Interactions between Source, Path and Sink in Determining Phloem Translocation Rate

1978 ◽  
Vol 5 (5) ◽  
pp. 665
Author(s):  
A Lang
Keyword(s):  
Hydrostatic Pressure ◽  
Sap Flow ◽  
Sieve Tube ◽  
Joint Control ◽  
Temperature Changes ◽  
Slightly Compressible ◽  
Steady Rate ◽  
Phloem Translocation ◽  
Sieve Tubes ◽  
The Individual

Treatments involving mild (5-10 Celsius degrees) temperature changes, spanning a range of mean temperatures, were imposed upon the source, path and sink regions of a translocating plant of Nymphoides geminata whilst the translocation rate was monitored. The temperature dependence (Q*10) of the rate of translocation was evaluated for each of these treatments. A new steady rate was achieved in only 3-5 min following a temperature change and was sustained for 2 h or more. Changes in rate were propagated down the sieve tubes at speeds more than ten times greater than those of sap flow, indicating that translocation involves the flow of a slightly compressible sap. The results suggest that translocation rate is normally under the joint control of source, path and sink regions of the plant. An attempt is made to assess their relative contributions to the overall control and this leads to the conclusion that, in this plant situation, the pathway predominates in controlling rate. It would seem that the individual rates of activity of source, path and sink regions are modulated by changes in the sieve tube sap concentration in their vicinity, these changes corresponding to, and being brought about rapidly by, changes in the hydrostatic pressure of this sap.

Specific Mass Transfer and Sink-Controlled Phloem Translocation in Castor Bean

1984 ◽  
Vol 11 (6) ◽  
pp. 483 ◽  
Author(s):  
J Kallarackal ◽  
JA Milburn
Keyword(s):  
Mass Transfer ◽  
Sap Flow ◽  
Ricinus Communis ◽  
Turgor Pressure ◽  
Back Pressure ◽  
Limiting Factor ◽  
Specific Mass ◽  
Phloem Sap ◽  
Phloem Translocation ◽  
Sieve Tubes

The specific mass transfer (SMT) into the fruits of Ricinus communis was measured in three different systems: (1) the intact truss, (2) fruit-thinned truss (all but one fruit removed), and (3) exuding peduncle. We found that the SMT in an intact system accords well with values reported in previous studies. But in the single-fruit and exuding systems the values were 2 and 18 times higher than the intact system, respectively. The inability of a single fruit to achieve a much higher SMT value shows that the assimilate unloading is sink-controlled. The high SMT value of the exuding system demonstrates the capacity of the sieve tubes to transport large volumes of phloem sap when turgor pressure in the sieve tubes at the sink ceases to be a limiting factor. This can be contrasted with the single-fruit system where the sink probably exerts a 'back pressure' while the assimilate supply is unlimited. The twofold increase in SMT shown by a single-fruit system is probably caused by hormone-stimulated assimilate unloading. SMT values have been used also to calculate the velocity of sap flow in the sieve tubes.

scholarly journals Evaluation of dsRNA delivery methods for targeting macrophage migration inhibitory factor MIF in RNAi-based aphid control

2021 ◽  
Author(s):  
Shaoshuai Liu ◽  
Maria Jose Ladera-Carmona ◽  
Minna M. Poranen ◽  
Aart J. E. van Bel ◽  
Karl-Heinz Kogel ◽  
...  
Keyword(s):  
Immune Responses ◽  
Artificial Diet ◽  
Sieve Tube ◽  
Feeding Strategies ◽  
Macrophage Migration ◽  
Delivery Methods ◽  
Host Immune Responses ◽  
Aphid Control ◽  
Barley Leaves ◽  
Sieve Tubes

