The physiology of cell elongation

Heyn, A. N. J.

doi:10.1007/bf02879296

Cited by 138 publications

(79 citation statements)

References 88 publications

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“…A comparison of uptake andI incorporation betwseen (9). C) Elongation might cause an increase in uptake of sugar, and thereby increase wall synthesis, as proposed by Ochs and Pohl (14).…”

Section: Methodsmentioning

confidence: 92%

Direct and Indirect Effects of Auxin on Cell Wall Synthesis in Oat Coleoptile Tissue

Baker

Ray

1965

Plant Physiol.

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It has been observed that promotion of cell enlargement by auxin is accompanied by an increase in synthesis of cell wall material (2,3,5,6,18,25,26,27).Because auxin does not cause an increase in wall synthesis in oat coleoptile segments whose elongation is inhibited with mannitol, the increase in synthesis caused by auxin in uninhibited segments has been regarded as induced by elongation rather than directly by auxin (2,23 from the time they were cut unitil they were placed in the growth solutions. This period varied from 1 to 3 hours depending on the number of segments handled in the experiment. In the tables, initial length refers to length at time of transfer to incubation media.Experimental Treatmizents. Unless otherwise indicated, all incubation solutions contained 0.05 ms unlabelled glucose and, in those containing auxin, 3 mg per liter IAA. Uniformly C14-labelled D-glucose (from Calbiochem), 30 ,c per ,mole, was added in amounts indicated in each experiment.The incubation solutions were contained in stender dishes (37 mm diameter by 25 mm high) with a ground rim and cover. The ground surfaces were greased with white vaseline to prevent evaporation during the course of the experiment. Each dish contained 1 ml of growth solution and from 8 to 15 coleoptile segments. The dishes were held on a reciprocating shaker (120 oscillations/minute) in the dark at room temperature (about 23°). Usually less than 15 % of the glucose in the medium was absorbed by the tissue during the experiment.Preparation and Countinig of Samitples. After the incubation period the segments were removed from the stender dishes and the adhering medium was washed off by transfering them through 2 successive petri dishes of distilled water and finally passing a stream of distilled water followed by air through the central cavity of each segment. During the washing procedure the segments were in distilled water for about 8 minutes. The segments from a single growth solution were then divided into 2 or 3 groups for subsequent extraction and counting. The segments were measured to the nearest 0.1 mm by placing them on a thin glass coverslip over 1 mm ruled graph paper and observing them with a binocular dissecting microscope. The segments were then slit down 1 side and placed in 1.5 ml of 80 % ethanol contained in a screw cap vial at room temperature, to extract alcoholsoluble compounds. After 24 hours the alcohol extracts were transferred to 1.25 inch planchets. The segments were then washed in the vial with a further 1 ml of 80 % alcohol for 1 hour, the washings being added to the initial extracts on the planchets. The segments were washed with distilled water 4 times, and were then individually unrolled on a piece of plate glass and crushed by pressing a second piece of glass on top of them.

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“…A comparison of uptake andI incorporation betwseen (9). C) Elongation might cause an increase in uptake of sugar, and thereby increase wall synthesis, as proposed by Ochs and Pohl (14).…”

Section: Methodsmentioning

confidence: 92%

Direct and Indirect Effects of Auxin on Cell Wall Synthesis in Oat Coleoptile Tissue

Baker

Ray

1965

Plant Physiol.

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“…the formation of xylem cells through cambial activity, has been extensively investigated since the last century, providing detailed insights into the physiology that regulates plant cell development (Heyn, 1940;Rů zi cka et al, 2015). Experimental manipulations have additionally shown how internal factors, e.g.…”

Section: Introductionmentioning

confidence: 99%

How does climate influence xylem morphogenesis over the growing season? Insights from long-term intra-ring anatomy inPicea abies

