Symplasmic phloem unloading and post-phloem transport during bamboo internode elongation

2020 ◽  
Vol 40 (3) ◽  
pp. 391-412 ◽  
Author(s):  
Lin Deng ◽  
Pengcheng Li ◽  
Caihua Chu ◽  
Yulong Ding ◽  
Shuguang Wang
Keyword(s):  
Parenchyma Cell ◽  
Phloem Transport ◽  
Assimilate Transport ◽  
Vascular Bundles ◽  
Radial Transport ◽  
Phloem Unloading ◽  
Transport Pathways ◽  
Bamboo Shoots ◽  
Parenchyma Cells ◽  
Symplastic Pathway

Abstract In traditional opinions, no radial transportation was considered to occur in the bamboo internodes but was usually considered to occur in the nodes. Few studies have involved the phloem unloading and post-phloem transport pathways in the rapid elongating bamboo shoots. Our observations indicated a symplastic pathway in phloem unloading and post-unloading pathways in the culms of Fargesiayunnanensis Hsueh et Yi, based on a 5,6-carboxyfluorescein diacetate tracing experiment. Significant lignification and suberinization in fiber and parenchyma cell walls in maturing internodes blocked the apoplastic transport. Assimilates were transported out of the vascular bundles in four directions in the inner zones but in two directions in the outer zones via the continuum of parenchyma cells. In transverse sections, assimilates were outward transported from the inner zones to the outer zones. Assimilates transport velocities varied with time, with the highest values at 0):00 h, which were affected by water transport. The assimilate transport from the adult culms to the young shoots also varied with the developmental degree of bamboo shoots, with the highest transport velocities in the rapidly elongating internodes. The localization of sucrose, glucose, starch grains and the related enzymes reconfirmed that the parenchyma cells in and around the vascular bundles constituted a symplastic pathway for the radial transport of sugars and were the main sites for sugar metabolism. The parenchyma cells functioned as the ‘rays’ for the radial transport in and between vascular bundles in bamboo internodes. These results systematically revealed the transport mechanism of assimilate and water in the elongating bamboo shoots.

Cellular pathways of source leaf phloem loading and phloem unloading in developing stems of Sorghum bicolor in relation to stem sucrose storage

2015 ◽  
Vol 42 (10) ◽  
pp. 957 ◽  
Author(s):  
Ricky J. Milne ◽  
Christina E. Offler ◽  
John W. Patrick ◽  
Christopher P. L. Grof
Keyword(s):  
Sorghum Bicolor ◽  
Cell Walls ◽  
Phloem Loading ◽  
Vascular Bundles ◽  
Phloem Unloading ◽  
Parenchyma Cells ◽  
Storage Parenchyma ◽  
Sucrose Storage ◽  
Cellular Pathways ◽  
And Storage

Cellular pathways of phloem loading in source leaves and phloem unloading in stems of sweet Sorghum bicolor (L.) Moench were deduced from histochemical determinations of cell wall composition and from the relative radial mobilities of fluorescent tracer dyes exiting vascular pipelines. The cell walls of small vascular bundles in source leaves, the predicted site of phloem loading, contained minimal quantities of lignin and suberin. A phloem-loaded symplasmic tracer, carboxyfluorescein, was retained within the collection phloem, indicating symplasmic isolation. Together, these findings suggested that phloem loading in source leaves occurs apoplasmically. Lignin was restricted to the walls of protoxylem elements located in meristematic, elongating and recently elongated regions of the stem. The apoplasmic tracer, 8-hydroxypyrene-1,3,6-trisulfonic acid, moved radially from the transpiration stream, consistent with phloem and storage parenchyma cells being interconnected by an apoplasmic pathway. The major phase of sucrose accumulation in mature stems coincided with heavy lignification and suberisation of sclerenchyma sheath cell walls restricting apoplasmic tracer movement from the phloem to storage parenchyma apoplasms. Phloem unloading at this stage of stem development followed a symplasmic route linking sieve elements and storage parenchyma cells, as confirmed by the phloem-delivered symplasmic tracer, 8-hydroxypyrene-1,3,6-trisulfonic acid, moving radially from the stem phloem.

