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1.
Suaeda monoica Forssk. ex J. F. Gmel was found to possess the C 4 pathway of photosynthesis. The succulent leaves of Suaeda lack a green bundle sheath formation but have a layer of chlorenchyma, containing large and centripetally arranged chloroplasts, which surrounds the water tissue. We suggest that the proximity of a chlorenchymatous cell layer to the vascular bundles is not necessary for the operation of the C 4 pathway. 相似文献
3.
Two-dimensional electrophoresis was performed on proteins of bundle sheath and mesophyll cells isolated from the C 4 grass Digitaria sanguinalis (L.) Scop. Two-dimensional maps of these proteins were constructed and ribulose-1,5-biphosphate carboxylase and phosphoenolpyruvate carboxylase were identified. Of the total number of proteins found in both cell types, 36% were found only in bundle sheath cells, 17% only in mesophyll cells, and 47% in both cell types. By comparison, the distributions of 48 enzymes assayed in these cell types were 35%, 21%, and 44%, respectively. Protein patterns were also compared with C4 plants exhibiting different decarboxylation pathways and, in both bundle sheath and mesophyll cells, proteins were found which were unique to each species. Bundle sheath proteins of one C4 species were found to be more like bundle sheath proteins of another C4 species than like mesophyll proteins of the same species. 相似文献
4.
Arundinella hirta L. is a C 4 plant having an unusual C 4 leaf anatomy. Besides mesophyll and bundle sheath cells, A. hirta leaves have specialized parenchyma cells which look morphologically like bundle sheath cells but which lack vascular connections and are located between veins, running parallel to them. Activities of phosphoenolpyruvate and ribulose-1,5-bisphosphate carboxylases and phosphoenolpyruvate carboxykinase, NADP-and NAD-malic enzymes were determined for whole leaf extracts and isolated mesophyll protoplasts, specialized parenchyma cells, and bundle sheath cells. The data indicate that A. hirta is a NADP-malic enzyme type C 4 species. In addition, specialized parenchyma cells and bundle sheath cells are enzymatically alike. Compartmentation of enzymes followed the C 4 pattern with phosphoenolpyruvate carboxylase being restricted to mesophyll cells while ribulose-1,5-bisphosphate carboxylase and decarboxylating enzymes were restricted to bundle sheath and specialized parenchyma cells. 相似文献
5.
The origin and early development of procambium and associated ground meristem of major and minor veins have been examined in the leaf blades of seven C 4 grass species, representing different taxonomic groups and the three recognized biochemical C 4 types (NAD-ME, PCK, and NADP-ME). Comparisons were made with the C 3 species, Festuca arundinacea. In “double sheath” (XyMS+) species ( Panicum effusum, Eleusine coracana, and Sporoboìus elongatus), the procambium of major veins gives rise to xylem, phloem, and a mestome sheath; associated ground meristem differentiates into PCA (“C 4 mesophyll”) tissue and the PCR (“Kranz”) sheath. Development in the C 3 species parallels this pattern, except that associated ground meristem differentiates into mesophyll and a parenchymatous bundle sheath. In contrast, major vein procambium of “single sheath” (XyMS–) species ( Panicum bulbosum, Digitaria brownii, and Cymbopogon procerus) differentiates into xylem, phloem and a PCR sheath; associated ground meristem gives rise to PCA tissue. These observations of major vein development support W. V. Brown's hypothesis that the PCR sheaths of “double sheath” (XyMS+) C 4 grasses are homologous with the parenchymatous bundle sheaths of C 3 grasses, while in “single sheath” (XyMS–) C 4 species they are homologous with the mestome sheath. Although there are some similarities in the development of the major and minor vascular bundle procambium in the C 4 species examined, the ontogeny of the smaller minor veins is characterized by a precocious delineation of the PCR sheath layer that may even precede the appearance of the distinctive cytological features of ground meristem and procambium. This contracted development in minor veins appears to be related to their close spacing in mature leaves and to their comparatively late appearance during leaf ontogeny. 相似文献
6.
