Abstract: The photochemical activities of chloroplasts isolated from bundle sheath and mesophyll cells of maize (Zea mays var. DS606A) have been measured. Bundle sheath chloroplasts are almost devoid of grana, except in very young leaves, while mesophyll chloroplasts contain grana at all stages of leaf development.Chloroplast fragments isolated from bundle sheath cells showed a light-dependent reduction of potassium ferricyanide, 2, 6-dichlorophenolindophenol, mammalian cytochrome c, plastocyanin, and Euglena cytochrome c(552). These activities were inhibited by 3-(3, 4-dichlorophenyl)-1, 1-dimethylurea at 1.25 micromolar. However, the photoreduction of NADP from water was extremely low or absent, except in chloroplasts from very young leaves, and the capacity for NADP reduction appeared to be related to the degree of grana formation.Photosystem I activity was present in bundle sheath chloroplast preparations at all stages of leaf growth and senescence examined. However, the activity was lower than in isolated mesophyll chloroplasts. NADPH diaphorase activity was comparable in both types of chloroplast.Chloroplasts isolated from bundle sheath cells of plants grown under a variety of conditions, including continuous and intermittent light, high and low light intensities, and high temperature, exhibited photosystem II activity.

Abstract: A seven-step sequential grinding procedure was applied to leaves of Atriplex rosea, Sorghum sudanense, and Spinacia oleracea to study the distribution of carboxylases and microbody enzymes. In the extracts from C4 species there were 7- to 10-fold reciprocal changes in specific activities of ribulose-1, 5-diphosphate carboxylase and phosphoenolpyruvate carboxylase. No such changes occurred in sequential extracts from spinach. No inhibitors of ribulose-1, 5-diphosphate carboxylase were detected when the mesophyll extracts of Sorghum were assayed together with spinach extracts. These results reaffirm the conclusion of others that phosphoenolpyruvate carboxylase is largely confined to the mesophyll in these species and ribulose-1, 5-diphosphate carboxylase to the bundle sheath. The specific activities of glycolate oxidase and hydroxypyruvate reductase in bundle sheath extracts were two to three times those in mesophyll fractions. Catalase behaved similarly in Atriplex rosea but in Sorghum the specific activity was virtually the same in all fractions. From the relative amounts of these enzymes present, and comparison with the data obtained from spinach, it is concluded that typical leaf peroxisomes are present in the bundle sheaths of both C4 species and in the mesophyll of Atriplex rosea. The relative enzyme activities in the mesophyll of Sorghum suggest that the microbodies there are of the non-specialized type found in many nongreen tissues. The activities of the microbody enzymes in the bundle sheath of Sorghum seem quite inadequate to support photorespiration.

Abstract: The complex foliar nectaries of Pithecellobium macradenium Pittier represent one of the more highly specialized types of nectaries found in the Leguminosae. The vascular bundles that supply the nectaries are branches from adaxial bundles of a complex petiole or leaf-rachis supply. Small cupular glands occur on the rachides of the leaves, and each gland has a branched vascular supply with a discontinuous ring of supporting sclerenchyma. A large functional petiolar nectary is present, with its vasculature consisting of bifurcating veins that form an interrupted cylinder. A continuous ring of supporting sclerenchyma is peripheral to the vascular tissue. The secretory tissue of the nectaries is supplied by both phloem and xylem.

Abstract: The structural pattems of the primary vascular systems in some species of Leguminosae and Rosaceae have been determined by tracing the longitudinal course of the vascular bundles in terminal stem segments. These systems are interpreted as consisting of sympodia. Each sympodium is composed of an axial bundle which is continuous through the length of the segment and from which arise trace bundles that supply leaves and axillary buds. A compact arrangement of vascular bundles seems to correlate with the woody habit. Regardless of the degree of compactness of the primary vascular system, the structural identity of the individual sympodia is maintained. The total number of vascular bundles at a particular level is related to the number of axial bundles in the system, the number of traces per leaf and per axillary bud, and the number of internodes traversed by the traces prior to entering a lateral appendage. Shrubs and trees have more vascular bundles than herbs. Data from this study and the literature indicate that the vascular system is predominantly of the open type in dicotyledonous plants which have helically arranged leaves and, further, that in such plants with a 3-trace, trilacunar nodal structure, the number of sympodia coincides with the number of orthostichies (which is also the denominator of the phyllotactic fraction). In open systems leaf gaps cannot be morphologically delimited. Because of the resemblance of the open type of angiosperm vascular system to that of certain gymnosperms, previously interpreted to have evolved from a protostele, we suggest that the eustele of angiosperms is homologous with the stele of gymnosperms. We believe, also, that angiosperms, like gymnosperms, are probably not characterized by leaf gaps of filicinean type. We provide, furthermore, a rationale for the view that the axial bundle of a sympodium is a cauline structure.

