0023-6152

AA00697606

23651

Unrefereed

0023-6152

AA00697606

Vascular bundles of barley leaves are surrounded by double layers, consisting of an outer parenchyma sheath and inner endodermal layers (mestom sheath). Chloroplasts exist within mestom cells as well as within parenchyma sheath cells, but the rudimentary chloroplasts within young mestom sheath cells disappear during cell differentiation. The primordia of proplastids are suggested to be different from mitochondrial primordia. In early stage of development, they have similar developmental patterns induced by invagination of their inner envelopes. Prolamellar bodies within parenchyma sheath cell etioplasts of maize leaves require light energy to be dispersed into lamellae as do those of etioplasts within mesophyll and parenchyma sheath cells of barley leaves, but those within mesophyll chloroplasts of maize leaves require more light energy. Grana are formed in barley and maize chloroplasts after 6 hours illumination. This suggests no difference in light energy requirements for formation of grana between the chloroplasts of barley and maize leaves. The ultrastructure of chloroplasts within parenchyma sheath cells of maize leaves are similar to those at early stage of chloroplast development within mesophyll and parenchyma sheath cells of barley leaves illuminated by light for 1 or 3 hours. New starch grains assimilated by photosynthesis are observed in the chloroplasts within the barley leaves after 6 hours illumination, but within maize leaves they are observed in the chloroplasts after 18 hours illumination. Etioplasts increase in size -during dark germination, but after illumination and initiation of photosynthetic activities they shrink.