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.

Temporal and spatial expression of hexose transporters in developing tomato (Lycopersicon esculentum) fruit

2005 ◽  
Vol 32 (9) ◽  
pp. 777 ◽  
Author(s):  
Stephen J. Dibley ◽  
Michael L. Gear ◽  
Xiao Yang ◽  
Elke G. Rosche ◽  
Christina E. Offler ◽  
...  
Keyword(s):  
Lycopersicon Esculentum ◽  
Fruit Ripening ◽  
Tomato Fruit ◽  
Vascular Bundles ◽  
Hexose Transporter ◽  
Transporter Protein ◽  
Protein Levels ◽  
Parenchyma Cells ◽  
Storage Parenchyma ◽  
Post Transcriptional Regulation

Correlative physiological evidence suggests that membrane transport into storage parenchyma cells is a key step in determining hexose levels accumulated in tomato (Lycopersicon esculentum Mill.) fruit (Ruan et al. 1997). Expression of three previously identified hexose transporter genes (LeHT1, 2 and 3) demonstrated that LeHT3, and to a lesser extent LeHT1, are the predominant transporters expressed in young fruit (10 d after anthesis; DAA). Expression of both transporters dropped sharply until 24 DAA, after which only LeHT3 expression remained at detectable levels through to fruit ripening. LeHT2 was not expressed substantially until the onset of fruit ripening. For fruit at both 10 and 30 DAA, LeHT3 transcripts were detected in storage parenchyma cells of the outer pericarp tissue, but not in vascular bundles or the first layer of parenchyma cells surrounding these bundles. In contrast to LeHT gene expression, hexose transporter protein levels were maximal between 20 and 30 DAA, which corresponded to the period of highest hexose accumulation. The delayed appearance of transporter protein is consistent with some form of post-transcriptional regulation. Based on these analyses, LeHT3 appears to be responsible for the rapid hexose accumulation in developing tomato fruit.

scholarly journals The Sugar Content of Cell Walls and Intercellular Spaces in Sugar-Cane Stems and its Relation to Sugar Transport

1965 ◽  
Vol 18 (5) ◽  
pp. 959 ◽  
Author(s):  
JS Hawker
Keyword(s):  
Aqueous Phase ◽  
Sugar Cane ◽  
Cell Walls ◽  
Sugar Content ◽  
Sugar Transport ◽  
Intercellular Spaces ◽  
Parenchyma Cells ◽  
Storage Parenchyma

In sugar-cane stems which contain large amounts of sucrose the concentration of sucrose in the volume external to the vacuoles was found to approach the concentration present in the vacuoles (20%). It was shown that this sucrose is situated mainly in the aqueous phase of the cell walls and intercellular spaces of the storage parenchyma cells.

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.

scholarly journals Localization of vicilin peptidohydrolase in the cotyledons of mung bean seedlings by immunofluorescence microscopy.

1978 ◽  
Vol 79 (1) ◽  
pp. 10-19 ◽  
Author(s):  
B Baumgartner ◽  
K T Tokuyasu ◽  
M J Chrispeels
Keyword(s):  
Vigna Radiata ◽  
Mung Bean ◽  
Immunofluorescence Microscopy ◽  
De Novo ◽  
Protein Bodies ◽  
Vascular Bundles ◽  
Large Protein ◽  
Parenchyma Cells ◽  
Storage Parenchyma ◽  
Monospecific Antibodies

Vicilin peptidohydrolase, the protease that hydrolyzes the reserve proteins in the cotyledons of mung bean (Vigna radiata) seedlings, has been localized intracellularly by immunofluorescence microscopy using monospecific antibodies against the enzyme and rhodamine-coupled goat-anti-rabbit immunoglobulin G's. The enzyme can first be visualized after 3 days of seedling growth and is associated with small foci within the cytoplasm of the storage parenchyma cells farthest from the vascular bundles. On the 4th day of growth, the protease is also present in the numerous large protein bodies within these cells. Vicilin peptidohydrolase is known to be synthesized de novo starting on the 3rd day of growth. Our observations are therefore consistent with the interpretation that the enzyme is synthesized in the cytoplasm and subsequently transported to the protein bodies.