scholarly journals Symplasmic phloem unloading and radial post-phloem transport via vascular rays in tuberous roots of Manihot esculenta

2019 ◽  
Vol 70 (20) ◽  
pp. 5559-5573 ◽  
Author(s):  
Rabih Mehdi ◽  
Christian E Lamm ◽  
Ravi Bodampalli Anjanappa ◽  
Christina Müdsam ◽  
Muhammad Saeed ◽  
...  
Keyword(s):  
Manihot Esculenta ◽  
Phloem Transport ◽  
Xylem Parenchyma ◽  
Phloem Unloading ◽  
Tuberous Roots ◽  
Parenchyma Cells

Efficient starch storage in young xylem parenchyma cells is supported by symplasmic phloem unloading and post-phloem transport via parenchymatic vascular rays in the tuberous roots of cassava.

scholarly journals Leaf morphology of 89 tree species from a lowland tropical rain forest (Atlantic forest) in South Brazil

2004 ◽  
Vol 47 (6) ◽  
pp. 933-943 ◽  
Author(s):  
Maria Regina Torres Boeger ◽  
Luiz Carlos Alves ◽  
Raquel Rejane Bonatto Negrelle
Keyword(s):  
Atlantic Forest ◽  
Tree Species ◽  
Leaf Morphology ◽  
High Efficiency ◽  
Cell Layer ◽  
Mineral Soil ◽  
Parenchyma Cell ◽  
Nutrient Content ◽  
Vascular Bundles ◽  
South Brazil

We examined the leaf morphology and anatomy of 89 tree species growing in an area of coastal Atlantic Forest in South Brazil. The majority of the species (> 75%) had small (notophyll and microphyll) elliptical simple leaves with entire margins. These leaves presented a typical anatomical structure consisting of a single epidermal cell layer, single palisade parenchyma cell layer, and spongy parenchyma with 5 to 8 cell layers. The sclerenchyma was limited to the vascular bundles. The majority of the tree species (91%) had leaves with mesomorphic characteristics. Few species depicted leaves with xeromorphic features as would be expected in such oligotrophic sandy soil. These mesomorphic features appeared to be associated to high efficiency mechanisms for nutrient cycling that compensated for the low nutrient content of the mineral soil.

Physiological Basis for the Different Phloem Mobilities of Chlorsulfuron and Clopyralid

Weed Science ◽  
1990 ◽  
Vol 38 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Malcolm D. Devine ◽  
Hank D. Bestman ◽  
William H. Vanden Born
Keyword(s):  
Leaf Tissue ◽  
Phloem Transport ◽  
Assimilate Transport ◽  
Herbicide Application ◽  
Irreversible Binding ◽  
Sensitive Species ◽  
Physiological Basis ◽  
Treated Leaf ◽  
Phloem Translocation ◽  
Leaf Disks

Foliar-applied clopyralid was translocated much more readily than chlorsulfuron in the phloem of Tartary buckwheat plants. This result was not due to greater penetration of clopyralid into the treated leaf or to greater retention of chlorsulfuron in the cuticle. Experiments with excised leaf disks indicated that chlorsulfuron was taken up more readily by the leaf tissue and accumulated in the tissue to a higher concentration than clopyralid. Both herbicides effluxed readily from the tissue after transfer to herbicide-free medium, indicating that the accumulation was not due to irreversible binding within the tissue. Chlorsulfuron (2.8 nmol) applied with14C-sucrose reduced14C export from the treated leaf. Chlorsulfuron also reduced export of14C following exposure of the treated leaf to14CO2at 6, 12, or 24 h after herbicide application. This effect of chlorsulfuron could be partially reversed by pretreating the plants with a combination of 1 mM valine, leucine, and isoleucine. In similar experiments clopyralid had no effect on assimilate transport. It is concluded that phloem translocation of chlorsulfuron in sensitive species is limited by a rapid, indirect effect on phloem transport that reduces both its own translocation and that of assimilate.

