与 qZ 密切相关,这意味着 qZ 反映了 xanthophyll 周期。这些测量表明,同时测量叶片反射率和叶绿素荧光是参数评估的有效方法。
Introduction
叶反射率用于远程感应植被指数,反映植物1、2中的光合作用或特征。基于红外反射信号的标准化差植被指数(NDVI)是探测叶绿素相关特性的最广为人知的植被指数之一,在生态学和农业科学中作为树木或作物的环境反应指标3。在实地研究中,虽然许多参数(如叶绿素指数、水指数等)已经得到开发和使用,但很少详细核实这些参数是否直接(或间接)检测过使用突变体。
叶绿素荧光的脉冲振幅调制(PAM)分析是测量光合反应和光系统II(PSII)4中涉及的过程的有效方法。叶绿素荧光可以通过相机检测,并用于筛选光合作用突变体5。然而,对叶绿素荧光的相机检测需要复杂的方案,如暗处理或光饱和脉冲,这在实地研究中很难实现。
叶吸收的太阳能主要消耗光合反应。相比之下,吸收多余的光能会产生活性氧,从而对光合分子造成损害。多余的光能必须通过非光化学淬火(NPQ)机制6作为热量消散。光化学反射指数(PRI)反映叶片反射参数的光线相关变化,来自531和570nm(参考波长)7、8的窄带反射率。据报道,在叶绿素荧光分析9中,它与NPQ相关。但是,由于 NPQ 是一个复合参数,包括 xanthophyll 周期、状态传统和光抑制,因此需要详细验证以了解 PRI 参数的度量。我们专注于黄体素循环,一种热耗散系统,涉及黄藻素颜料的脱氧抗氧化(葡萄松素对安他拉桑辛和玉米黄素),以及NPQ的主要成分,因为PRI和这些的转换之间的相关性颜料在以前的研究中已经报道8。
许多光合作用相关的突变体在阿拉伯经体中被分离和鉴定。npq1突变体不积累玉米黄素,因为它携带一个突变在葡萄松素脱环酶(VDE),催化葡萄松素转化为玉米黄素10。为了确定PRI是否只检测桑索植物色素的变化,我们同时测量了NPq1和野生型同一叶区的PRI和叶绿素荧光,然后在暗松弛的不同时间尺度上解剖NPQ,以提取与xanthophyll相关的组分11。这些同步测量为植被指数的分配提供了宝贵的技术。此外,由于 PRI 与总初级生产率 (GPP) 相关,因此将 PRI 精确分配给一个组件的能力在生态学12中具有重要的应用价值。
Protocol
Representative Results
Discussion
在这项研究中,我们获得了额外的证据,表明PRI通过同时测量叶绿素荧光和叶反射率来代表桑索菲尔颜料。
具有类似阳光波长的卤素光被改编为活动光源,以激活光合作用。我们最初使用白色 LED 光源来避免叶表面的热损伤,但这会产生缓慢的暗松弛动力学和异常高的 qI(光抑制淬火),可能通过光损伤 PSII。因此,我们使用内置冷过滤器对卤素灯进行了改造,以减少热量产生。此光源在?…
Divulgations
The authors have nothing to disclose.
Acknowledgements
我们感谢东北大学(Koki Hikosaka博士)鼓励讨论、协助工作空间和实验工具。这项工作部分得到了KAKENHI[赠款编号18K05592,18J40098]和奈藤基金会的支持。
Materials
| Halogen light source | OptoSigma | SHLA-150 | |
| Light quantum meter | LI-COR | LI-1000 | |
| PAM chlorophyll fluorometer | Walz | JUNIOR-PAM | |
| PAM controliing software | Walz | WinControl-3.27 | |
| Reflectance standard | Labsphere, Inc. | SRT-99-050 | |
| Spectral radiometer | ADS Inc. | Field Spec3 | |
| Spectral radiometer controlling software | ADS Inc. | RS3 |
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