Abstract: Enzyme changes in root initials of Hydrangea macrophylla during adventitious root formation are described. Extensive changes in enzyme activity were demonstrated by histochemical staining and all enzymes investigated showed increased activity in the tissue responsible for root initiation.The earliest change observed was that of peroxidase in the phloem and xylem ray cells. This was followed by a change in the activity of cytochrome oxidase and succinic dehydrogenase. Alpha-amylase was localized by the substrate film method. The highest amylase activity was demonstrated in the epidermal tissues and vascular bundles. As the root primordia developed, enzyme activity shifted from the vascular bundles to the periphery of the bundles. A positive correlation was found between the starch content and root number of cuttings.

Abstract: HIGH rates of photosynthesis and low rates of photorespiration are found in several plant species in which the photosynthetic carbon reduction (PCR) cycle is augmented by a second carboxylation system, the C-4 pathway1,2. This pathway does not result in a net fixation or reduction of carbon, but seems to operate as a mechanism for concentrating CO2 at the site of reductive assimilation. It has been widely accepted that the carboxylation reaction of the C-4 pathway is associated with the chloroplasts of mesophyll -cells, while PCR cycle activity is restricted to the bundle sheath chloroplasts. Investigations3–5 indicate, however that mesophyll chloroplasts do contain PCR cycle activity, arni that the C-4 pathway is located in the cytoplasm of non-green and mesophyll cells.

Abstract: The development of peripheral reticulum (PR) in chloroplasts varies in C3 and C4 plants. In general, PR is more extensive in C4 plants, but PR is also seen in the chloroplasts of some C3 plants. Within some C4 plants, PR is seen in the bundle sheath cells which predominantly use the C3 pathway. Thus, PR is not associated directly with the presence of the C4 pathway on a cellular basis. Its predominance in C4 plants must be related to some characteristic other than the method of CO2 fixation. Ultrastructural evidence suggests that PR is associated with the rapid transfer of substances into and out of chloroplasts and from mesophyll to bundle sheath cells.

Abstract: Leaves of plants possessing the C4-dicarboxylic acid CO2fixation pathway (14) are characterized by outer mesophyll cells containing granal chloroplasts and inner bundle sheath cells which contain chloroplasts with varying degrees of grana development depending on the species. As judged by Hill activities and fluorescence yield, bundle sheath chloroplasts which contain few grana have less photosystem II activity relative to photosystem I when compared to mesophyll cell chloroplasts in the same leaf (5, 11, 13, 15, 16). The deficiency in PS-II' in these bundle sheath chloroplasts is further shown by the low chl/P700 ratio in bundle sheath chloroplasts of Sorghum bicolor and Digitaria sanguinalis (1, 13) and by the near absence of pigment-protein complex II (associated with PS-II) in bundle sheath chloroplasts of S. bicolor (12). These studies show that bundle sheath chloroplasts of C4 plants which contain few grana are highly deficient in PS-II and closely resemble the PS-I particles prepared from spinach chloroplasts by digitonin treatment (1). The major deficiency in PS-II activity reported for S. bicolor bundle sheath chloroplasts, for example, has important consequences for Calvin cycle metabolism which occurs in the bundle sheath cells of this species. All carbon fixed during photosynthesis eventually passes through the Calvin cycle in the bundle sheath cells and, in view of major deficiency in PS-II, it has been suggested that NADPH is provided via malic enzyme (10, 14) and that ATP is generated via cyclic photophosphorylation (6, 14). There have been relatively few studies of photophosphorylation in chloroplasts of C4 plants (6, 8), and in these no distinction was made between mesophyll and bundle sheath origin. This paper reports studies on photophosphorylation as a measure of coupled electron flow in chloroplasts from three C4 species, S. bicolor, Zea mays and Atriplex spongiosa. The data demonstrate a major deficiency of PS-II dependent photophosphorylation in fragments obtained from bundle sheath cell chloroplasts of S. bicolor and Z. mays.