Background and AimsCleomaceae is one of 19 angiosperm families in which C 4 photosynthesis has been reported. The aim of the study was to determine the type, and diversity, of structural and functional forms of C 4 in genus Cleome.MethodsPlants of Cleome species were grown from seeds, and leaves were subjected to carbon isotope analysis, light and scanning electron microscopy, western blot analysis of proteins, and in situ immunolocalization for ribulose bisphosphate carboxylase oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC). Key ResultsThree species with C 4-type carbon isotope values occurring in separate lineages in the genus ( Cleome angustifolia, C. gynandra and C. oxalidea) were shown to have features of C 4 photosynthesis in leaves and cotyledons. Immunolocalization studies show that PEPC is localized in mesophyll (M) cells and Rubisco is selectively localized in bundle sheath (BS) cells in leaves and cotyledons, characteristic of species with Kranz anatomy. Analyses of leaves for key photosynthetic enzymes show they have high expression of markers for the C 4 cycle (compared with the C 3–C 4 intermediate C. paradoxa and the C 3 species C. africana). All three are biochemically NAD-malic enzyme sub-type, with higher granal development in BS than in M chloroplasts, characteristic of this biochemical sub-type. Cleome gynandra and C. oxalidea have atriplicoid-type Kranz anatomy with multiple simple Kranz units around individual veins. However, C. angustifolia anatomy is represented by a double layer of concentric chlorenchyma forming a single compound Kranz unit by surrounding all the vascular bundles and water storage cells. ConclusionsNAD-malic enzyme-type C 4 photosynthesis evolved multiple times in the family Cleomaceae, twice with atriplicoid-type anatomy in compound leaves having flat, broad leaflets in the pantropical species C. gynandra and the Australian species C. oxalidea, and once by forming a single Kranz unit in compound leaves with semi-terete leaflets in the African species C. angustifolia. The leaf morphology of C. angustifolia, which is similar to that of the sister, C 3–C 4 intermediate African species C. paradoxa, suggests adaptation of this lineage to arid environments, which is supported by biogeographical information. 相似文献
7.
The C 4 grass Arundinella hirta exhibits a unique C 4 anatomy, with isolated Kranz cells (distinctive cells) and C 4-type expression of photosynthetic enzymes in the leaf sheath and stem as well as in the leaf blade. The border zones between these organs are pale green. Those between the leaf blade and sheath and between the sheath and stem are called the lamina joint and sheath pulvinus, respectively, and are involved in gravity sensing. We investigated the structure and localization of C 3 and C 4 photosynthetic enzymes in these tissues. In both zones the epidermis lacked stomata. The inner tissue was composed of parenchyma cells and vascular bundles. The parenchyma cells were densely packed with small intercellular spaces and contained granal chloroplasts with large starch grains. No C 4-type cellular differentiation was recognized. Western blot analysis showed that the lamina joint and pulvinus accumulated substantial amounts of phospho enolpyruvate carboxylase (PEPC), pyruvate,Pi dikinase (PPDK), and ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco). Immunogold electron microscopy revealed PEPC in the cytosol and both PPDK and rubisco in the chloroplasts of parenchyma cells, suggesting the occurrence of C 3 and C 4 enzymes within a single type of chlorenchyma cell. These data indicate that the lamina joint and pulvinus have unique expression patterns of C 3 and C 4 enzymes, unlike those in C 4-type anatomy. 相似文献
8.
