Amount Of Starch Grains Research Articles

Embryology and taxonomical position of Retzia capensis (Retziaceae)

The ovules of Retzia capensis are anatropous, unitegmic and tenuinucellate. A well‐developed hypostase of concentric layers of cells is present. Embryo sac formation follows Polygonum type. The central part of the mature embryo sac contains rich amounts of starch grains, which disappear at the beginning of the endosperm development. The endosperm formation results in a chalazal haustorium of a great number of long, narrow, densely plasmatic cells, a micropylar haustorium of loosely plasmatic cells, and a middle region which in the beginning is only partly cellular, but later the whole endosperm consists of long, narrow cells. The hypostase prevents the chalazal endosperm haustorium from penetrating to the lower part of the ovule, while the micropylar haustorium is able to grow upwards into the long micropyle. The cellular endosperm formation, the formation of endosperm haustoria, of which the micropylar is most distinctive, and formation of a well‐developed hypostase all indicate a close relationship to Buddleiaceae and part of Scrophulariaceae. Therefore, both Retziaceae and Buddleiaceae should be placed in the order Scrophulariales.

The effect of light intensity on ultrastructure of chloroplasts in konjak (Amorphophallus konjac K. Koch).

Konjak plants were given treatments of full sunlight, 50% and 70% shading immediately after leaflet expansion. Ultrastructure of the chloroplasts in leaflets at the top and base of blades was examined with an electron microscope at intervals of one or two weeks after treatment. 1. Leaf area increased at all light intensities for two weeks after leaflet expansion and the largest area was obtained from the plants grown at 70% shading. Green area of leaves grown at full sunlight began to decrease from 40 days after the leaflet expansion, but the leaves grown under the shade maintained the fully expanded area for three months (Fig. 1). 2. The chloroplasts just before the treatment had rudimentary grana, a small amount of plastoglobules and starch grains (Figs. 2 and 3), but two weeks after treatment the ultrastructural differences were noted in the chloroplasts developed at different light intensities. 3. The chloroplasts from plants grown at full sunlight had poorly organized grana consisting of 2-5 overlapping thylakoids, which began to separate from two weeks after leaflet expansion (Fig. 4). Most of the chloroplasts in adaxial side of palisade cells showed swelling and the grana had been destroyed at four weeks after leaflet expansion (Fig. 5), whereas those in abaxial side of palisade cells and in spongy parenchyma cells remained without conspicuous destruction (Figs. 7 and 8). In the chloroplasts from plants grown at full sunlight, the starch grains decreased but the plastoglobules continued to increase with aging (Figs. 4 and 5). 4. The chloroplasts from plants grown at both 50% and 70% shading contained well-developed grana having more than 10 overlapping thylakoids, which remained without remarkable separation for three months after leaflet expansion (Figs. 9-12). The difference was not clear in development of the inner membrane system between the chloroplasts from plants grown at 50% and 70% shading, but the chloroplasts from 50% shading contained larger amount of starch grains than those from 70% shading (Figs. 9-12). The change in chloroplast structure by shading was more distinct in leaflets at the top of blade than in those at the base (Figs. 4 and 13). According to the observation of the chloroplasts in konjak, which has been characterised as a shade plant, it is considered that the development of grana is accelerated under low light intensity and the senescence of chloroplast is delayed.

The Effect of Seeding Density, Temperature and Light Intensity on Ultrastructure of the Chloroplasts in Rice Seedlings

In the first experiment, ultrastructure of the chloroplasts was observed by an electron microscope from rice seedlings grown in controlled nursery environments under combinations of seeding density and temperature. Large amounts of starch grains were accumulated in chloroplasts of the uppermost fully expanded leaves grown under the combination of lower seeding density (9 cm2/seed) and lower temperature (25.1°C day max./11.3°C night min.), while the chloroplasts from the combination of higher seeding density (2 cm2/seed) and higher temperature (29.5°C day max./11.3°C night min.) had smaller starch grains. Chloroplasts from leaves grown under the lower seeding density and lower temperature had well-formed grana consisting of more number of overlapping thylakoids than those from the higher seeding density and higher temperature. In the second experiment, the effects of temperature and light intensity were studied on accumulation of starch grains and on formation of grana in chloroplasts of the uppermost fully expanded leaves. At the lower temperature (21.7°C day max./11.5°C night min.), increased amounts of starch grains were accumulated in the chloroplasts, but the grana were little affected by the lower temperature. Chloroplasts from leaves grown under the lower light intensity (60% shade in glasshouse) had many rudimentary grana consisting of 2-4 overlapping thylakoids. Consequently, the total number of grana thylakoids per chloroplast section was markedly reduced at the lower light intensity.

