Photoinactivation of photosystem II complexes and photoprotection by non-functional neighbours in Capsicum annuum L. leaves
Photoinactivation of photosystem II complexes and photoprotection by non-functional neighbours in Capsicum annuum L. leaves
复制标题
DOI：
10.1007/s004250000398
复制
发表时间：
2001-02-01
期刊：
影响因子：
4.3
通讯作者：
Chow, WS
中科院分区：
文献类型：
--
作者：
Lee, HY;Hong, YN;Chow, WS
将在100 μmol光子m⁻²s⁻¹（低光强）或500 μmol光子m⁻²s⁻¹（高光强）下生长的辣椒（Capsicum annuum）植株的叶片切段在三种辐照度和三种温度下光照数小时。在不同时间，通过叶绿素荧光参数（1/Fₒ - 1/Fₘ，其中Fₒ和Fₘ分别是对应于开放和关闭的光系统II（PS II）陷阱的荧光产量）测量功能性光系统II复合物的剩余比例CR，该参数又通过每次饱和单周转闪光的产氧量进行校准。在存在林可霉素（一种叶绿体编码蛋白质合成抑制剂）的情况下对叶片切段进行光照时，从1.0下降到约0.3是单指数的。此后，f下降得慢得多，剩余比例（约0.2）能够在长时间光照下存活。这些结果可以解释为支持这样一种假说，即光失活的PS II复合物对功能性相邻复合物具有光保护作用（G. Oquist等人，1992年，《植物》186：450 - 460），前提是假设光失活的PS II最初只是激发能的弱猝灭剂，但在长时间光照下，当相当一部分PS II复合物也被光失活时，它会变成强得多的猝灭剂。在不存在林可霉素的情况下，PS II的光失活和修复同时发生，使得f达到一个由处理辐照度、温度和生长辐照度决定的稳态值。根据一个简单的动力学模型对在有和没有林可霉素存在的情况下获得的结果进行分析，该模型正式包含了从弱猝灭剂到强猝灭剂的转变，得出了各种条件下光失活和修复的速率系数，并深入了解了f对光失活速率系数的影响。它们表明，该方法是使用放射性标记氨基酸定量叶片中PS II光失活和修复的一种方便的替代方法。
Leaf segments from Capsicum annuum plants grown at 100 mu mol photons m(-2)s(-1) (low light) or 500 mu mol photons m(-2)s(-1) (high light) were illuminated at three irradiances and three temperatures for several hours. At various times, the remaining fraction CR of functional photosystem II (PS II) complexes was measured by a chlorophyll fluorescence parameter (1/F-o - 1/F-m, where F-o and F-m are the fluorescence yields corresponding to open and closed PS II traps, respectively), which was in turn calibrated by the oxygen yield per saturating single-turnover flash. During illumination of leaf segments in the presence of lincomycin, an inhibitor of chloroplast-encoded protein synthesis, the decline off from 1.0 to about 0.3 was mono-exponential. Thereafter, f declined much more slowly, the remaining fraction (approximate to0.2) being able to survive prolonged illumination. The results can be interpreted as being in support of the hypothesis that photoinactivated PS II complexes photoprotect functional neighbours (G. Oquist et al. 1992, Planta 186: 450-460), provided it is assumed that a photoinactivated PS II is initially only a weak quencher of excitation energy, but becomes a much stronger quencher during prolonged illumination when a substantial fraction of PS II complexes has also been photoinactivated. In the absence of lincomycin, photoinactivation and repair of PS II occur in parallel, allowing f to reach a steady-state value that is determined by the treatment irradiance, temperature and growth irradiance. The results obtained in the presence and absence of lincomycin are analysed according to a simple kinetic model which formally incorporates a conversion from weak to strong quenchers, yielding the rate coefficients of photoinactivation and of repair for various conditions, as well as gaining an insight into the influence off on the rate coefficient of photoinactivation. They demonstrate that the method is a convenient alternative to the use of radiolabelled amino acids for quantifying photoinactivation and repair of PS II in leaves.