AbstractMacrophage migration inhibitory factors (MIFs) are multifunctional proteins regulating major processes in mammals, including activation of innate immune responses. In invertebrates, MIF proteins participate in the modulation of host immune responses when secreted by parasitic organisms, such as aphids. In this study, we assessed the possibility to use MIF genes as targets for RNA interference (RNAi)-based control of the grain aphid Sitobion avenae (Sa) on barley (Hordeum vulgare). When nymphs were fed on artificial diet containing double-stranded (ds)RNAs (SaMIF-dsRNAs) that target sequences of the three MIF genes SaMIF1, SaMIF2 and SaMIF3, they showed higher mortality rates and these rates correlated with reduced MIF transcript levels as compared to the aphids feeding on artificial diet containing a control dsRNA (GFP-dsRNA). Comparison of different feeding strategies showed that nymphs’ survival was not altered when they fed from barley seedlings sprayed with naked SaMIF-dsRNAs, suggesting they did not effectively take up dsRNA from the sieve tubes of these plants. Furthermore, aphids’ survival was also not affected when the nymphs fed on leaves supplied with dsRNA via basal cut ends of barley leaves. Consistent with this finding, the use of sieve tube-specific YFP-labeled Arabidopsis reporter lines confirmed that fluorescent 21 nt dsRNACy3, when supplied via petioles or spraying, co-localized with xylem structures, but not with phloem tissue. Our results suggest that MIF genes are a potential target for insect control and also imply that application of naked dsRNA to plants for aphid control is inefficient. More efforts should be put into the development of effective dsRNA formulations.

WITHIN–TREE VARIATION IN PHLOEM CELL DIMENSIONS AND PROPORTIONS IN EUCALYPTUS GLOBULUS

IAWA Journal ◽  
2000 ◽  
Vol 21 (1) ◽  
pp. 31-40 ◽  
Author(s):  
Teresa Quilhó ◽  
Helena Pereira ◽  
Hans Georg Richter
Keyword(s):  
Wall Thickness ◽  
Eucalyptus Globulus ◽  
Tree Height ◽  
Sieve Tube ◽  
Bark Thickness ◽  
Cell Type ◽  
Fibre Width ◽  
Axial Variation ◽  
Sieve Tubes ◽  
Old Trees

The axial variation of bark thickness and quantitative anatomical features of Eucalyptus globulus bark were analysed for one site based on individual measurements of ten 15-year-old trees at six height levels (DBH, 5%, 15%, 35%, 55% and 75% of total tree height). The parameters studied were: length, tangential diameter and percentage of sieve tubes; length, width, cell wall thickness and percentage of fibres; height and percentage of rays; percentage of sclereids in the secondary phloem. Bark thickness decreases from base to top of the tree. Fibre width and wall thickness decrease from base upwards. No distinct axial patterns of variation were observed for the other biometric variables studied. Parenchyma is the main cell type of the bark (50%) followed by fibres (27.9%), rays (12.1%), sieve tubes (2.7%), and sclereids (7.3%). The cell type proportions vary significantly within the tree, i.e., parenchyma, ray and sclereid proportions decrease, fibre and sieve tube proportions increase towards the top of the tree.

Studies on the Feeding and Nutrition of Tuberolachnus Salignus (Gmelin) (Homoptera, Aphididae):

1957 ◽  
Vol 34 (3) ◽  
pp. 334-341
Author(s):  
T. E. MITTLER
Keyword(s):  
Host Plant ◽  
Sieve Tube ◽  
Normal Rate ◽  
Phloem Sap ◽  
Food Canal ◽  
Tuberolachnus Salignus ◽  
Normal Feeding ◽  
Sieve Tubes ◽  
Considerable Pressure ◽  
Salix Spp

1. A study has been made of the factors involved in the uptake of phloem sap by Tuberolachnus salignus (Gmelin) feeding on the stems of various Salix spp. 2. A method has been developed for maintaining the parthenogenetic viviparous forms of T. salignus in culture throughout the year. 3. It has been established that during normal feeding T. salignus have the tips of their stylets inserted into the phloem sieve-tubes of the host plant. 4. The phloem sieve-tube sap of intact and turgid willow stems is under considerable pressure. This pressure forces the sieve-tube mp up the stylet food canal of feeding aphids, and also causes the sieve-tube sap to exude for many hours from the cut end of embedded stylet bundles. 5. Intact and feeding T. salignus rely almost entirely on this pressure to maintain their normal rate of eieve-tube sap uptake. The aphids must, however, swallow actively in order to ingest.