scholarly journals Colonization of Fiber Cells by Colletotrichum graminicola in Wounded Maize Stalks

2007 ◽  
Vol 97 (4) ◽  
pp. 438-447 ◽  
Author(s):  
C. Venard ◽  
L. Vaillancourt
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Pathogen Resistance ◽  
Vascular Bundles ◽  
Colletotrichum Graminicola ◽  
Wild Type ◽  
Wound Site ◽  
Fiber Cells ◽  
Parenchyma Cells ◽  
Maize Stalks

Colonization of wounded maize stalks by a wild-type strain of Colletotrichum graminicola was compared with colonization by a C. graminicola mutant that is avirulent on maize leaves, and by a wild-type strain of C. sublineolum that is normally a pathogen of sorghum but not maize. Local infection by all strains at the wound site resulted in formation of primary lesions consisting of disintegrated parenchyma cells beneath an intact rind and epidermis. However, subsequent rapid longitudinal expansion of the primary lesion occurred only in infections with the wild-type C. graminicola strain, and proceeded specifically through the fiber cells associated with the vascular bundles and the rind. Hyphae emerged from the fiber cells to produce discontinuous secondary lesions. There was no evidence that C. graminicola is a vascular wilt pathogen. Resistance of wounded cv. Jubilee maize stalks to the mutant strain of C. graminicola and to C. sublineolum was associated with restriction of colonization and spread of the pathogen through the fibers, as well as with the limitation of localized destruction of parenchyma cells at the wound site.

scholarly journals Two-compartment model of inner medullary vasculature supports dual modes of vasopressin-regulated inner medullary blood flow

2010 ◽  
Vol 299 (1) ◽  
pp. F273-F279 ◽  
Author(s):  
Julie Kim ◽  
Thomas L. Pannabecker
Keyword(s):  
Blood Flow ◽  
Blood Flow Rate ◽  
Outer Zone ◽  
Compartment Model ◽  
Transverse Dimension ◽  
Vessel Diameter ◽  
Functional Coupling ◽  
Vascular Bundles ◽  
Transport Pathways ◽  
Vasa Recta

The outer zone of the renal inner medulla (IM) is spatially partitioned into two distinct interstitial compartments in the transverse dimension. In one compartment (the intercluster region), collecting ducts (CDs) are absent and vascular bundles are present. Ascending vasa recta (AVR) that lie within and ascend through the intercluster region (intercluster AVR are designated AVR2) participate with descending vasa recta (DVR) in classic countercurrent exchange. Direct evidence from former studies suggests that vasopressin binds to V1 receptors on smooth muscle-like pericytes that regulate vessel diameter and blood flow rate in DVR in this compartment. In a second transverse compartment (the intracluster region), DVR are absent and CDs and AVR are present. Many AVR of the intracluster compartment exhibit multiple branching, with formation of many short interconnecting segments (intracluster AVR are designated AVR1). AVR1 are linked together and connect intercluster DVR to AVR2 by way of sparse networks. Vasopressin V2 receptors regulate multiple fluid and solute transport pathways in CDs in the intracluster compartment. Reabsorbate from IMCDs, ascending thin limbs, and prebend segments passes into AVR1 and is conveyed either upward toward DVR and AVR2 of the intercluster region, or is retained within the intracluster region and is conveyed toward higher levels of the intracluster region. Thus variable rates of fluid reabsorption by CDs potentially lead to variable blood flow rates in either compartment. Net flow between the two transverse compartments would be dependent on the degree of structural and functional coupling between intracluster vessels and intercluster vessels. In the outermost IM, AVR1 pass directly from the IM to the outer medulla, bypassing vascular bundles, the primary blood outflow route. Therefore, two defined vascular pathways exist for fluid outflow from the IM. Compartmental partitioning of V1 and V2 receptors may underlie vasopressin-regulated functional compartmentation of IM blood flow.

