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

scholarly journals Microsite Influences on Variability in Douglas-Fir Seedling Development

2007 ◽  
Vol 22 (3) ◽  
pp. 156-162 ◽  
Author(s):  
Owen Burney ◽  
Michael G. Wing ◽  
Robin Rose
Keyword(s):  
Seedling Growth ◽  
Information Criterion ◽  
Seedling Development ◽  
Douglas Fir ◽  
Washington State ◽  
Diameter Growth ◽  
Strongly Correlated ◽  
Growth Change ◽  
Soil Impedance ◽  
Over Time

Abstract We examined the microsite characteristics of 6,048 Douglas-fir seedlings at three regeneration sites in Washington state. Our objective was to determine the microsite characteristics that were most influential on seedling growth change over time. We analyzed microsite influences both individually and in concert with one another through regression-based techniques. Microsite parameters included soil impedance, topographic, and physical parameter measurements that were recorded at each seedling's location. Akaike's information criterion (AIC) was used to determine combinations of microsite parameters that were most strongly correlated with seedling growth. Multiparameter models explained between 15 and 39 percent of the variance in diameter growth. Prevalent terms from the strongest multiparameter models included soil penetration, log presence, stump presence, skid road presence, and topography. Individual microsite parameters for each regeneration site were also assessed for importance in explaining diameter growth using two additional methods. The first approach was to isolate the parameters that appeared in the strongest multiparameter models and to sum and contrast the AIC weights of all models in which they appeared. The second approach was to regress single parameters against seedling diameter growth. Results varied by site for both methods. AIC weight sums revealed that topographical depression and berms, the presences of logs and stumps, and soil penetration (pounds per square inch) as measured by a penetrometer were most influential, with values ranging from 0.31 (berm) to 0.82 (log). Regression analysis revealed that topographical depression, log presence, and soil penetration were significantly related to diameter growth, explaining between 6 and 29 percent of the variance in diameter growth. Combined results from the three regeneration sites suggest that preferred planting locations are near berms, in the transition zone associated with skid roads, and in soil that is neither too loose nor too compacted. Results from the Randle and Orting sites indicate that planting in topographical depressions should be avoided. Results from Orting indicate that seedlings should not be placed near logs, and Randle findings suggest not planting next to stumps.

The extraction of photosynthate high in [11C]sucrose and its translocation in sunflower stems

1980 ◽  
Vol 58 (1) ◽  
pp. 100-107 ◽  
Author(s):  
D. B. Hayden ◽  
D. S. Fensom ◽  
R. G. Thompson
Keyword(s):  
Half Life ◽  
Indirect Evidence ◽  
Phloem Transport ◽  
Water Soluble ◽  
Vascular Bundles ◽  
Soluble Extract ◽  
Xylem Transport ◽  
Phloem Translocation ◽  
Water Soluble Extract ◽  
The Individual

A technique has been developed to biosynthesize a water-soluble extract of 11C-labelled photosynthate high in [11C]sucrose. The extract can be produced in less than 1 half-life (20 min) and is of high activity. When 11C-labelled extract was fed to the individual vascular bundles of other living plants, 11C was taken up and translocated, and on the basis of direct and indirect evidence it was largely in the form of [11C]sucrose.11C-labelled extract, if fed to a flap or gentle scraping on the surface of a sunflower stem (or corn, cow-parsnip, pine, or elm) was translocated both apically and basally from the feed point. Incisions into xylem vessels produced very rapid tracer movements which seemed to be associated with xylem vessel liquid cavitation and also transpiration pull. Shallower cuts produced translocation patterns similar to 11CO2 leaf feedings and are thought to be largely in the phloem. Phloem transport was blocked by ice chilling; xylem transport was only slightly affected by ice, if at all. Phloem translocation profiles often displayed steps at the front of mass flow, and later appeared to have peaks of activity moving along them. The movements were sometimes rapid (>6 cm min−1) and appeared to be complex, as if different channels were conducting at different speeds in parallel.

scholarly journals The Coumarin Glucoside, Esculin, Reveals Rapid Changes in Phloem-Transport Velocity in Response to Environmental Cues

2018 ◽  
Vol 178 (2) ◽  
pp. 795-807 ◽  
Author(s):  
Kirsten Knox ◽  
Andrea Paterlini ◽  
Simon Thomson ◽  
Karl Oparka
Keyword(s):  
Phloem Transport ◽  
Environmental Cues ◽  
Rapid Changes ◽  
Transport Velocity

Aspects arising from the use of inhibitors in phloem transport studies

1980 ◽  
Vol 58 (7) ◽  
pp. 816-820 ◽  
Author(s):  
Johannes Willenbrink
Keyword(s):  
Carbon Metabolism ◽  
Cell Membranes ◽  
Cytochalasin B ◽  
Potassium Cyanide ◽  
Phloem Transport ◽  
Vascular Bundles ◽  
Pelargonium Zonale ◽  
Transport Studies ◽  
Central Bundle ◽  
Sugar Phosphates

Experiments on the movement of 14C-assimilates through dissected vascular bundles of Pelargonium zonale are reviewed. Potassium cyanide (KCN) applied to the central bundle causes localized, reversible blockage of transport. Both antimycin and atractylate, but not ouabain inhibit the movement of metabolites through the phloem. The proton ionophore, CCCP completely suppresses translocation at 10−7 M, however, cell membranes are damaged. Valinomycin applied to cut bundles causes serious disturbances in carbon metabolism as shown by the increased label in sugar phosphates. Cytochalasin B does not affect translocation. Limitations on conclusions drawn from inhibitor studies are discussed.

scholarly journals KELCH F-BOX protein positively influences Arabidopsis seed germination by targeting PHYTOCHROME-INTERACTING FACTOR1

2018 ◽  
Vol 115 (17) ◽  
pp. E4120-E4129 ◽  
Author(s):  
Manoj Majee ◽  
Santosh Kumar ◽  
Praveen Kumar Kathare ◽  
Shuiqin Wu ◽  
Derek Gingerich ◽  
...  
Keyword(s):  
Seed Germination ◽  
Feedback Loop ◽  
Double Mutant ◽  
Seedling Development ◽  
Activation Tagging ◽  
Environmental Cues ◽  
In Planta ◽  
F Box Protein ◽  
Physiological And Biochemical ◽  
Over Time

Seeds employ sensory systems that assess various environmental cues over time to maximize the successful transition from embryo to seedling. Here we show that the Arabidopsis F-BOX protein COLD TEMPERATURE-GERMINATING (CTG)-10, identified by activation tagging, is a positive regulator of this process. When overexpressed (OE), CTG10 hastens aspects of seed germination. CTG10 is expressed predominantly in the hypocotyl, and the protein is localized to the nucleus. CTG10 interacts with PHYTOCHROME-INTERACTING FACTOR 1 (PIF1) and helps regulate its abundance in planta. CTG10-OE accelerates the loss of PIF1 in light, increasing germination efficiency, while PIF1-OE lines fail to complete germination in darkness, which is reversed by concurrent CTG10-OE. Double-mutant (pif1 ctg10) lines demonstrated that PIF1 is epistatic to CTG10. Both CTG10 and PIF1 amounts decline during seed germination in the light but reaccumulate in the dark. PIF1 in turn down-regulates CTG10 transcription, suggesting a feedback loop of CTG10/PIF1 control. The genetic, physiological, and biochemical evidence, when taken together, leads us to propose that PIF1 and CTG10 coexist, and even accumulate, in the nucleus in darkness, but that, following illumination, CTG10 assists in reducing PIF1 amounts, thus promoting the completion of seed germination and subsequent seedling development.

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.

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