Abstract: Small sections of leaves were floated on distilled water under either light or dark conditions, and were freeze-substituted in a 1 % solution of osmium tetroxide in acetone at -78°C followed by embedding in an epoxy resin. Approximately I-11m-thick sections were cut using a dry diamond knife and examined by scanning transmission electron microscopy. The relative concentrations of potassium and chloride in subcellular compartments were determined using an energy dispersive X-ray analyser. The concentration of sodium in the leaf (1·7 m-equivjkg of wet tissue) was too low to be detected by this method. The spatial resolution of this technique was sufficient to distinguish between concentrations in the chloroplasts, cytoplasm, vacuole, and nuclei. The concentration of chloride in stomata and some other epidermal cells was very much higher than in either mesophyll or bundle sheath cells. The potassium concentration in some vascular cells was at least two- to threefold higher than that in mesophyll or bundle sheath cells. The Cl : K ratio in mesophyll and bundle sheath cells resembled that in the solution (0 ·10) used for growing the plants. The concentration of chloride in the "free" cytoplasm of mesophyll cells was always very low. Significant differences were found in the "ion" relations of mesophyll and bundle sheath cells. Whereas the ratio of potassium concentration between the vacuole and chloroplasts of mesophyll cells was high (1 ·19) in the light and low (0·65) in the dark, the opposite was true for bundle sheath cells-O· 65 and 0·86 respectively. The ratio of potassium concentration between the vacuo les of mesophyll and those of bundle sheath cells was 1 ·48 in the light, but only 0·76 in the dark. These concentration gradients are discussed in relation to a possible transfer of organic acid salts of potassium between these two cell types.

Abstract: SUMMARY The effect of Endogone infection on the stem anatomy and on the reproduction in tomato, maize, strawberry and petunia was examined. In tomato, petunia and maize plants, the infection increased the amount of vascular tissue. The lignification of the xylem was greater in mycorrhizal tomato and petunia plants and more vascular bundles were produced in the maize plants. Mycorrhizal infection stimulated flower production in petunia, the formation of fruit in strawberry and the development of pollen in maize.

Abstract: Several photochemical and spectral properties of maize (Zea mays) bundle sheath and mesophyll chloroplasts are reported that provide a better understanding of the photosynthetic apparatus of C4 plants. The difference absorption spectrum at 298 K and the fluorescence excitation and emission spectra of chlorophyll at 298 K and 77 K provide new information on the different forms of chlorophyll a in bundle sheath and mesophyll chloroplasts: the former contain, relative to short wavelength chlorophyll a forms, more long wavelength chlorophyll a form (e.g. chlorophyll a 693 and chlorophyll a 705) and less chlorophyll b than the latter. The degree of polarization of chlorophyll a fluorescence is 6% in bundle sheath and 4% in mesophyll chloroplasts. This result is consistent with the presence of relatively high amounts of oriented long wavelength forms of chlorophyll a in bundle sheath compared to mesophyll chloroplasts. The relative yield of variable, with respect to constant, chorophyll a fluorescence in mesophyll chloroplasts is more than twice that in bundle sheath chloroplast. Furthermore, the relative yield of total chlorophyll a fluorescence is 40% lower in bundle sheath compared to that in mesophyll chloroplasts. This is in agreement with the presence of the higher ratio of the weakly fluorescent pigment system I to pigment system II in bundle sheath than in mesophyll chloroplast. The efficiency of energy transfer from chlorophyll b and carotenoids to chlorophyll a are calculated to be 100 and 50%, respectively, in both types of chloroplasts. Fluorescence quenching of atebrin, reflecting high energy state of chloroplasts, is 10 times higher in mesophyll chloroplasts than in bundle sheath chloroplasts during noncyclic electron flow but is equal during cyclic flow. The entire electron transport chain is shown to be present in both types of chloroplasts, as inferred from the antagonistic effect of red (650 nm) and far red (710 nm) lights on the absorbance changes at 559 nm and 553 nm, and the photoreduction of methyl viologen from H2O. (The rate of methyl viologen photoreduction in bundle sheath chloroplasts was 40% of that of mesophyll chloroplasts.)