The morphology of grain abscission in Zizania aquatica

1980 ◽  
Vol 58 (21) ◽  
pp. 2269-2273 ◽  
Author(s):  
H. B. Hanten ◽  
G. E. Ahlgren ◽  
J. B. Carlson
Keyword(s):  
Wild Rice ◽  
Cell Walls ◽  
Vascular Tissue ◽  
Embryo Sac ◽  
Middle Lamella ◽  
Abscission Zone ◽  
Rice Grains ◽  
Zizania Aquatica ◽  
Parenchyma Cells ◽  
Anatomical Evidence

The anatomical development of the abscission zone in grains of Zizania aquatica L. was correlated with development of the embryo. The abscission zone is well developed when the embryo sac is mature. Soon after pollination, the first anatomical evidence of abscission appears as plasmolysis of the separation layer parenchyma cells. This is followed by separation of the layers by dissolution of the middle lamella and fragmentation of cell walls. Persistence of intact vascular tissue and presence of a surrounding cone-shaped mass of lignified cells may be involved in abscission of wild rice grains.

Localisation structurale et ultrastructurale d'activités peroxydasiques dans les parois du mésophylle et des fibres en cours de lignification chez l'alfa (Stipa tenacissima)

1984 ◽  
Vol 62 (12) ◽  
pp. 2644-2649 ◽  
Author(s):  
M. Harche
Keyword(s):  
Peroxidase Activity ◽  
Oxidase Activity ◽  
Cell Walls ◽  
Secondary Wall ◽  
Outer Part ◽  
Potassium Cyanide ◽  
Primary Wall ◽  
Stipa Tenacissima ◽  
Parenchyma Cells

Using diaminobenzidine as substrate, peroxidase activity was localized in the walls of parenchyma cells and differentiating fibres. In mature fibres and parenchyma a slight activity could be recognized in primary walls only. In parenchyma cells, peroxidase activity was fairly inhibited with heat, potassium cyanide, and aminotriazole, which could indicate the presence of catalase within the cell walls. However, in plasmodesmatal regions peroxidases were- resistant to the above inhibitors. Syringaldazine oxidase activity was present only in the primary wall and the outer part of the secondary wall of differentiating fibres. The parallelism between lignification and peroxidase activity in the secondary walls supports the hypothesis of the involvement of these enzymes in the lignification process.

scholarly journals Anatomy, Cell Wall Structure and Topochemistry of Water-Logged Archaeological wood aged 5,200 and 4,500 years

IAWA Journal ◽  
2008 ◽  
Vol 29 (1) ◽  
pp. 55-68 ◽  
Author(s):  
Katarina Čufar ◽  
Jožica Gričar ◽  
Martin Zupančič ◽  
Gerald Koch ◽  
Uwe Schmitt
Keyword(s):  
Cell Types ◽  
Wall Structure ◽  
Normal Wood ◽  
Uv Absorbance ◽  
Archaeological Wood ◽  
Transmission Electron ◽  
Parenchyma Cells ◽  
Prehistoric Settlements ◽  
And Storage ◽  
Uv Microspectrophotometry

Evaluating the state of deterioration of water-logged archaeological wood is necessary in order to select treatments for its conservation and storage, particularly in the case of valuable archaeological artefacts. For this purpose archaeological wood of ash (Fraxinus sp.) and oak (Quercus sp.) buried in water-logged conditions at prehistoric settlements on the Ljubljansko barje (Ljubljana moor), Slovenia, aged approx. 5,200 and 4,500 years, was investigated by means of light microscopy (LM), transmission electron microscopy (TEM) and cellular UV-microspectrophotometry (UMSP). LM and TEM revealed that the ash wood aged 5,200 years was the least preserved. The secondary walls of fibres, vessels and parenchyma cells were considerably thinner than in normal wood, indicating distinct degradation. TEM and UMSP additionally revealed strong delignification of the remaining parts of the secondary walls of all cell types. The compound middle lamellae appeared structurally intact, but had lower UV-absorbance than normal wood of the same species. The cell corners were topochemically unchanged, as shown by high analogue UV-absorbance. The UV-absorbance maxima at a wavelength of 278 nm corresponded to those of hardwood lignins. The oak heartwood was generally better preserved than the ash wood. Within each species, the 4,500- year-old samples generally appeared better preserved than those 5,200 years old.

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