CSIRO Division of Horticultural Research, G.P.O. Box 350, Adelaide, South Australia 5001.
Plant Physiol. 1986 Jun;81(2):708-10. doi: 10.1104/pp.81.2.708.
Absolute DNA amounts of individual chloroplasts from mesophyll and epidermal cells of developing spinach leaves were measured by microspectrofluorometry using the DNA-specific stain, 4,6-diamidino-2-phenyl indole, and the bacterium, Pediococcus damnosus, as an internal standard. Values obtained by this method showed that DNA amounts of individual chloroplasts from mesophyll cells fell within a normal distribution curve, although mean DNA amounts changed during leaf development and also differed from the levels in epidermal chloroplasts. There was no evidence in the data of plastids containing either the high or low levels of DNA which would be indicative of discontinuous polyploidy of plastids, or of division occurring in only a small subpopulation of chloroplasts. By contrast, the distribution of nuclear DNA amounts in the same leaf tissues in which cell division was known to be occurring showed a clear bimodal distribution. We consider that the distribution of chloroplast DNA in the plastid population shows that there is no S-phase of chloroplast DNA synthesis, all chloroplasts in the population in young leaf cells synthesize DNA, and all chloroplasts divide.
采用微分光荧光光度计，使用 DNA 特异性染料 4,6-二脒基-2-苯基吲哚（4,6-diamidino-2-phenyl indole），并以细菌小球菌（Pediococcus damnosus）作为内标，测量发育中叶菠菜叶肉细胞和表皮细胞中单个叶绿体的绝对 DNA 含量。该方法获得的数值表明，尽管叶绿体的平均 DNA 含量在叶片发育过程中发生了变化，并且与表皮叶绿体中的水平也不同，但单个叶绿体的 DNA 含量呈正态分布曲线。数据中没有证据表明存在高或低水平 DNA 的质体，这表明质体的不连续多倍体或仅在一小部分叶绿体中发生分裂。相比之下，在同一叶组织中发生细胞分裂的情况下，核 DNA 含量的分布显示出明显的双峰分布。我们认为，叶绿体群体中叶绿体 DNA 的分布表明没有叶绿体 DNA 合成的 S 期，年轻叶细胞中的所有叶绿体都在合成 DNA，并且所有的叶绿体都在分裂。