Ecotypic differences in the photosynthetic carbon metabolism of Mollugo verticillata were studied. Variations in C 3 and C 4 cycle activity are apparently due to differences in the activities of enzymes associated with each pathway. Compared to C 4 plants, the activities of C 4 pathway enzymes were generally lower in M. verticillata, with the exception of the decarboxylase enzyme, NAD malic enzyme. The combined total carboxylase enzyme activity of M. verticillata was greater than that of C 3 plants, possibly accounting for the high photosynthetic rates of this species. Unlike either C 3 or C 4 plants, ribulose bisphosphate carboxylase was present in both mesophyll and bundle sheath cell chloroplasts in M. verticillata. The localization of this enzyme in both cells in this plant, in conjunction with an efficient C 4 acid decarboxylation mechanism most likely localized in bundle sheath cell mitochondria, may account for intermediate photorespiration levels previously observed in this species. 相似文献
9.
The succulent, cylindrical leaves of the C 4 dicot Portulaca grandiflora possess three distinct green cell types: bundle sheath cells (BSC) in radial arrangement around the vascular bundles; mesophyll cells (MC) in an outer layer adjacent to the BSC; and water storage cells (WSC) in the leaf center. Unlike typical Kranz leaf anatomy, the MC do not surround the bundle sheath tissue but occur only in the area between the bundle sheath and the epidermis. Intercellular localization of photosynthetic enzymes was characterized using protoplasts isolated enzymatically from all three green cell types. 相似文献
10.
Summary Plants with the C 4 dicarboxylic acid pathway of photosynthetic CO 2 fixation are generally nutritionally inferior to C 3 (Calvin cycle) plants as foodstuff for herbivores. A possible contributing factor to this nutritional inferiority is the concentration, in C 4 plants, of large quantities of nutritional material in very tough, thick-walled vascular bundle sheath cells which herbivores may not be able to break down. Experiments with 10 species of grass-hoppers from different areas in the United States revealed large numbers of unbroken bundle sheath cells, contents intact, in fecal pellets produced when the grasshoppers were fed C 4 vegetation. We conclude that the material stored in C 4 bundle sheath cells is at least partially unavailable to herbivores, and that this may contribute to the observed nutritional inferiority of C 4 vegetation. 相似文献
11.
In order to elucidate the evolution of C 4 syndrome, the taxonomic relationships, leaf anatomy, and ecological and global distribution of C 3 and C 4 species in the genus Rhynchospora were investigated. The anatomical observation for 181 species revealed that 26 C 4 species occurred within the Capitatae group of the subgenus Haplostyleae, a natural group showing highly advanced morphological characteristics, together with several C 3 species. In spite of there being rather few C 4 species, they possessed two kinds of Kranz anatomical structure differing from each other in the location of Kranz cells. Some C 3 species of Capitatae showed radial arrangement in mesophyll cells surrounding vascular bundles, which is distinguished from typical non-Kranz anatomy. The C 4 species extended their ecological ranges from wet habitats to dry savanna grasslands, while the C 3 species showed the best development in wet habitats. The C 3 species were widespread from tropical to temperate regions with partial range extension into subarctic regions of both hemispheres, showing conspicuously high concentration of species in the New World, but being absent from arid climatic regions. The C 4 species were distributed mostly in tropics and subtropics, showing two separate distributional centers in South and Central America and in Tropical Asia and Australia. The range of C 4 species was nearly completely included in the C 3 range. In conclusion, it seems that in Rhynchospora the C 4 syndrome evolved relatively recently, and arose in at least two separate phylogenetic trends in the tropics and the subtropics, more probably in the Neotropics. 相似文献
12.
