[The immunogold localization of Rubisco and its activase in chloroplasts of barley and maize leaves].

Cellular localization of Rubisco and Rubisco activase (RCA) in the C(3) plant barley (Hordeum vulgare L.) and the C(4) plant maize (Zea mays L.) leaves was investigated using immunogold-labeling electron microscopy. The results showed that the leaf anatomy and the immunolocalization of the two photosynthetic enzymes were markedly different between barley and maize. In barley, the mesophyll chloroplasts had well-developed grana and their stroma was densely labeled with immunogold particles for Rubisco and for RCA. In maize, the mesophyll chloroplasts had well-developed grana but their stroma was scarcely labeled with immunogold particles, indicating a low Rubisco content. But the chloroplasts of the bundle sheath cells had only few rudimentary grana and their stroma was densely labeled with immunogold particles for Rubisco. A higher density of immunogold particles for RCA was located both in chloroplast stroma of the bundle sheath cells and the mesophyll cells. These results showed that the structure and function of chloroplasts are different between C(3) plants and C(4) plants.