Haber A H, Thompson P J, Walne P L, Triplett L L
Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830.
Plant Physiol. 1969 Nov;44(11):1619-28. doi: 10.1104/pp.44.11.1619.
Excised apical portions of green wheat leaf sections were treated with aminotriazole to prevent formation of new chloroplasts. Illumination retarded the decline in chlorophyll content per leaf section, the disintegration of chloroplast ultrastructure, and the loss of capacity for photosynthetic carbon fixation. We interpret these 3 effects of illumination as facets of a single light effect in retarding chloroplast senescence. This light effect in retarding chloroplast senescence has features differing from characteristics of photosynthetic carbon fixation. For example, A) application of the photosynthetic inhibitor 3-(3,4-dichlorophenyl)-1, 1-dimethylurea did not decrease, and may have even slightly increased, the effectiveness of light; B) although the action spectrum contains peaks in the blue and red regions, it differs from the action spectrum for photosynthetic CO(2) assimilation in wheat; C) in nonphotosynthesizing tissue, application of sugars did not retard chloroplast senescence; D) light saturation was achieved by only a few hundred microwatts/cm(2). Considered together with the well-known light requirement for chloroplast formation, our results indicate that light has a dual, photomorphogenetic control in maintaining the green status of the plant by also exerting a second effect: retarding of senescence of chloroplasts already present.
将绿色小麦叶片切段的顶端部分切除，用氨基三唑处理以防止新叶绿体的形成。光照延缓了每个叶片切段叶绿素含量的下降、叶绿体超微结构的解体以及光合碳固定能力的丧失。我们将光照的这三种效应解释为延缓叶绿体衰老的单一光效应的不同方面。这种延缓叶绿体衰老的光效应具有与光合碳固定特性不同的特点。例如，A）施用光合抑制剂3-(3,4-二氯苯基)-1,1-二甲基脲并没有降低，甚至可能略微增加了光照的有效性；B）虽然作用光谱在蓝光和红光区域有峰值，但它与小麦光合CO₂同化的作用光谱不同；C）在非光合组织中，施用糖类并不能延缓叶绿体衰老；D）仅几百微瓦/平方厘米就能达到光饱和。结合众所周知的叶绿体形成对光的需求，我们的结果表明，光在维持植物绿色状态方面具有双重光形态发生控制作用，还发挥了第二种作用：延缓已存在叶绿体的衰老。