Ultrastructural studies of leaves of seven Panicum species in or closely related to the Laxa group and classified as C 3, C 4 or C 3-C 4 intermediate were undertaken to examine features associated with C 3 and C 4 photosynthesis. The C 3 species Panicum rivulare Trin. had few organelles in bundle sheath cell profiles (2 chloroplasts, 1.1 mitochondria, and 0.3 peroxisomes per cell section) compared to an average of 10.6 chloroplasts, 17.7 mitochondria, and 3.2 peroxisomes per bundle sheath cell profile for three C 3-C 4 species, Panicum milioides Nees ex Trin., Panicum decipiens Nees ex Trin. and Panicum schenckii Hack. However, two other C 3 species, Panicum laxum Sw. and Panicum hylaeicum Mez, contained about 0.7, 0.5, and 0.3 as many chloroplasts, mitochondria, and peroxisomes, respectively, as in bundle sheath cell profiles of the C 3-C 4 species. Chloroplasts and mitochondria in bundle sheath cells were larger than those in mesophyll cells for the C 4 species Panicum prionitis Griseb. and the C 3-C 4 species, but in C 3 species the organelles were similar in size or were smaller in the bundle sheath cells. The C 3-C 4 species and P. laxum and P. hylaeicum exhibited an unusually close association of organelles in bundle sheath cells with mitochondria frequently surrounded in profile by chloroplasts. The high concentrations in bundle sheath cells of somewhat larger organelles than in mesophyll cells correlates with the reduced photorespiration of the C 3-C 4 species. 相似文献
13.
Diffusion of inorganic carbon into isolated bundle sheath cells from a variety of C 4 species was characterized by coupling inward diffusion of CO 2 to photosynthetic carbon assimilation. The average permeability coefficient for CO 2 ( PCO2) for five representatives from the three decarboxylation types was approximately 20 micromoles per minute per milligram chlorophyll per millimolar, on a leaf chlorophyll basis. The average value for the NAD-ME species Panicum miliaceum (10 determinations) was 26 with a standard deviation of 6 micromoles per minute per milligram chlorophyll per millimolar, on a leaf chlorophyll basis. A PCO2 of at least 500 micromoles per minute per milligram chlorophyll per millimolar was determined for cells isolated from the C 3 plant Xanthium strumarium. It is concluded that bundle sheath cells are one to two orders of magnitude less permeable to CO 2 than C 3 photosynthetic cells. These data also suggest that CO 2 diffusion in bundle sheath cells may be made up of two components, one involving an apoplastic path and the other a symplastic (plasmodesmatal) path, each contributing approximately equally. 相似文献
14.
Background and AimsLeaf venation in many C 4 species is characterized by high vein density, essential in facilitating rapid intercellular diffusion of C 4 photosynthetic metabolites between different tissues (mesophyll, bundle sheath). Greater vein density has been hypothesized to be an early step in C 4 photosynthesis evolution. Development of C 4 vein patterning is thought to occur from either accelerated or prolonged procambium formation, relative to ground tissue development. MethodsCleared and sectioned tissues of phylogenetically basal C 3 Flaveria robusta and more derived C 4 Flaveria bidentis were compared for vein pattern in mature leaves and vein pattern formation in developing leaves. Key ResultsIn mature leaves, major vein density did not differ between C 3 and C 4 Flaveria species, whereas minor veins were denser in C 4 species than in C 3 species. The developmental study showed that both major and minor vein patterning in leaves of C 3 and C 4 species were initiated at comparable stages (based on leaf length). An additional vein order in the C 4 species was observed during initiation of the higher order minor veins compared with the C 3 species. In the two species, expansion of bundle sheath and mesophyll cells occurred after vein pattern was complete and xylem differentiation was continuous in minor veins. In addition, mesophyll cells ceased dividing sooner and enlarged less in C 4 species than in C 3 species. ConclusionsLeaf vein pattern characteristic to C 4 Flaveria was achieved primarily through accelerated and earlier offset of higher order vein formation, rather than other modifications in the timing of vein pattern formation, as compared with C 3 species. Earlier cessation of mesophyll cell division and reduced expansion also contributed to greater vein density in the C 4 species. The relatively late expansion of bundle sheath and mesophyll cells shows that vein patterning precedes ground tissue development in C 4 species.Key words: Bundle sheath, C4 photosynthesis evolution, Flaveria, heterochrony, leaf development, mesophyll, vein density, vein pattern formation 相似文献
15.