Micro versus nanochannels: carbon micro-sieve tubes from biological phloem tissues for lithium–oxygen batteries

2020 ◽  
Vol 22 (2) ◽  
pp. 388-396 ◽  
Author(s):  
Zhuang Sun ◽  
Yuchen Zhang ◽  
Bin Sun ◽  
Chushu Yang ◽  
Tao Zhang
Keyword(s):  
Sieve Tube ◽  
Phloem Tissue ◽  
Sieve Tubes ◽  
Stability Issues ◽  
Lithium Oxygen Batteries

Microscale sieve-tube carbon from biological phloem tissue goes much beyond nanoscale channel carbon, avoiding clogging and alleviating stability issues.

scholarly journals Analysis of Hygrothermal Microclimatic (HTM) Parameters in Specific Food Storage Environments in Slovakia

2020 ◽  
Vol 17 (6) ◽  
pp. 2092
Author(s):  
Iveta Marková ◽  
Ivana Tureková ◽  
Jana Jaďuďová ◽  
Emília Hroncová
Keyword(s):  
Heat Exposure ◽  
Food Storage ◽  
Winter Period ◽  
Temperature Changes ◽  
Wet Bulb Globe Temperature ◽  
Cold Room ◽  
Environment Temperature ◽  
The Difference ◽  
Globe Temperature ◽  
The Individual

The quality of work environment, temperature changes and humidity must be controlled in every production process and in the locations where employees are present. The aim of this paper is to objectively assess the exposure of employees to microclimatic factors of the workplace environment: the warehouse, changing rooms, office and cold room refrigerator. Data were obtained in real working conditions. The heat stress due to cold and heat exposure in the individual locations was evaluated using the WBGT (wet bulb globe temperature) indicator. The parameters of the hygrothermal microclimate (HTM) were objectified by a QUES Temp 44/46 T spherical thermometer. The measurements were performed both in cold and hot periods of the year. The measurements confirmed standard temperatures for individual types of interiors in the winter period, but in the summer period there was a variability of results, leading to the thermal discomfort of employees. The assessment of the WBGT index revealed that nearly 80% of employees are susceptible to hypothermia as a result of thermal stress conditions. It was proven that the temperatures measured by a spherical thermometer in the hottest room were 8.62% higher than the calculated operating temperature, while the difference in the cold room refrigerator was only 1.28% higher.

Über den Zuckergehalt der Siebröhren- bzw. Siebzellensäfte von Heracleum Mantegazzianum und Picea abies (L.) KARST.

1959 ◽  
Vol 14 (4) ◽  
pp. 278-281 ◽  
Author(s):  
Hubert Ziegler ◽  
Tom E. Mittler
Keyword(s):  
Picea Abies ◽  
Sieve Tube ◽  
Vascular Bundles ◽  
Heracleum Mantegazzianum ◽  
Sieve Tubes

Sieve-tube sap from the petioles of Heracleum Mantegazzianum and Picea abies stems was obtained by severing the proboscides of aphids tapping the sieve tubes of these plants. Sucrose was the only sugar detected in the sieve-tube sap, and occurred at concentrations of 24% (Heracleum) and 10% (w/v) (Picea). Volumes of sieve-tube sap equal to 5500 sieve-tube cells of Heracleum and 50 sievetube cells of Picea exuded from severed aphid probiscides.The mouth-parts of the aphids living within hollow Heracleum petioles normally penetrate the xylem of the vascular bundles in order to reach the phloem sieve-tubes. The aphids also tap the sievetubes of isolated phloem strands.

Further theoretical analysis of concentration–pressure–flux waves in phloem transport systems

1978 ◽  
Vol 56 (8) ◽  
pp. 1086-1090 ◽  
Author(s):  
Jack M. Ferrier
Keyword(s):  
Hydrostatic Pressure ◽  
Water Flux ◽  
Sieve Tube ◽  
Phloem Transport ◽  
Time Dependent ◽  
Transport Systems ◽  
Flux Variation ◽  
Complex Interactions ◽  
Theoretical Results ◽  
Sugar Source

Theoretical results show that waves involving complex interactions between osmotic pressure, hydrostatic pressure, and fluxes of water and solute can occur in any phloem transport system surrounded by a semipermeable membrane. These results show that such waves can travel from sugar sink to sugar source as well as from sugar source to sugar sink. The time-dependent sugar concentration variation is shown to be caused largely by the time-dependent variation of the gradient of mass flow velocity in the sieve tube which is produced by the time-dependent variation of water flux across the membrane. This water flux variation is produced by a slight phase difference between osmotic and hydrostatic pressure variation. It is proposed that this phenomenon be called the concentration–pressure–flux (CPJ) wave.