Berry pericarp ontogenesis from fertilization to maturity of Vitis vinifera L. var Merlot

OENO One ◽  
1997 ◽  
Vol 31 (3) ◽  
pp. 109 ◽  
Author(s):  
Monique Fougère-Rifot ◽  
H.-S. Park ◽  
Jacques Bouard
Keyword(s):  
Cell Number ◽  
Grape Berry ◽  
Ovary Wall ◽  
Vascular Bundles ◽  
Berry Skin ◽  
Wall Thinning ◽  
Fruit Setting ◽  
Parenchyma Cells ◽  
Pulp Cells ◽  
The One

<p style="text-align: justify;">Grape-flower ovary transformations is followed from fertilized flower to berry came to maturity. Cell transformations are studied, especially vacuolar tannins, starch and cell wall thinning :</p><p style="text-align: justify;">- From fruit setting to veraison, cell number of carpellary wall located between outer epidennis and vascular bundles is multiplied by 2.</p><p style="text-align: justify;">- Cell size increase considerably but by different means according to tissues: hypodennis cells elongate tangentially while inner parenchyma cells round.</p><p style="text-align: justify;">- Vacuolar tannins content in internal parenchyma cells decrease as soon as ovary is fertilized. During growth and veraison tannic cell number decrease. At maturity, only the most external cells (superficial hypodennis) still have vacuolar tannins. All the other cells of ovary wall have no more tannins.</p><p style="text-align: justify;">- Wall thickness decrease begins as soon as growth starts and this phenomena is continuous to maturity. The wall thinning down begins near the locules of ovary and is propagated towards the ouside of pericarp.</p><p style="text-align: justify;">- Amyloplasts disappear progressively. At maturity, there is scarcely no more startch in grape-berry.</p><p style="text-align: justify;">In short, except cells of berry skin, all the cells of ovary wall enlarge, lost their vacuolar tannins and the cell walls become very thin ; they are pulp cells.</p><p style="text-align: justify;">ln the pericarp of mature berry, hypodennis is very thin (less than 50 μm in places and 2-5 layers of cells). Pulp or flesh takes up a great place.</p><p style="text-align: justify;">This work is consecutived to the one on ovary before fertilization (FOUGÈRE-RIFOT et al., 1995) that shown 20 development stages from ovary primordia to the fertilized egg. From fertilized ovary to mature berry the development of pericarp is divided into 5 stages (stages 21 to 25) :</p><p style="text-align: justify;">- Stage 21 : first appearance of ovary inflation. Ovary takes a round shape. The thickness of carpellary wall is about 300 μm.</p><p style="text-align: justify;">- Stage 22 : fruit setting. Vacuolar tannins of inner parenchym disappear.</p><p style="text-align: justify;">- Stage 23 : berry growth.</p><p style="text-align: justify;">- Stage 23A : transformation of inner parenchym into pulp.</p><p style="text-align: justify;">- Stage 238 : transformation of deep hypodennis into pulp</p><p style="text-align: justify;">- Stage 23C : pulp cell enlargement.</p><p style="text-align: justify;">- Stage 24 : veraison. The definitive size of the berry is about reached.</p><p style="text-align: justify;">- Stage 24A : beginning of veraison. The hypodermis has still some thick walls.</p><p style="text-align: justify;">- Stage 248 : end of veraison. The hypodennis cells near the outer pulp cells change into pulp cells</p><p style="text-align: justify;">- Stage 25: maturity. Pulp is became very developped.</p>

scholarly journals Phloem Transport Velocity Varies over Time and among Vascular Bundles during Early Cucumber Seedling Development

2013 ◽  
Vol 163 (3) ◽  
pp. 1409-1418 ◽  
Author(s):  
Jessica A. Savage ◽  
Maciej A. Zwieniecki ◽  
N. Michele Holbrook
Keyword(s):  
Phloem Transport ◽  
Seedling Development ◽  
Vascular Bundles ◽  
Cucumber Seedling ◽  
Transport Velocity ◽  
Over Time

Permineralized monocotyledons from the Middle Eocene Princeton chert (Allenby Formation) of British Columbia: Alismataceae