Composite bundles are not simply a type of vascular bundles, but an integrated host/parasite interface. We investigated their structure in tubers of Langsdorffia and Balanophora. Composite bundles in both genera have similar components: 1) a central mass of host vascular tissues among which are located large parasite transfer cells; 2) a sheath of parasite parenchyma surrounding the central host vascular tissues; 3) specialized conducting tissues in the sheath; and 4) apical meristems composed of both host and parasite meristematic cells. Sheath parenchyma is recognizable from parasite tuber matrix by having thinner cell walls, and, especially in Langsdorffia, by the presence of collapsed matrix cells between the bundle sheath and tuber matrix. Sheath-conducting tissues consist of densely cytoplasmic transfer cells and small sieve tube members; in Langsdorffia, tracheary elements are also present. These sheath bundles connect with vascular bundles of the tuber matrix. Direct host/parasite contact only occurs by means of parasite transfer cells in the composite bundles. There is no xylem-xylem contact at the host/parasite interface. Abundance of parasite transfer cells suggests that they play an important role in nutrient absorption and translocation. 相似文献
16.
C4-like plants represent the penultimate stage of evolution from C3 to C4 plants. Although Coleataenia prionitis (formerly Panicum prionitis) has been described as a C4 plant, its leaf anatomy and gas exchange traits suggest that it may be a C4-like plant. Here, we reexamined the leaf structure and biochemical and physiological traits of photosynthesis in this grass. The large vascular bundles were surrounded by two layers of bundle sheath (BS): a colorless outer BS and a chloroplast-rich inner BS. Small vascular bundles, which generally had a single BS layer with various vascular structures, also occurred throughout the mesophyll together with BS cells not associated with vascular tissue. The mesophyll cells did not show a radial arrangement typical of Kranz anatomy. These features suggest that the leaf anatomy of C. prionitis is on the evolutionary pathway to a complete C4 Kranz type. Phosphoenolpyruvate carboxylase (PEPC) and pyruvate, Pi dikinase occurred in the mesophyll and outer BS. Glycine decarboxylase was confined to the inner BS. Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) accumulated in the mesophyll and both BSs. C. prionitis had biochemical traits of NADP-malic enzyme type, whereas its gas exchange traits were close to those of C4-like intermediate plants rather than C4 plants. A gas exchange study with a PEPC inhibitor suggested that Rubisco in the mesophyll could fix atmospheric CO2. These data demonstrate that C. prionitis is not a true C4 plant but should be considered as a C4-like plant. 相似文献
17.
Light microscopic examination of leaf cross-sections showed that Flaveria brownii A. M. Powell exhibits Kranz anatomy, in which distinct, chloroplast-containing bundle sheath cells are surrounded by two types of mesophyll cells. Smaller mesophyll cells containing many chloroplasts are arranged around the bundle sheath cells. Larger, spongy mesophyll cells, having fewer chloroplasts, are located between the smaller mesophyll cells and the epidermis. F. brownii has very low CO 2 compensation points at different O 2 levels, which is typical of C 4 plants, yet it does show about 4% inhibition of net photosynthesis by 21% O 2 at 30°C. Protoplasts of the three photosynthetic leaf cell types were isolated according to relative differences in their buoyant densities. On a chlorophyll basis, the activities of phosphoenolpyruvate carboxylase and pyruvate, Pi dikinase (carboxylation phase of C 4 pathway) were highest in the larger mesophyll protoplasts, intermediate in the smaller mesophyll protoplasts, and lowest, but still present, in the bundle sheath protoplasts. In contrast, activities of ribulose 1,5-bisphosphate carboxylase, other C 3 cycle enzymes, and NADP-malic enzyme showed a reverse gradation, although there were significant activities of these enzymes in mesophyll cells. As indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the banding pattern of certain polypeptides of the total soluble proteins from the three cell types also supported the distribution pattern obtained by activity assays of these enzymes. Analysis of initial 14C products in whole leaves and extrapolation of pulse-labeling curves to zero time indicated that about 80% of the CO 2 is fixed into C 4 acids (malate and aspartate), whereas about 20% of the CO 2 directly enters the C 3 cycle. This is consistent with the high activity of enzymes for CO 2 fixation by the C 4 pathway and the substantial activity of enzymes of the C 3 cycle in the mesophyll cells. Therefore, F. brownii appears to have some capacity for C 3 photosynthesis in the mesophyll cells and should be considered a C 4-like species. 相似文献
18.