Abstract: Laterally connected vascular bundles in the nodes of sugarcane (Saccharum species cv. Pindar) stalks allow a rapid redistribution of water across the stalk should the vascular continuity be partly disrupted. Tritiated water supplied to the roots exchanged rapidly between the xylem and storage tissue so that net movement up the stalk was slow. The half-time for exchange in a labeled stalk was about 4 hours so that the entire water content of a sugarcane stalk can turn over at least once in a single day. No rapid flux of sugar between xylem and phloem or xylem and storage tissue was detected. Functional xylem contained only low sugar concentrations: less than 0.3% w/v in the stalk and less than 0.02% w/v in the leaf. Previous reports of high sugar levels (9% w/v) in sugarcane stalk xylem reflect some degree of xylem blockage followed by a slow equilibration with free space sugars in the storage tissue.

Abstract: Photoreduction of NADP from water in agranal chloroplasts isolated from the leaf bundle sheath cells of Zea mays (var. DS 606A) or Sorghum bicolor (var. Texas 610) was dependent upon addition of plastocyanin as well as ferredoxin. Activity was further increased by the addition of ferredoxin NADP-reductase. Saturation for plastocyanin was reached at about 6 micromolar. In contrast, grana-containing chloroplasts isolated from leaf mesophyll cells of these plants or from pea (Pisum sativum L.) leaves did not require either plastocyanin or ferredoxin NADP-reductase for NADP photoreduction from water, although with some preparations plastocyanin stimulated the activity.Photosystem I activity, which was low in washed preparations of bundle sheath chloroplasts, was also stimulated by plastocyanin. The effect of plastocyanin on photosystem I activity in the grana-containing chloroplasts was similar to that on NADP photoreduction from water.In the presence of plastocyanin, the rates of NADP photoreduction from water were about the same in the agranal and granal chloroplasts, but photosystem I activity was considerably higher in bundle sheath chloroplasts. In these chloroplasts photosystem II appeared to limit the rate of NADP photoreduction.The results indicated that the agranal bundle sheath chloroplasts reduced plastocyanin via photosystem II and oxidized it via photosystem I. Both types of maize chloroplast photoreduced oxidized plastocyanin, but in the presence of methyl viologen, reduced plastocyanin was photo-oxidized only by the bundle sheath chloroplasts.

Abstract: After illumination intact leaves of Zea mays contain sucrose and starch The latter is located mainly in the bundle sheath cells When 05 mm wide leaf strips are incubated with sucrose solution, the starch deposit in the bundle-sheath chloroplasts is greatly increased by light When isolated bundle sheath cells are suspended in water or solutions of sucrose and various metabolites they are not capable of synthesizing starch An appreciable production of starch in the chloroplasts of isolated bundle sheath cells can be observed only in the presence of glucose-1-phosphate

Abstract: A B S T R A C T The robust emergent leaves of Sparganium eurycarpum and S. americanum are supported by corner fiber masses and large bundle sheaths, but the thin floating leaves of S. fluctuans and S. minimum have only moderate bundle sheaths. In emergent types heavily photosynthetic diaphragms bearing vascular bundles are separated from each other in the leaf compartments by three lightly photosynthetic diaphragms without bundles, but in floating types only every other heavily photosynthetic diaphragm has a bundle. Palisade chlorenchyma occurs only at aerial surfaces-abaxial and adaxial in emergent leaves, but only adaxial in floating leaves. Extra photosynthetic areas are provided in emergent leaves by concentrations of chlorenchyma in limited areas on interior partitioning walls, while the remainder of the walls is translucent. Since only 25 % of the diaphragms are heavily photosynthetic, and the others essentially transparent because of their diffusely distributed chloroplasts and large intercellular spaces, a sieve effect exists which allows even the interior parts of thick emergent