1989 ◽  
Vol 67 (9) ◽  
pp. 2636-2645 ◽  
Author(s):  
Diane M. Erwin ◽  
Ruth A. Stockey
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Vascular Bundles ◽  
Western North America ◽  
Ground Tissue ◽  
Abaxial Surface ◽  
Parenchyma Cells ◽  
In Series ◽  
Thin Walled ◽  
Tannin Cells

One small monocotyledon petiole, 1.8 × 1.5 mm wide, has been recovered from the Princeton chert in the Middle Eocene Allenby Formation, British Columbia. The petiole, rectangular in transverse outline, shows approximately 36 circular to oval-shaped vascular bundles within aerenchymatous ground tissue that includes tannin cells. The epidermis is underlain by a discontinuous hypodermis of thick-walled, pitted cells. Vascular bundles are in five series: (I) a median U-shaped arc of 11 – 13 bundles; (II) an abaxial arc of 6 bundles located below the main arc; (III) two short abaxial arcs of 3 bundles each; (IV) 2 bundles just below the abaxial surface; and (V) an adaxial series of 7 bundles that show an inverse orientation to those bundles in series I–IV. Larger bundles are collateral, with a protoxylem lacuna encircled by a ring of 9 – 14 thin-walled parenchyma cells, a relatively well-developed phloem strand, and one to three thin-walled metaxylem elements. Based on bundle arrangement, orientation, and morphology, the fossil petiole most closely resembles those of the Butomaceae and Alismataceae. This new species, Heleophyton helobiaeoides Erwin and Stockey gen. et sp.nov., in the Princeton chert flora, documents the presence of the Alismataceae in the Middle Eocene of western North America and provides further evidence that the locality represents an ancient aquatic ecosystem.

Source physiology and assimilate transport: the interaction of sucrose metabolism, starch storage and phloem export in source leaves and the effects on sugar status in phloem

2000 ◽  
Vol 27 (6) ◽  
pp. 497 ◽  
Author(s):  
Ewald Komor
Keyword(s):  
Genetic Manipulation ◽  
Sieve Tube ◽  
Phloem Loading ◽  
Assimilate Transport ◽  
Vascular Bundles ◽  
Ambient Conditions ◽  
Sucrose Transport ◽  
Carbon Export ◽  
Export Rate ◽  
Long Day

Phloem loading of sucrose is decisive for the speed of mass flow, because sucrose is the dominant solutein the sieve tube sap of nearly all plant species. The export rate of carbon is linearly correlated to the concentration of sucrose in green leaves. Saturation of export was not observed, because surplus of assimilates is converted to starch, a process which is regulated by the sucrose level in the cytosol. Consequently, an increase of sucrose synthesis by overexpression of SPS did not enhance carbon export (at least under normal ambient conditions). Saturation of sucrose export could be observed only in experimental systems, where sucrose was fed directly to the phloem (e.g. in Ricinus seedling) or where constraints on transport activity were imposed by genetic manipulation either on the transporters (e.g. in sucrose transporter antisense plants) or on the path of sucrose (e.g. in plants trans ormed with TMV movement protein, or by incubation in salts). The balance between carbon storage and carbon export is subject to adaptation to meet growth requirements under special circumstances. For example, in a starch-deficient mutant, the day time export rate is nearly doubled compared to wild type plants. Furthermore, plants under short day illumination greatly accelerated starch storage compared to plants under long day illumination (a modulation which persists even a few days after a shift to long day conditions). Plants with a higher assimilation rate due to elevated ambient CO2 increase the nightly carbon export rate, whereas the export rate in day time rate appeared to work at its upper limit. The overall efficiency of sucrose export and incorporation into biomass is ca 0.65, which is close to the theoretical value of 0.75. Sucrose transport along the phloem strands is modulated according to the input at the source, but the individual phloem strands show also partial coordination with respect to sucrose concentrations (as revealed by NMR-imaging), especially obvious after physical interruption of some vascular bundles.

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