Complementary to our previous project on the molecular phylogeny of Camphorosmeae, the leaf anatomy of ca. 35 species including all non-Australian and selected Australian species was studied by use of light microscopy. Nine anatomical leaf types were described, compared to previous classifications, and discussed with regard to their putative evolution on the background of phylogenetic trees. Particular emphasis was given to the relationships between the C 3 and C 4 leaf types: Chenolea type (C 3), Eokochia type (C 3), Neokochia type (C 3), Sedobassia type (C 3/C 4 intermediate), Bassia prostrata type (C 4), B. muricata type (C 4), B. eriantha type, B. lasiantha type (C 4), Camphorosma type (C 4). The main results and conclusions were: (1) Two unusual new C 3 leaf types: Chenolea with microfenestrate chlorenchyma, Eokochia with unique complex vascular bundles; (2) Sedobassia interpreted as anatomically C 3/C 4 intermediate by kranz-like bundle sheath cells is the first C 3/C 4 intermediate in Camphorosmeae and found in a derived position; (3) Neokochia type detected as the likely starting point for all four C 4 leaf types and for the C 3/C 4 intermediate; (4) hypodermis of C 4 types originated from outermost chlorenchyma layer of C 3 types and lost multiple times during further evolution; (5) atriplicoid Bassia. lasiantha type without water storage tissue evolved from kochioid B. muricata type; (6) two independent gains of C 4 photosynthesis, one in Bassia and one in Camphorosma; (7) depending on the lineage, leaf architecture remains comparatively stable (Australian Camphorosmeae) or shows an unexpected plasticity ( Bassia scoparia group). 相似文献
19.
A total of 112 species in 18 genera in the Portulacaceae were investigated anatomically for the presence or absence of the chlorenchymatous bundle sheath cells around the vascular bundles: C4 or Kranz anatomy. Twenty species in only one genus, Portulaca L. of all the taxa investigated possesses the C4 or Kranz anatomy. All others have the C3 anatomy. 相似文献
20.
The ultrastructural aspects of Cyperus iria leaves showing the C 4 syndrome and the typical C 3 species, Carex siderosticta, in the Cyperaceae family were examined. C. iria exhibited the chlorocyperoid type, showing an unusual Kranz structure with vascular bundles completely surrounded by two
bundle sheaths. The cellular components of the inner Kranz bundle sheath cells were similar to those found in the NADP-ME
C 4 subtype, having centrifugally arranged chloroplasts with greatly reduced grana and numerous starch grains. Their chloroplasts
contained convoluted thyla-koids and a weakly-developed peripheral reticulum, although it was extensive mostly in mesophyll
cell chloroplasts. The outer mestome bundle sheath layer was sclerenchymatous and generally devoid of organelles, but had
unevenly thickened walls. Suberized lamellae were present on its cell walls, and they became polylamellate when traversed
by plasmodesmata. Mesophyll cell chloroplasts showed well-stacked grana with small starch grains. In C. siderosticta, vascular bundles were surrounded by the inner mestome sheath and the outer parenchymatous bundle sheath with intercellular
spaces. The mestome sheath cells degraded in their early development and remained in a collapsed state, although the suberized
lamellae retained polylamellate features. Plastids with a crystalline structure, sometimes membrane-bounded, were found in
the epidermal cells. The close interveinal distance was 35–50 μm in C. iria, whereas it was 157–218 μm in C. siderosticta. These ultrastructural characteristics were discussed in relation to their photosynthetic functions. 相似文献
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