Abstract: Photosynthetically active bundle sheath strands capable of assimilating up to 8 micromoles CO(2) per milligram chlorophyll per hour have been isolated from fully expanded leaves of Zea mays L. Mesophyll cell contamination of the preparations was negligible, as evidenced by light and electron microscopy and by a high ratio of chlorophyll a to chlorophyll b in the strands. Ribose 5-phosphate markedly stimulated the rate of photosynthetic (14)CO(2) fixation by the isolated strands. In contrast, both pyruvate and phosphoenolpyruvate had a comparatively small stimulatory effect on bundle sheath (14)CO(2) fixation. After 5 minutes of photosynthesis in (14)C-bicarbonate, 95% of the incorporated (14)C was found in compounds other than C(4)-dicarboxylic acids, most notably in 3-phosphoglycerate and sugar phosphates. A similar distribution of (14)C was observed in the presence of exogenous ribose 5-phosphate. Extracts of bundle sheath strands contained high specific activities of "malic" enzyme, phosphoglycolate phosphatase, hydroxypyruvate reductase, and ribulose 1,5-diphosphate carboxylase, whereas the specific activities of NADP(+)-malate dehydrogenase and phosphopyruvate carboxylase were extremely low. These results indicate that the Calvin cycle occurs in the bundle sheath cells of maize.

Abstract: The feeding sites of four species of psyllids were compared histologically. Cardiaspina albitextura, Creiis costatus and Lasiopsylla rotundipennis draw their food from cells of the sheathing parenchyma and pholem tissue of small vascular bundles. Glycaspis sp. feeds from the pholem cells of much larger bundles. Obvious damage to leaf tissue was associated only with C. albitextura and Glycaspis sp., and was much more severe for the former. The damaged tissue resembled that of naturally-senescing leaves. This suggests that these two species are able to augment the food available from vascular bundles by causing a breakdown of palisade mesophyll.

Abstract: Protease formation in Phaseolus vulgaris L. cotyledons during seed germination was studied histochemically using a gelatin-film-substrate method. Protease activity can be detected by this method on the 5th day of germination, at approximately the same time that a rapid increase of activity was observed by a test-tube assay with casein as a substrate. At the early stage of germination, protease activity was observed throughout the cotyledon except in two or three cell layers below the cotyledon surface and in several cell layers around the vascular bundles. A highly active cell layer surrounding the protease-inactive cells near the vascular bundles is suggested to be a source of the protease.

Abstract: Mitotic activity does not stop for different meristematic cells of the root apex at the same distance from the initials. The differences are connected with the functional heterogeneity of the apical meristem of the root. The arrangement of vascular bundles,i.e. the alternation of independent xylem and phloem groups, is of major importance. In broad bean roots, the protophloem sieve elements stop dividing first. The centre of the stelei. e. late metaxylem elements stop dividing next. Division in the stele gradually ceases centrifugally, while it ceases centripetally in the peripheral part of the root. The cylindrical region with prolonged cell division includes internal layers of the cortex including endodermis, pericycle and adjoining cells of the stele. Proximally apical meristem is reduced to isolated strands of cells adjacent to the protoxylem poles. Pericycle cells stop dividing last at a distance of approx. 9–10 mm from the initials.

Abstract: Three pathways of net carbon assimilation and reduction have been detected in certain higher plant The three recognized pathways are: the reductive pentose phosphate, the C4-dicarboxylic, and crassulacean acid metabolism Leaves of a given plant may exhibit at least one of these pathways A plant exhibiting a particular one of these carbon pathways also will possess a distinctive leaf morphology Plants with crassulacean acid metabolism will have fleshy leaves In a light or electron microscope, the vascular bundle sheath cells of neither crassulacean nor pentose types of leaves will exhibit extensive development of organelles such as chloroplasts, mitochondria, ro peroxisomes Plants using the C4-dicarboxylic pathway will exhibit, in light and electron microscopy, a dense concentration of these organelles in leaf bundle sheath cells Thus leaf cell morphology, plus organelle distribution and biochemistry, are intimately related in a very specific manner such that photosynthesis in a given plant proceeds

Abstract: Lipid compositions of undifferentiated maize (Zea mays) chloroplasts, capable of fixing CO2, were compared with the lipid compositions of mature chloroplasts, which do not fix CO2, located in both the mesophyll and bundle sheath cells. The major lipids found in all three chloroplast types were the glycolipids, monogalactosyl diglyceride and digalactosyl diglyceride, followed by decreasing amounts of sulfolipid, phosphatidyl glycerol, phosphatidyl choline, phosphatidyl inositol, and diphosphatidyl glycerol. Quantitative differences in lipid components were observed among the chloroplast types. The mesophyll and bundle sheath maize chloroplasts differed in their chlorophyll a/chlorophyll b ratios (2.27 and 4.13 respectively) and their content of glycolipid relative to chlorophyll (51.8% glycolipid to 20.9% chlorophyll and 84.5% glycolipid to 10.1% chlorophyll respectively). A comparison between the lipid compositions of maize mesophyll chloroplasts and mesophyll chloroplasts obtained from spinach, sugar beet, and tobacco showed many similarities.