Seasonal Changes in Callose Levels and Fluorescein Translocation in the Phloem of Vitis Vinifera L.

IAWA Journal ◽  
1991 ◽  
Vol 12 (3) ◽  
pp. 223-234 ◽  
Author(s):  
Roni Aloni ◽  
Carol A. Peterson
Keyword(s):  
Vitis Vinifera ◽  
Sieve Tube ◽  
Growing Season ◽  
Early Spring ◽  
Vitis Vinifera L ◽  
First Year ◽  
Secondary Phloem ◽  
Radial Gradient ◽  
Sieve Tubes ◽  
Sieve Plates

The secondary phloem of Vitis vinifera L. is characterised by a radial gradient of sieve tube diameters. Sieve tubes maturing early in the growing season have the largest diameters; those maturing late in the season have the smallest. In early spring, masses of winter dormancy callose are gradually digested in a polar radial pattern, proceeding outwards from the cambium. The fluorescent dye, fluorescein, was used to detect translocation in sieve tubes. During spring, dye translocation was first observed in the wider sieve tubes produced near the end of the previous year and wh ich had reduced amounts of callose. But translocation was not observed in the very narrow sieve tubes formed at the end of the year although they were the first to be callose free. The reactivated sieve tubes functioned for about one month. New sieve tubes differentiated three weeks after dormancy callose breakdown and started to function about one week later, so that the transition of translocation activity from the sieve tubes of the previous year to those of the current year is relatively rapid. The sieve tubes formed toward the end of the growing season (but not the narrowest ones formed at the very end of the season) function during parts of two successive seasons, while the sieve tubes forrned early in the season usually function during the first year only. Callose amounts increase gradually during summer in both the old and new sieve tubes and become relatively heavy in the old ones. At this developmental stage, translocation occurs through young sieve plates with relatively high callose deposits.

scholarly journals Evaluation of dsRNA delivery methods for targeting macrophage migration inhibitory factor MIF in RNAi-based aphid control

2021 ◽  
Author(s):  
Shaoshuai Liu ◽  
Maria Jose Ladera-Carmona ◽  
Minna M. Poranen ◽  
Aart J.E. van Bel ◽  
Karl-Heinz Kogel ◽  
...  
Keyword(s):  
Immune Responses ◽  
Artificial Diet ◽  
Sieve Tube ◽  
Feeding Strategies ◽  
Macrophage Migration ◽  
Delivery Methods ◽  
Host Immune Responses ◽  
Aphid Control ◽  
Barley Leaves ◽  
Sieve Tubes

AbstractMacrophage migration inhibitory factors (MIF) are multifunctional proteins regulating major processes in mammals, including activation of innate immune responses. In invertebrates, MIF proteins participate in the modulation of host immune responses when secreted by parasitic organisms, such as aphids. In this study, we assessed the possibility to use MIF genes as targets for RNA interference (RNAi)-based control of the grain aphid Sitobion avenae (Sa) on barley (Hordeum vulgare). When nymphs were fed on artificial diet containing double-stranded (ds)RNAs (SaMIF-dsRNAs) that target sequences of the three MIF genes SaMIF1, SaMIF2 and SaMIF3, they showed higher mortality rates and these rates correlated with reduced MIF transcript levels as compared to the aphids feeding on artificial diet containing a control dsRNA (GFP-dsRNA). Comparison of different feeding strategies showed that nymphs’ survival was not altered when they fed from barley seedlings sprayed with SaMIF-dsRNAs, suggesting they did not effectively take up dsRNA from the sieve tubes of these plants. Furthermore, aphids’ survival was also not affected when the nymphs fed on leaves supplied with dsRNA via basal cut ends of barley leaves. Consistent with this finding, the use of sieve-tube-specific YFP-labeled Arabidopsis reporter lines confirmed that fluorescent 21 nt dsRNACy3 supplied via petioles co-localized with xylem structures, but not with phloem tissue. Our results suggest that MIF genes are a potential target for insect control and also imply that application of naked dsRNA to plants for aphid control is inefficient. More efforts should be put into the development of effective dsRNA formulations.

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