Abstract
The lamina joint (LJ) and pulvinus of grasses are slightly pale green as compared with the leaf blade, leaf sheath, and stem. In Arundinella hirta, the blade, sheath and stem show Kranz anatomy and the C4 pattern expression of photosynthetic enzymes. We investigated the cell structure and photosynthetic enzyme expression in the LJ and pulvinus. These tissues substantially lacked stomata and Kranz anatomy, but the parenchyma cells included a few granal chloroplasts. The chloroplasts of pulvinus contained large starch grains. Western blots demonstrated that the LJ and pulvinus also accumulate PEPC, NADP-ME, Rubisco, and PPDK, but the NADP-ME differed in the molecular weight from NADP-ME of the blade, sheath, and stem. Immunogold electron microscopy revealed that high-level expression of Rubisco and low-level expression of PEPC and PPDK occur within the same cell. These data suggest that a single-cell-type C4-like metabolism may operate in the LJ and pulvinus.
