Sieve tube longevity in white ash (Fraxinus americana) studied with a new histochemical test for the identification of sugar

1979 ◽  
Vol 57 (6) ◽  
pp. 650-656 ◽  
Author(s):  
E. Zamski ◽  
M. H. Zimmermann
Keyword(s):  
Sieve Tube ◽  
Cambial Activity ◽  
Fraxinus Americana ◽  
Starch Grains ◽  
Active Season ◽  
White Ash ◽  
Histochemical Test ◽  
Short Period ◽  
Young Leaves ◽  
Sieve Tubes

A histochemical test for functioning sieve tubes, based on the 5-diazouracil sugar reaction, has been used to identify functioning sieve tubes in Fraxinus americana L. The plant material was lyophilized, treated with the reagent, and sectioned in a cryostat. Before the resumption of cambial activity, when buds are still closed (late April – early May), starch grains of the storage tissues in bark and wood disappear and rays, cambrium, and phloem are loaded with sugars. In early spring, sugars begin to accumulate in last year's sieve tubes, especially in those which had not been fully differentiated in the previous active season and those which were functioning but had formed toward the end of the active season. Girdling experiments, carried out during May, showed that translocation in the phloem does occur, to some extent, during the period when the buds develop and the young leaves grow. The reactivated sieve tubes provide the channel of translocation to developing buds for sugars, formed of the dissolution of starch grains. The first early-phloem sieve tubes are formed at the end of May and loaded with sugars during June. There seems to be a short period of simultaneous import into young leaves via reactivated phloem and export via new phloem. After this, last year's sieve tubes are crushed. A noticeable pressure flow does not appear in the main stem until mid-June.

Studies on the Phloem Sealing Mechanism in Ricinus Fruit Stalks

1983 ◽  
Vol 10 (6) ◽  
pp. 561 ◽  
Author(s):  
J Kallarackal ◽  
JA Milburn
Keyword(s):  
Electron Microscopy ◽  
Sieve Tube ◽  
Sieve Plate ◽  
Tube System ◽  
Phloem Sap ◽  
Starch Grains ◽  
P Protein ◽  
Sieve Tubes ◽  
Sealing Mechanism ◽  
Sieve Plates

Fruit stalks of R. communis were made to exude phloem sap by repeated slicing at intervals of a few minutes. Samples 1 mm thick from the fruit stalks were fixed for electron microscopy. Samples were also fixed and processed for electron microscopy from previously intact (non-exuding) fruit stalks. Examination of the sieve tubes from these two different samples showed predominantly open sieve-plate pores in the exuding fruit stalk. The sieve plates of the non-exuding fruit stalk showed occlusion of the sieve-plate pores by P-protein. The starch grains from the broken plastids also had characteristic distributions. The implications of these observations are discussed in relation to comprehending the mechanism by which sieve-plate pores become choked, and so sealing the sieve-tube system as a result of injury.

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.

FRAXINUS AMERICANA, WHITE ASH

2014 ◽  
pp. 901-905
Author(s):  
Henry John Elwes ◽  
Augustine Henry
Keyword(s):  
Fraxinus Americana ◽  
White Ash

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.

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.

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