Abstract: The photo-oxidation of cytochrome f (cytochrome c(554)) in bundle sheath cells isolated from leaves of maize (Zea mays var. DS 606A) has been compared with that in intact maize leaf and in isolated pea leaf cells (Pisum sativum L.). In all cases, illumination with red light caused a negative absorbance change at 554 nm which was attributed to the oxidation of cytochrome f. The extent of this change was greater using monochromatic red light at wavelengths above 700 nm compared with wavelengths below 700 nm. 3-(3,4-Dichlorophenyl)-1, 1-dimethylurea abolished this difference in bundle sheath cells. After illumination for 1 minute or longer in bundle sheath cells, reduction of cytochrome f in the dark was rapid only if the wavelength of the illuminating light was below 700 nm. In the presence of 3-(3,4-dichlorophenyl)-1, 1-dimethlyurea, reduction was slow after illumination at all wavelengths.Cytochrome f photo-oxidation was also followed in cells of a mutant of Chlamydomonas reinhardi, ac-21, which has isolated chloroplasts that exhibit photochemical reactions similar to those shown by isolated bundle sheath chloroplasts. No evidence was obtained for photoreduction of cytochrome f in the mutant.It was concluded that in the chloroplast of the intact bundle sheath cell of maize there is electron flow between photosystem II and cytochrome f resulting in photoreduction of the cytochrome.

Abstract: The pH dependence of the photoreduction of ferricyanide and the photoreduction of NADP from water and photosystem I activity have been compared in isolated chloroplasts from mesophyll and bundle sheath cells of Zea mays. The maximum activity of photoreduction of ferricyanide occurs at pH 8.5 in isolated mesophyll chloroplasts. The addition of methylamine does not cause a marked shift in the pH maximum, but brief sonication lowers the pH maximum to 7.0. In contrast, isolated bundle sheath chloroplasts have a pH maximum at 7.0 and the shape of the pH versus activity curve is similar to that of sonicated mesophyll chloroplasts. When photoreduction of ferricyanide by the isolated chloroplasts is measured at their pH maxima, the values for bundle sheath chloroplasts are about half those of methylamine-treated mesophyll chloroplasts on a chlorophyll basis. The pH maxima for the photoreduction of NADP from water and photosystem I activity are similar in both mesophyll and bundle sheath chloroplasts with maximum activity occurring at pH 7.0 in both cases. In the presence of added plastocyanin and ferredoxin NADP-reductase, the photosystem I activities of both sonicated mesophyll and sonicated bundle sheath chloroplasts are significantly higher than those of the unsonicated preparations. On a chlorophyll basis, photosystem I activity of bundle sheath chloroplasts is at least twice that of mesophyll chloroplasts.

Abstract: The structure of the vascular bundles in the vegetative nodes of rice has been studied in serial transverse sections. Three types of bundles are present in the vegetative nodes: (1) elliptical bundles containing numerous xylem transfer cells; (2) diffuse bundles; (3) tiny anastomosing bundles. The latter two types of bundles do not contain any xylem transfer cells. In the vegetative nodes of rice, phloem transfer cells do not occur and nodal plate bundles are absent. The significance of the distribution of the vascular tissue and the transfer cells in the rice node is discussed in particular reference to that reported earlier for wheat.

Abstract: There are various ambiguities in the interpretations of the male floret and inflorescence in the Myricaceae. Myrica esculenta Buch -Ham var farquhariana (Wall) Chev, as a relatively primitive species in the family, was chosen for detailed study The presence of tertiary bracts in one individual permits the interpretation of the male flower as consisting of only one or two stamens The anatomy of the flower suggests that it is composed of but a single stamen whose single vascular bundle arises from a distinctive pedicellar vascular supply A subtending bract may or may not be present The so-called column has a complete vascular cylinder and is therefore to be interpreted as an ultimate branch of a compound inflorescence There is no terminal floret in such ultimate axes, but rather, the vascular supply of that axis continues beyond the insertion of the floral supplies. The inflorescence is thus open or indeterminate, and is a panicle of spikes and spikelets. Phyllotactic considerations as well as vascular anat...

Abstract: Leaves of plants possessing the C4-dicarboxy1ic acid pathway of C02 fixation have mesophyl1 cells which contain granal chloroplasts and bundle sheath cells which contain chloroplasts with varying degrees of granal development depending on the species (LAETSCH 1971). Histological studies using the Hill oxidant, tetranitro-blue-tetrazoliurn chloride suggested that non-cyclic electron flow from water was absent in the agranal bundle sheath chloroplasts of Sorghum sudanense (DOWNTON et al. 1970).