Abstract: Transverse sections of receptacle and capsule of Papaver somniferum in acropetal succession reveal the distribution and branching of vascular bundles to the sepals, petals, and stamens. Eventually three or four of these vascular bundles fuse to form 11 amphicribral bundles which supply the base of the capsule. In the process of fusion, the xylem assumes a reniform shape in transverse section. In each bundle the phloem extends around one side of the xylary strand. Two adjacent vascular bundles with their xylary strands facing each other join. Xylem joins xylem, and phloem becomes continuous around the resulting xylem strand to form an amphicribral bundle. Ascending toward the distal end of the capsule, these bundles bend and become progressively reduced from an amphicribral to a collateral type of vascular bundle.

Abstract: An increasing sugar gradient in the rib, a decreasing gradient in the upper region of the petiole, and a sharp increase in the base of the petiole were found when transverse segments of the rib and petiole of a sugar beet leaf or the isolated vascular bundles as a whole were analyzed. The sugar concentration and the gradient pattern varied considerably with the leaf position in the ontogenic sequence. The proportion of assimilated 14C exported as sucrose was highest for leaves of intermediate age, which were at the nearly mature stage. Mature and old leaves exported less 14C and young leaves, which had a high sugar concentration in the blade and a sharply decreasing gradient in the petiole, exported very little. Analysis of vascular bundles in the petiole which serve the tip and basal regions of the blade after 14CO2 incorporation into the blade indicated that a much larger amount of 14C-sucrose entered into and moved through the basal bundle than into and through the tip bundle.

Abstract: Bacilliform particles were found in thin sections of leaves from raspberry (Rubus idaeus L.) infected with raspberry vein chlorosis virus. Similar particles were not found in leaf tissue from a healthy raspberry plant or from a plant infected with raspberry mosaic virus. The bacilliform particles were detected in parenchyma cells within the vascular bundle or mesophyll cells near the vascular bundle. The particles were restricted to the cytoplasm and occurred singly or in bundles of from 2 to 14 parallel particles enclosed within a vesicle. particles were rounded at both ends. the mean dimensions of 42 particles were 506 × 83 nm (ranges: 442 to 560 nm and 73 to 91 nm). in cross section, the particles had three concentric layers, with average diameters of 83 nm, 53 nm, and 23 nm. the wall of each layer was about 70 A thick and the middle layer showed regular surface striations with a periodicity of 50–55 A.

Abstract: The examination of the morphological structure of a cross section in the leaf of Panicum maximum showed that the vascular bundles are encircled by a layer of specialised cells: the bundle-sheath parenchyma cells. A dimorphism in the chloroplasts was also put in evidence, which is related to the metabolism of the atmospheric carbon fixation. The bundle-sheath contains a morphologically distinct type of chloroplasts: they are large (0,009-0,011 mm) and have the possibility to accumulate starch : during a sunny day, the storage can be 40 % of the initial dry weight of the leaf...

Abstract: In the previous paper, a hypothesis (Model N), interpreting the morphological nature of the normal spikelet in rice plant, was proposed. And it was postulated that the main vascular bundle in the axis of the normal spikelet consists of two kinds; that of spikelet axis (rachilla) and that of floret one, and their connective point presents in the axis between upper empty glume and palea. In this paper, the course of vascular bundle of the normal spikelet is traced with serial-microtome sections. The main vascular bundle extends to lateral direction in the level just above the abcission layer (Plate 1-1∼3) and forms a ring (Plate 2-1), that is, a vascular cylinder. As shown in Plate 1, it is clear at higher level that the main vascular bundle has a large gap (arrow symbols in Plate 1) between the both bases of midrib trace of lemma and palea (a and o in Plate 1). And the main vascular bundle forms a solid column from the gap to the base of pistil. To research the detail of the vascular course around the gap is an important problem. The trace of midrib of lemma (a in Plate 2-2) detaches itself from the vascular cylinder at the ventral side, forming an incomplete gap on this cylinder (Plate 2-1∼3). The half tissue of the vascular cylinder containing left and right parts of the leaf trace "a", increases in the thickness at the ventral side and two lateral leaf traces diverge into the latero-ventral position from the both parts (b and c in Plate 2-3). These traces connect with each lateral veins of lemma. Subsequently the both parts of the vascular cylinder join together inside of the cylinder and synchronously detach themselves from the dorsal arc of the cylinder (Plate 2-4∼5). In this way, the main vascular bundle of solid column type is composed at the ventral side, namely at the axil of lemma (vfa in Plate 2-6, 7). And this main vascular bundle diverges the traces into the flower organs; palea, lodicules, stamens and pistil (see Plate 1). However, it does not always occur in palea as follows. The dorsal arc of the vascular cylinder divides into four fragments after the divergence of a trace (c2 in Plate 2-5, 7), forming a gap, into upper empty glume. Two fragments of outer side (m and n) supply a trace to each marginal veins of lemma. Two remnants (w and z) join again each other as shown in Plate 2-8, and connect with the midrib of palea (o in Plate 2-11). Therefore, the midrib of palea, not producing any gaps, is classified into two kinds according to its origin (one; "o" in Plate 1, the other; "o" in Plate 2). The main vascular connection between "cylinder" and "solid column" is observed at the nordal region, where axillary axis (floret axis) branches out from main axis (spikelet axis), as shown in other grass spikelets, for example, Triticum and Bromus. The vascular system between the main vascular bundle of solid column type and traces of the flower organs resembles to that of floret in other grass spikelets, except that the traces of palea does not always diverges from the main vascular bundle of solid column type. Moreover it seems that these vascular courses in the normal spikelet are quite alike an unilacunar type as usually seen in many dicots. The conclusion obtained from these comparative anatomical aspects is that the main vascular bundle of solid column type at axil of lemma is considered to be a branch trace in connection with the vascular cylinder. In other words, the vascular cylinder and its branch trace are correspond to the main vascular bundle of spikelet axis and that of floret one, respectively. It can be said that our conclusion does not contradict with the hypothesis (Matuba, 1971) shown previously. Such anatomical analysis leads us to a conclusion that the axis in the normal spikelet consists of two kinds; spikelet axis and floret one, in spite of the external appearance as same as single axis. [the rest omitted]

