Ultrastructural Observations in the Suppression of Granal Development in Bundle Sheath Chloroplasts of NADP-ME Type C4 Monocot and Dicot Species.

We examined chloroplast development with respect to the stacking of grana in Zea mays L., an NADP-ME type C4 monocot, and in Portulaca grandiflora, an NADP-ME type C4 dicot species. In both species, mean numbers of thylakoids per granum in bundle sheath chloroplasts were suppressed less than 3 throughout chloroplast development while they were increased gradually in mesophyll chloroplasts. It was concluded that in both phylogenetically distinct NADP-ME type C4 plants the stacking of grana was suppressed in bundle sheath chloroplasts from early developmental stages.