On the Growth Mechanism of Root Hairs

Ekdahl, Ivar

doi:10.1111/j.1399-3054.1957.tb06986.x

Cited by 18 publications

(3 citation statements)

References 30 publications

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“…Early studies using pectinase revealed an inhibitory effect of this enzyme on pollen tube growth at higher concentrations (Brewbaker and Kwack 1964) and on root hair elongation (Cormack 1956;Ekdahl 1957;Jackson 1959). Roggen and Stanley (1969), however, found that Pyrus communis pollen tube growth could be stimulated by addition of moderate pectinase concentrations.…”

Section: Discussionmentioning

confidence: 94%

Pectin and the role of the physical properties of the cell wall in pollen tube growth of Solanum chacoense

Parre

Geitmann

2004

Planta

257

225

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The cell wall is one of the structural key players regulating pollen tube growth, since plant cell expansion depends on an interplay between intracellular driving forces and the controlled yielding of the cell wall. Pectin is the main cell wall component at the growing pollen tube apex. We therefore assessed its role in pollen tube growth and cytomechanics using the enzymes pectinase and pectin methyl esterase (PME). Pectinase activity was able to stimulate pollen germination and tube growth at moderate concentrations whereas higher concentrations caused apical swelling or bursting in Solanum chacoense Bitt. pollen tubes. This is consistent with a modification of the physical properties of the cell wall affecting its extensibility and thus the growth rate, as well as its capacity to withstand turgor. To prove that the enzyme-induced effects were due to the altered cell wall mechanics, we subjected pollen tubes to micro-indentation experiments. We observed that cellular stiffness was reduced and visco-elasticity increased in the presence of pectinase. These are the first mechanical data that confirm the influence of the amount of pectins in the pollen tube cell wall on the physical parameters characterizing overall cellular architecture. Cytomechanical data were also obtained to analyze the role of the degree of pectin methyl-esterification, which is known to exhibit a gradient along the pollen tube axis. This feature has frequently been suggested to result in a gradient of the physical properties characterizing the cell wall and our data provide, for the first time, mechanical support for this concept. The gradient in cell wall composition from apical esterified to distal de-esterified pectins seems to be correlated with an increase in the degree of cell wall rigidity and a decrease of visco-elasticity. Our mechanical approach provides new insights concerning the mechanics of pollen tube growth and the architecture of living plant cells.

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Section: Discussionmentioning

confidence: 94%

Pectin and the role of the physical properties of the cell wall in pollen tube growth of Solanum chacoense

Parre

Geitmann

2004

Planta

257

225

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“…Both develop unidimensionally, elongating rapidly at the tip and bursting at the tip under osmotic stress. In any speculations concerning the roles of calcium, however, the metabolism of carbohydrates such as cellulose, callose and pectin must be considered (Ekdahl, 1957). In each system, the secondary cell wall and middle lamellae are absent, while callose is present; lignin is also absent, or present in only minor amounts, in pollen and root hairs.…”

Section: Germination Of Small Populations Of Ornithogalum Virens Pollmentioning

confidence: 99%

The Essential Role of Calcium Ion in Pollen Germination and Pollen Tube Growth

Brewbaker

Kwack

1963

American J of Botany

894

291

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Brewbaker, James L., and Beyoung H. Kwack. (U. Hawaii, Honolulu.) The essential role of calcium ion in pollen germination and pollen tube growth. Amer. Jour. Bot. 50(9): 859–865. Illus. 1963.—A pollen population effect occurs whenever pollen grains are grown in vitro. Small pollen populations germinate and grow poorly if at all, under conditions which support excellent growth of large pollen populations. The pollen population effect is overcome completely by a growth factor obtained in water extracts of many plant tissues. This factor is shown to be the calcium ion, and its action confirmed in 86 species representing 39 plant families. Other ions (K+, Mg++, Na+) serve in supporting roles to the uptake or binding of calcium. The high requirement of calcium (300–5000 ppm, as Ca (NO3)2·4H2O, for optimum growth) and low calcium content of most pollen may conspire to give calcium a governing role in the growth of pollen tubes both in vitro and in situ. It is suspected that ramifications of this role extend to the self‐incompatibilities of plants and to the curious types of arrested tube growth distinguishing, for example, the orchids. A culture medium which proved its merit in a wide variety of pollen growth studies included, in distilled water, 10% sucrose, 100 ppm H3BO3, 300 ppm Ca (NO3)2·4H2O, 200 ppm MgSO4·7H2O and 100 ppm KNO3.

