Department of Plant Sciences, The University of Western Ontario, N6A 5B7, London, Ontario.
Photosynth Res. 1987 Jan;14(2):97-112. doi: 10.1007/BF00032315.
Chloroplast biogenesis during continuous illumination at either low, cold-hardening temperatures (5°C) or non-hardening temperatures (20°C) was examined by monitoring the etioplast-chloroplast transformation with respect to pigment accumulation and the development of PSI- and PSII-associated electron transport activities in winter rye (Secale cereale L. cv Puma). Generally, chlorophyll and carotenoid accumulation during greening at 20°C were characterized by rapid initial rates in contrast to pronounced, initial lag times during biogenesis at 5°C. Although greening temperature had no effect on the sequential appearance of PSI relative to PSII, greening temperature significantly altered the pattern of appearance of PSI relative to chlorophyll accumulation. Thylakoid biogenesis under continuous illumination at 20°C imposed a pattern whereby the development of PSI activity was antiparallel to chlorophyll accumulation. In contrast, the development of PSI activity under continuous illumination at 5°C was paralllel to chlorophylll accumulation. These developmental patterns were independent of the temperature experienced during etiolation. However, rye seedlings etiolated at 20°C and subsequently subjected to continuous illumination at 5°C exhibited a 70% reduction in the maximum PSII activity (100 μmol DCPIP reduced.mg Chl(-1).h(-1)) attained relative to that observed for similar etiolated seedlings greened at 20°C (300 μmol DCPIP reduced.mg Chl(-1).h(-1)). This low temperature-induced inhibition could be alleviated by an initial 2 h exposure to continuous light at 20°C prior to greening to 5°C. Rye seedlings etiolated at 5°C attained similar maximal PSII activities (300 μmol DCPIP reduced.mg Chl(-1).h(-1)) regardless of the greening temperature. We suggest that the altered kinetics for pigment accumulation, the low temperature-induced change in the pattern for the appearance of PSI activity relative to chlorophyll accumulation and the differential sensitivity of 20° and 5° etiolated seedlings to greening temperature reflect an alteration in membrane organization incurred as a consequence of thylakoid assembly at low temperature.
在 5°C（低温冷驯化温度）或 20°C（非冷驯化温度）的连续光照下，通过监测质体-叶绿体转化过程中色素的积累以及 PSI 和 PSII 相关电子传递活性的发展，研究了叶绿体生物发生。一般来说，在 20°C 下进行绿化时，叶绿素和类胡萝卜素的积累表现出快速的初始速率，而在 5°C 下进行生物发生时则表现出明显的初始滞后时间。尽管绿化温度对 PSI 相对于 PSII 的出现顺序没有影响，但绿化温度显著改变了 PSI 相对于叶绿素积累的出现模式。在 20°C 的连续光照下，类囊体的生物发生形成了一种模式，即 PSI 活性的发展与叶绿素的积累相反。相比之下，在 5°C 的连续光照下，PSI 活性的发展与叶绿素的积累平行。这些发育模式与黄化过程中经历的温度无关。然而，在 20°C 下黄化然后在 5°C 下连续光照的黑麦幼苗，其 PSII 最大活性（100 μmol DCPIP 还原.mg Chl(-1).h(-1)）比在 20°C 下进行相同黄化处理的幼苗观察到的活性降低了 70%（300 μmol DCPIP 还原.mg Chl(-1).h(-1)）。这种低温诱导的抑制可以通过在绿化为 5°C 之前先在 20°C 下连续光照 2 小时来缓解。在 5°C 下黄化的黑麦幼苗无论绿化温度如何，都能达到相似的最大 PSII 活性（300 μmol DCPIP 还原.mg Chl(-1).h(-1)）。我们认为，色素积累的动力学变化、PSI 活性相对于叶绿素积累出现模式的低温诱导变化以及 20°C 和 5°C 黄化幼苗对绿化温度的敏感性差异，反映了由于在低温下进行类囊体组装而导致的膜组织发生的改变。