Abstract: Two Digitaria hybrids were compared with pangolagrass, Digitaria decumbens Stent., using both the light and electron microscope. The purpose of the study was to develop a diagnostic method of screening breeding lines for resistance or tolerance to pangola stunt virus (PSV). Pangolagrass from Surinam and Guyana, naturally infected with PSV, was found to have occassional bundle sheath cells with very thick cell walls. One of the two hybrids, which appeared to be highly susceptible to PSV, also showed similar thick cell walls. It had spherical particles 70 nm in diameter, resembling PSV, maize rough dwarf virus (MRDV) and rice dwarf virus (RDV). Sieve element cells of the phloem were the primary site of particles and the probable site of virus replication. The second hybrid, an apparently resistant line, was found to be completely free of thick-walled bundle sheath cells, and no viruslike particles were found in the bundle sheath or phloem cells. The presence of thick-walled bundle sheath cells appears to offer an excellent diagnostic test for PSV.

Abstract: Crown root primordia in stem of rice plants (fig. 9) originate from certain cells derived from the innermost ground meristem cells adjacent to the continuous ring of meristematic tissue which will differentiate to the peripheral cylinder of vascular bundles and fibers (PV in fig. 9). The vascular tissue between the crown root and the peripheral cylinder of the longitudinal vascular bundles of the stem originates also from the same cells. Before the crown root initiation, several cell layers are formed by one or two periclinal divisions of the innermost ground meristem cells (fig. 4). In these several cell layers, subsequently, the cells of the inner one or two layers bigin to divide transversely while the cells of the outer one or two layers bigin to divide radially somewhat later (fig. 5). At this stage, some groups of cells from the inner cell layers elongate radially and the nuclei and the nucleoli of the cells become enlarged (fig. 6). These groups of cells are the initial cells of crown root primordia as observed under ordinary microscope, also the density of the protoplasm of these cells becomes gradually higher. The same phenomena were observed in the outer cells adjacent to the crown root initial cells. These outer cells also constitute the primordia. In this stage, the initial cells bigin to divide periclinally, transversely and radially to form the crown root primordia (fig. 7). On the other hand, the inner cells which have not differentiated to crown root primordia undergo transversal division and sometimes periclinal division (fig. 8). They give rise to the vascular tissue between the crown root and the vascular system of the stem. When the sequence of the region where the initiation of crown root primordia is taking place is observed basipetally in longitudinal sections, it was found to correspond to the same region where the future sclerenchymatous elements in the peripheral cylinder of vascular bundles and fibers bigin to elongate (fig. 6). The differentiation of the peripheral cylinder of vascular bundles and fibers proceeds acropetally, these regions may migrate acropetally as the stem develops. When the distribution of the crown root primordia formed in the main stem is examined, two "primordium forming zones of crown roots" (fig. 10) were recognized in the region between the axils of Pn+1 and Pn leaves (fig. 9). These zones were observed to have a relationship to the vascular pattern of the stem. In the region between these two "primordium forming zones of crown roots" where there are few crown root primordium formations, the meristematic ring of the future peripheral vascular bundles and fibers is separated by both larger and smaller leaf traces observed in transversal sections (fig. 11).

Abstract: SUMMARY Small interfascicular and fascicular tissue blocks were excised from the hypocotyl of mature castor bean embryos. When cultured on a liquid medium containing mineral salts, sucrose, and kinetin, many of the interfascicular tissue blocks produced a cambium. Fascicular tissue blocks exhibited remarkably little development of vascular bundle tissue, particularly in the morphologically apical side of the block. Cambial development was frequently observed in this kind of tissue block, however, and was apparently not influenced by the lack of vascular bundle differentiation. Omission of kinetin from the medium prevented cambial development in both interfascicular and fascicular tissue blocks but did not lead to any further reduction of vascular bundle differentiation in the latter. It is therefore concluded that vascular bundle differentiation and cambial development represent two essentially unrelated developmental processes, both initiated in the mature embryo but each depending for its realization on different specific internal and external conditions. The precambial layer, i.e. the layer(s) considered to represent the initiated cambium, can be identified in the interfascicular zone as the innermost of two cell layers characterized by the relatively small size of the cells and nuclei. Attempts to obtain enzyme-histochemical evidence corroborating the special character of the precambial layer have been unsuccesful.