Castagneri

Fonti

Arx

et al. 2017

Ann Bot

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Background and Aims During the growing season, the cambium of conifer trees produces successive rows of xylem cells, the tracheids, that sequentially pass through the phases of enlargement and secondary wall thickening before dying and becoming functional. Climate variability can strongly influence the kinetics of morphogenetic processes, eventually affecting tracheid shape and size. This study investigates xylem anatomical structure in the stem of Picea abies to retrospectively infer how, in the long term, climate affects the processes of cell enlargement and wall thickening.Methods Tracheid anatomical traits related to the phases of enlargement (diameter) and wall thickening (wall thickness) were innovatively inspected at the intra-ring level on 87-year-long tree-ring series in Picea abies trees along a 900 m elevation gradient in the Italian Alps. Anatomical traits in ten successive tree-ring sectors were related to daily temperature and precipitation data using running correlations.Key Results Close to the altitudinal tree limit, low early-summer temperature negatively affected cell enlargement. At lower elevation, water availability in early summer was positively related to cell diameter. The timing of these relationships shifted forward by about 20 (high elevation) to 40 (low elevation) d from the first to the last tracheids in the ring. Cell wall thickening was affected by climate in a different period in the season. In particular, wall thickness of late-formed tracheids was strongly positively related to August-September temperature at high elevation.Conclusions Morphogenesis of tracheids sequentially formed in the growing season is influenced by climate conditions in successive periods. The distinct climate impacts on cell enlargement and wall thickening indicate that different morphogenetic mechanisms are responsible for different tracheid traits. Our approach of long-term and highresolution analysis of xylem anatomy can support and extend short-term xylogenesis observations, and increase our understanding of climate control of tree growth and functioning under different environmental conditions.

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“…Thereafter, the cell wall may be irreversibly extended under the influence of the turgor to bring about the actual enlargement of the cell (1)(2)(3). The nature of this physical modification of the wall and the underlying process have remained unknown until now.…”

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confidence: 99%

Molecular basis of auxin-regulated extension growth and role of dextranase

Heyn

1981

Proc. Natl. Acad. Sci. U.S.A.

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The first step in the extension growth ofthe plant cell is a process in which the cell wall becomes ductile or plastic, after which the actual enlargement takes place passively under the influence of turgor. The nature of this process has not been explained, although much research has been carried out concerning it. In the present report, it is shown that a specific enzyme, which is identical or nearly so with dextranase (a-1,6-D-glucan 6-glucanohydrolase, EC 3.2.1.11) and is associated with the cell walls of growing coleoptiles, plays a prominent role in this process. The action ofthis enzyme is dependent on the level ofgrowth hormone, auxin, in the tissue. Under its action, certain cell wall components are broken down to yield arabinose and glucose. These sugars are also released during autolysis ofcell wall material. The molecular linkages broken in the process are probably the arabinogalactan crosslinks of the hemicellulose matrix, which are the main constituents of the wall containing arabinose. This is substantiated by the finding that dextranase can break down arabinan and compounds containing arabinose chains with the release of arabinose, just as in the action of the enzyme on the wall. The breaking of these crosslinks will impart the necessary plasticity to the wall for cell extension to occur.The essential step in auxin-regulated extension growth (elongation) of the plant cell is plasticization ("loosening") of the cell wall. Thereafter, the cell wall may be irreversibly extended under the influence of the turgor to bring about the actual enlargement of the cell (1-3). The nature of this physical modification of the wall and the underlying process have remained unknown until now.In 1968, I undertook a study of the possible involvement of enzymes in this process. Such involvement might be in agreement with findings that certain antibiotics inhibit cell elongation and plasticization of the cell wall (4-6) and that protein synthesis, as well as synthesis of DNA and RNA, is a requirement for cell elongation (7-12). In that study, the presence of enzymes in elongating coleoptiles was investigated, and several glucanases were found to be associated with the cell walls (13).In an effort to screen out the enzyme actually involved in the process of the modification of the cell wall under the influence of the hormone, the effect of the hormone concentration in the tissue on the activity of the enzymes, at optimal pH range, was studied. The activity ofonly one glucanase was found to depend on the auxin level in the tissue and to be higher at higher auxin concentration. This enzyme is dextranase (a-1,6-D-glucan 6-glucanohydrolase, EC 3.2. 1.11) (14,15).Whether this outstanding behavior is due to a special, direct sensitivity of the enzyme to the hormone or to a more complicated situation such as the interplay of more than one enzyme need not be considered at this point. The special behavior of this enzyme, however, made it first choice for being investigated as the possible "master" enzyme in the process...

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The physiology of cell elongation

Cited by 138 publications

References 88 publications

Direct and Indirect Effects of Auxin on Cell Wall Synthesis in Oat Coleoptile Tissue

Direct and Indirect Effects of Auxin on Cell Wall Synthesis in Oat Coleoptile Tissue

How does climate influence xylem morphogenesis over the growing season? Insights from long-term intra-ring anatomy inPicea abies

Molecular basis of auxin-regulated extension growth and role of dextranase

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