scholarly journals Monitoring Phloem Unloading and Post-Phloem Transport by Microperfusion of Attached Wheat Grains

1994 ◽  
Vol 104 (1) ◽  
pp. 7-16 ◽  
Author(s):  
N. Wang ◽  
D. B. Fisher
Keyword(s):  
Phloem Transport ◽  
Phloem Unloading ◽  
Wheat Grains

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 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.

The bigger picture - phloem seen through horticultural eyes

2000 ◽  
Vol 27 (6) ◽  
pp. 615 ◽  
Author(s):  
Rod L. Bieleski
Keyword(s):  
Cell Death ◽  
Photosynthetic Capacity ◽  
Dry Weight ◽  
Phloem Transport ◽  
Full Length ◽  
Flower Bud ◽  
Phloem Unloading ◽  
Feedback Reduction ◽  
Sink Capacity ◽  
Linear Body

Horticulturalists manipulate phloem transport to achieve horticulturally-desirable results. The resulting crop behaviour can help show how phloem works. In apple, the use of dwarfing rootstocks and pruning management has greatly increased fruit sink capacity at the expense of root and shoot sinks. Annual fruit yield can exceed100 t ha –1 and account for 65% of total photosynthate. If photosynthetic capacity exceeds fruit sink capacity, there can be either a feedback reduction in photosynthesis, or accumulation of phloem sugars in the fruit apoplast. In sugarcane, the sink is a linear body encasing the full length of the phloem strands from leaf to root. Lateral unloading must occur along the full length of the phloem. Unloading or loading may occur in the same segment of phloem depending on conditions. In the ornamental lily and daylily, the developing flower bud is a powerful sink, doubling in dry weight each 48 h in the week of development from small bud to opening. Once the flower is open, the phloem changes rapidly from unloading behaviour as the tepals become vigorous exporters. The change in behaviour may be coupled with processes mediating senescence and cell death. Implications to phloem function are discussed.

scholarly journals A Proposed Drought Response Equation Added to the Münch-Horwitz Theory of Phloem Transport

2020 ◽  
Author(s):  
John D. Goeschl ◽  
Lifeng Han
Keyword(s):  
Experimental Evidence ◽  
Turgor Pressure ◽  
Sieve Tube ◽  
Phloem Transport ◽  
Root Tips ◽  
Phloem Unloading ◽  
Rate Kinetics ◽  
Response Equation ◽  
Membrane Bound ◽  
Kinetics Of

AbstractTheoretical and experimental evidence for an effect of sieve tube turgor pressure on the mechanisms of phloem unloading near the root tips during moderate levels of drought stress is reviewed. An additional, simplified equation is proposed relating decreased turgor pressure to decreased rate kinetics of membrane bound transporters. The effect of such a mechanism would be to decrease phloem transport Speed, but increase Concentration and Pressure, and thus prevent or delay negative Pressure in the phloem. Experimental evidence shows this mechanism precedes and exceeds a reduction in stomatal conductance.

Transport of zinc and manganese to developing wheat grains

1995 ◽  
Vol 95 (3) ◽  
pp. 449-455 ◽  
Author(s):  
J. N. Pearson ◽  
Z. Rengel ◽  
C. F Jenner ◽  
R. D. Graham
Keyword(s):  
Wheat Grains
Sign in / Sign up

Export Citation Format

Share Document