Abstract: SUMMARY The vascular connections between a leaf of the vegetative shoot part and the nectaries of the inflorescence of F. imperialis have been traced with l4C-photosynthates. The conclusion, based on the earlier observed strictly longitudinal translocation of photosynthates in the vascular bundles of the stem, is that the phyllotactical arrangement of the flowers around the stem axis deviates from that of the leaves (2/5) and approximates a 3/8 pattern.

Abstract: In some tropical grasses like sugar cane, sorghum, maize etc. two types of chloroplasts have been observed. Chloroplasts of mesophyll cells possess grana with normal stacking of thylakoids in contrast to chloroplasts of the bundle-sheath which contain numerous single thylakoids with occasional overlaps (LAETSCH 1968, BACHMANN et al. 1969). Dimorphism of chloroplasts is regarded to be a result of specialized development of plastids, proceeding via reduction of rudimentary grana (LAETSCH & PRICE 1969). Chloroplasts of different types contain Photosystem 1 and 2 in different amounts: bundle-sheath chloroplasts of sorghum have been shown to lack Photosystem 2 (WOO et al. 1970).

Abstract: The purpose of the experiment was to determine the changes of o- diphenol, ascorbic acid, and activities of polyphenol oxidase and peroxidase, accompanied with the browning by the low dose of gamma ray, in three parts of tuber tissue (cortex, vascular bundle, and pith), and to observe the relation between the browning and the changes of ihose compounds and enzyme activities. The odiphenol content increased in irradiated tabers and the increasing rate was greater in cortex and vascular bundle than in pith. The ascorbic acid content decreased with higher doses, and the decreasing rate was greater in cortex and vascular bundle than in pith. The activities of polyphenol oxidase and peroxidase also increased in irradiated tubers. The activity of polyphenol oxidase increased more in cortex than in vascular bundle and pith and the activity of peroxidase increased more in vascular bundle than in cortex and pith. ln the potato tubers in which irradiation was conducted immediately after harvest, the browning was induced within several days after irradiation. However, in the potato tubers in which irradiation was conducted about 3 months, the browning did not occur after irradiation. The former showed the increase of o-diphenol content and the activities of thesemore » enzymes, and the decrease of ascorbic acid content, the latter did not show the changes of o-diphenol and ascorbic acid and activities of the enzymes. (auth)« less

Abstract: Laterally connected vascular bundles inthenodesofsugarcane(Saccharum species cv.Pindar) stalks allowa rapid redistribution ofwateracrossthestalkshouldthevascular continuity bepartly disrupted. Tritiated watersupplied tothe roots exchanged rapidly between thexylem andstorage tissue so thatnetmovementup thestalk wasslow. Thehalf-time for exchange ina labeled stalk was about4 hoursso thatthe entire watercontentofasugarcane stalk canturnoveratleast onceinasingle day. Norapid fluxofsugarbetween xylem and phloemorxylemandstorage tissue was detected. Functional xylemcontained only lowsugarconcentrations: less than0.3% w/vinthestalk andless than0.02%w/vintheleaf. Previous reports ofhighsugarlevels (9% w/v)insugarcane stalk xylem reflect somedegree ofxylemblockage followed bya slow equilibration withfreespace sugars inthestorage tissue.

Abstract: The course of vascular bundles and its developmental pattern in monocotyledons has been reinvestigated. This shows the existence of an "inner" and an "outer" vascular system. The inner system is more extensive, three-dimensionally very complex, and "open-ended" in a distal direction, i.e., centripetally toward the apical meristem. The outer system is open-ended in basal and peripheral directions and usually poorly developed. In many monocotyledons, it is represented by the fibrous bundles in the cortex of the stem. Occasionally, the outer system is more fully developed as in Strelitzia, where it is represented by fully developed- vascular cortical bundles or as a secondary vascular tissue in those monocotyledons which show secondary growth (e.g., Dracaena, Cordyline, Pleomele). We suggest that dicotyledons differ from monocotyledons in having only an outer system. This might lead to a clarification of the phylogenetic relationship between the two groups.