THE SPATIAL-DISTRIBUTION OF CHLOROPLAST WATER IN ACER-PLATANOIDES SUNAND SHADE LEAVES

We evaluated a new, two-dimensional (2-D) nuclear magnetic resonance ( NMR) imaging technique as a method for measuring the distribution of c hloroplasts in leaves. NMR images that showed the distribution of chlo roplast water and of total water as a function of depth into Acer plat anoides sun and shade leaves were compared with the distribution of ch lorophyll in the same leaf types (as measured by fluorescence microsco py), with the cellular structure (by scanning electron microscopy), an d with published information. Results showed that the volume fraction of chloroplast water was much larger in shade than in sun leaves, and that it averaged about one-third larger in the palisade than in the sp ongy parenchyma region of both leaf types. Chlorophyll fluorescence wa s more intense in shade than in sun leaves. In sun leaves, fluorescenc e was maximal in the palisade region near the junction with the spongy parenchyma, while in shade leaves, fluorescence was maximal in the up per part of the spongy layer. We concluded that 2-D NMR imaging reliab ly indicates the location of chloroplast water.