Abstract: (1) In order to elucidate the mechanism of gall formation caused by the root-knot nematode, an egg mass of Meloidogyne incognita var. acrita was inoculated on the second internode of balsam plant (Impatiens balsamina L.), and investigation of the process of gall formation and histological studies of galled stem tissue were made during 8 weeks after inoculation.(2) The gall swelling could be distinguished externally 2 weeks after inoculation. The tissue thickness on the inoculated side increased gradually after inoculation, in particular, it increased markedly between 4 and 8 weeks after inoculation.(3) Among the histological observations, the first reactions of plant tissue infected with nematodes were cell enlargement and cell division in the pith, vascular bundle and cortex. Increases in the pith and cortex thickness resulted from cell division. However, in the cortex, cell division was followed by cell enlargement 7 weeks after inoculation. An increase in the area of vascular bundle tissue resulted from both cell division and cell enlargement.(4) The length of life cycle in this nematode was about 4 weeks under the experimental conditions.

Abstract: SummaryThe ‘tuber stalks’ of sweet potato tubers from a local cultivar (A 28/7) were found to develop extensive secondary phloem and phloic vascular bundles which have not been previously described. The bundles were formed in the secondary phloem parenchyma during the later stages of tuber development and in larger tubers extended from the endodermis to the stele, but they also arose within the cortex in some roots. They presumably play a significant role in the transport of assimilates to tubers in intact plants and apparently enable tuber growth to continue despite damage to the stalk caused by larvae of the Pyralid moth Megastes grandalis.

Abstract: A B S T R A C T Anomalous secondary thickening occurs in the main axis of Bougainvillea spectabilis as a result of a primary thickening meristem which differentiates in pericycle. The primary thickening meristem first appears in the base of the primary root about 6 days after germination and differentiates acropetally as the root elongates. It begins differentiating from the base of the hypocotyl toward the shoot apex about 33 days after germination. The primary thickening meristem is first observable at the base of the first internode about 60 days after germination. It then becomes a cylinder in the main axis of the seedling. No stelar cambial cylinder forms in the primary root, hypocotyl, or stem because vascular cambium differentiation occurs neither in the pericycle opposite xylem points in the primary root nor in interfascicular parenchyma in the hypocotyl or stem. The primary vascular system of the stem appears anomalous because an inner and an outer ring of vascular bundles differentiate in the stele. Bundles of the inner ring anastomose in internodes, whereas those of the outer ring do not. Desmogen strands each of which is composed of phloem, xylem with both tracheids and vessels, and a desmogic cambium, differentiate from prodesmogen strands in conjunctive tissue. The parenchymatous cells surrounding desmogen strands then differentiate into elongated simple-pitted fibers and thick-walled fusiform cells that are about the same length as the primary thickening meristem initials.

Abstract: The species Arundinella hirta L. posseses a striking variation of the leaf anatomy that is characteristic of C(4) grasses. In addition to a sheath of large, bright green cells around the vascular bundles, there are strands of large parenchyma cells which appear identical to the bundle sheath cells and which run parallel to the vascular bundles, but which are not associated with any vascular tissue. This species may be useful for studying the cellular compartmentalization associated with the C(4) pathway and should provide interesting material for determining the role of translocation in the functioning of the C(4) system.