Histochemical Studies of Ovary Tissues During the Embryo Sac Development inPaspalum LongifoliumRoxb.

SUMMARYIn this study, changes in the distribution of polysaccharides and lipids and stainability of ABB and AB during the embryo sac development in the tetraploid and octoploid of Paspalum longifolium were examined in the glutaraldehyde-fixed, Epon-embedded ovary sections. Starch grains and lipid granules accumulate most abundantly in the ovary wall. They also accumulate in a considerable amount in the embryo sac. The stainability of ABB in different tissue cells are parallel to that of AB except that of the nuclear saps in the nuclei of the embryo sac. Deoxyribonucleic acid in the nuclei of the developing and mature embryo sac, except those of mature antipodals, are hardly stainable with AB and Feulgen reagent. Antipodals may be metabolically very active in transporting nutrients into the embryo sac through the intimate connection between these cells and the nucellus and papillae on the inner surface of antipodal wall adjacent to nucellar cells. They also contain a large amount of starch grains and lipids in liquid state. Both the central cell and egg are higly vacuolated and contain a considerable amount of starch grains and lipid droplets. Filiform apparatus of the two synergids develops from the micropylar wall between these two cells as well as from the micropylar wall adjacent to the region believed to be the degenerated megaspore (s) and is composed mainly of polysaccharides. These polysaccharides seem to have been transformed from starch grains stored in the synergids at an early stage. The cytoplasm around each filiform apparatus stains rather intensely with ABB and AB. Many lipid granules are also present around this apparatus. The nucellar cells below the embryo sac, micropylar integumentary cells, cells in the ovule attachment region (OAR), and cells of the cell strand connecting the OAR and ovary base are all much less vacuolated and rich in cytoplasm. They form a connection from the base of the ovary to the micropylar end of the embryo sac, probably for the translocation of nutrients into the embryo sac. No significant difference in the distribution and concentration of polysaccharides and lipids during embryo sac development in the ovaries of the tetraploid and octoploid was observed, except starch grains and lipid granules, both of which are larger and more numerous in the latter than in the former.

ミトリササゲの発芽初期における澱粉粒の消長

1. Changes in the distribution and the amount of starch grains were observed following the development of various organs and tissues in young seedlings of a bean, Vigna sesquipedalis.2. The amount of starch grains in the cotyledon decreases steadily as germination proceeds; after 24hr. the decrease is especially abrupt. Starch grains are first consumed in the outer portion of the cotyledon and the consumption proceeds then inward, and finally, on the 7th day, starch grains are observable only in the cells around the vascular bundles.3. In the presumptive abscission region of the cotyledon, there is a marked accumulation of starch grains from the 2nd to the 5th day; on the 5th day the inception of a histologically detectable differentiation of abscission layer of the cotyledon appears.4. The hypocotyl and the epicotyl possess a definite amount of starch grains at the beginning of germination; from 25 to 30hr. the amount of starch grains becomes minimum; soon after they increase again and on the 2nd day their amount reaches maximum; then they decrease gradually until the starch grains are almost all consumed on the 6th day, except for a few remaining in the starch sheath of the hypocotyl.5. In the radicle, there is a heavy accumulation of starch grains in the root cap cells and markedly so in the starch sheath of the elongation zone, reaching a maximum on the 2nd day.6. In the plumule, starch grains are first detectable only in the dorsal part adjacent to the midrib; on the 2nd day they locate throughout the dorsal mesophyll tissue and then they decrease gradually until on the 6th or 7th day a few starch grains are retained only in the cells beneath the midrib.