Elektronenmikroskopische Untersuchungen an Ultradünnschnitten des Markstrahlparenchyms der Rotbuche — Fagus sylvatica L.

Preusser, H.-J.; Dietrichs, H. H.; Gottwald, H.

doi:10.1515/hfsg.1961.15.3.65

Cited by 33 publications

(6 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Parenchyma cells die, starch is hydrolyzed, and the sugar is metabolized in parallel with increasing lignification. Previous studies (FREY-WYSSLING and BOSSHARD 1959;PREUSSER et al 1961) indicate that mitochondria in ray parenchyma cells are damaged presumably by phenols during the earliest stage of heartwood formation. According to HIGUTCHI and SHIMADA (1967), the carbohydrate metabolism is switched over to the pentose phosphate pathway in the transition zone between the sapwood and the heartwood.…”

Section: Discussionmentioning

confidence: 96%

Infection of roots of Norway spruce (Picea abies) by Heterobasidion annosum

Stenlid

Johansson

1987

European Journal of Forest Pathology

View full text Add to dashboard Cite

Roots of 18 mature Picea abies were inoculated in situ with Heterobasidion annosum. Within one month a dry transition zone formed in advance of the growing hyphae and around non-infected wounds. After 1, 3, and 12 months, the fungal growth and the phenolic and resmous content of the root wood were determined. After 12 months, accumulation of phenolic compounds in the transition zone resulted in concentrations similar to those found in sound heartwood and 12 times higher than those found in sound sapwood. The amount of phenolic glucosides in Heterobasidion annosum-'miecied wood was higher than in the other samples. The relative toxicity of the phenolics was highest in the transition zone and lowest in the heartwood. At concentrations comparable to those in wood, transition zone phenolics were the strongest inhibitors of conidial germination in Heterobasidion annosum and sapwood phenolics were the weakest.

show abstract

Section: Discussionmentioning

confidence: 96%

Infection of roots of Norway spruce (Picea abies) by Heterobasidion annosum

Stenlid

Johansson

1987

European Journal of Forest Pathology

View full text Add to dashboard Cite

show abstract

“…The se of melamine resin turned out to be very advantageous for this study s no dehydration in ethanol-water or acetone-water series was necessary. Preusser et al (1961) already supposed that to 1 Fig. According to Maurer and Fengel (1990) the melamine resin does not enter the cell walls and does not react with cell wall components.…”

Section: Discussionmentioning

confidence: 99%

Heartwood Formation in Quebracho colorado (Schinopsis balansae Engl.): Tannin Distribution and Penetration of Extractives into the Cell Walls

Streit¹,

Fengel²

1994

HFSG

View full text Add to dashboard Cite

KeywordsTransmission electron microscopy Tannin staining Tannin distribution Lead ci tr te Densitometry Cell wall extractives Quebracho colorado Schinopsis balansae Engl. SummaryThe distribution of tannins in the cell walls of Quebracho colorado (Schinopsis balansae Engl.) heartwood was investigated by densitometric measurement of the grey levels on TEM micrographs. Lead citrate reagent (Reynolds 1963) turned out to be an appropriate staining agent s it stains phenolic extractives selectively. This method permits the investigation of the tannin distribution in cell walls at the high resolution level of transmission electron microscopy (TEM). The results obtained from observations of wood samples from the transition zone between sapwood and heartwood lead to the conclusion that the penetration of extractives into the cell walls begins in the compound middle lamella and then continues in the secondary wall layers. The impregnation of the cell wall with extractives therefore resembles the lignification process.

show abstract

“…Radial intercellular canacules between the ray cells offer a potential route for apoplastic flow driven by the transpiration (Preusser, Dietrichs, and Gottwald, 1961;Fengel, 1965;Van der Schoot and Van Bel, 1989ft). The canacules probably originate from fusion of schizogeneouslyformed intercellular spaces (Van der Schoot and Van Bel, 1989ft).…”

Section: The Raymentioning

confidence: 99%

Xylem-Phloem Exchange Via the Rays: The Undervalued Route of Transport

1990

View full text Add to dashboard Cite

The radial solute exchange between xylem and phloem is an important determinant of the nutrient distnbution and C/N economy of seed plants. Nevertheless, our knowledge of the mechanism of xylem-phloem exchange is very limited. This paper aims to integrate anatomical and physiological data about xylem-phloem exchange and focuses on the mechanisms of radial transport. Electrophysiological mapping and intracellular injection of fluorescent dyes demonstrate that stem tissue is organized in symplastic subunits specialized in either longitudinal or lateral transport. Radial orientation, anatomical and physiological organization, strong metabolic activities, relatively negative membrane potentials, and high capacities of uptake make the rays the most likely routes for symplastic xylem-to-phloem transport. Parallel apoplastic transport may occur through radial canacules between the ray cells. The symplastic xylem-to-phloem transport includes a number of steps: (a) passage across the vessel/parenchyma interface, (b) transfer in the ray, and (c) delivery from the ray into the sieve tube/companion cell complex. Large contact pits in the vessel walls give access to the ray cells, by which the solutes are accumulated through substrate/proton co-transport. Dense pitting on the tangential walls and other ultrastructural features suggest preferential symplastic transport in the radial direction. Auxiliary endo/exocytosis is under dispute. The transport step from the ray to the sieve tube/companion cell complex remains to be elucidated. In phloem-to-xylem transport, the unloading from the phloem along the stem is essentially apoplastic, but under specific conditions it may be symplastic. Further transfer to the xylem probably occurs via the symplastic route through the ray. During radial transport, important metabolic interconversions take place into either transport or storage compounds. In many trees, the metabolism of the ray cells undergoes cyclic, annual fluctuations. Complex season-bound deposition/mobilization processes in the ray cells corresponding with seasonal changes in membrane permeability and cellular organization, reflect a master-system designed to coordinate the C/N economy throughout the year.

show abstract

Elektronenmikroskopische Untersuchungen an Ultradünnschnitten des Markstrahlparenchyms der Rotbuche — Fagus sylvatica L.

Cited by 33 publications

References 12 publications

Infection of roots of Norway spruce (Picea abies) by Heterobasidion annosum

Infection of roots of Norway spruce (Picea abies) by Heterobasidion annosum

Heartwood Formation in Quebracho colorado (Schinopsis balansae Engl.): Tannin Distribution and Penetration of Extractives into the Cell Walls

Xylem-Phloem Exchange Via the Rays: The Undervalued Route of Transport

Contact Info

Product

Resources

About