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“…Glucan catabolism has been noted during incubation o,f sections excised from the pea epicotyl (19) aiid coleoptiles o,f wheat (21), oat (16,25) and maize (17). Paritially purified preparations of these enzymes effec.tively reduce the tenisile strength of dead primary walls (24), enhance the elongation of iliving oat coleop-*tile sections (22) and bring about the swelling of root hairs (7). It (8,18).…”

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confidence: 99%

Indoleacetic Acid and the Synthesis of Glucanases and Pectic Enzymes

Datko

Maclachlan

1968

Plant Physiol.

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Abstract. Indoleacetic acid (IAA) and/or inhibitors of DNA, RNA or protein synthesis were added to the apex of decapitated seedlings of Pisum sativum L. var. Alaska. At various times up to 4 days, enzymic protein was extraoted from a segment of epicotyl immediately below the apex and assayed for its ability to hydrolyse polysaccharides or their derivatives. With the exception of am;ylase, the total amounts per segment of all of the tested enzymes increased due to IAA treatment. The development of j3-1,4-glucanase (cellulase) activity per unit of protein or fresh weight proceeded according to a typical sigmoid induction curve. Pectinase was formed for about 2 days in control segments and IAA treatment resulted in continued synthesis for at least another 2 days provided cell division took place. 64,3-glucanase and pectinesterase activities were only enhanced by IAA to the extent that total protein levels increased. Reaction mechanisms for these effects and functions for the enzymes during growth are discussed.One aipproach to the problem of elucidating me,chanisms of hormone-regulated morphogenesis is to search for enzyme activities which increase after hormone treatment, choosing for investigation those enzymes which catalyse rea,dtions that could be essential for growth responises. Thi.s paper reports effects of indoleacetic acid ()IAA) on the activities of 4 pollysaccharidases and an esterase in the apical region o,f the epicotyl of decapitated pea seeddings.Enzymes which hydrolyze wall materials were selected becaulse several IAA-dependent changes in morphology oif the pea epicotyl appear to require a remodeling or loosening of primary wail structure. The hormone causes lateral cell expansion, cell division, disintegration of the walll!s o)f swoLllen cells, lacunae formation, and root generation (9, 27).Dtu,ring these events, there is a rapid and massive net synthesis of DNA, RNA and protein and a partitcularly marked increase in specific activity o-f the enzyme celilulase (8, 9 (8,18). The substrate for 8-1,3-glucanase was derived from a glucan (pachymnan) which contains only /-1,3-linkages (6). Methods for preparing the carboxymethyl derivatives and for assaying its hydrolase were described by Clarke and Stone (5). Pectinase iis so designated in this paper because the viscosimetric assay method (2) does not di,stinguish beitween polygailacturonase and pectin transeliminase (!lyase) activity (1).Amylase acetivity was estimated by measuring the rate of loss of ioidine-comiplexing power oif starch isoluttions (29). The resul-ts could be uIsed to calculate the ralte of formation of reducing groups by assuming that the staroh-iodine color disappears when the chain length falts below 40 anhydroglucose units. With (pea enzyme these calcu-lations gave valuefs for amylase activity which were comparable to direc(t measurements of the rate of production of reducing power (Somogyi method). It i's probable, therefore, that the enzyme was an ce-(endo-) amylase.Pectinesterase activity was measured by the ratte of produc...

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On the Growth Mechanism of Root Hairs

Cited by 18 publications

References 30 publications

Pectin and the role of the physical properties of the cell wall in pollen tube growth of Solanum chacoense

Pectin and the role of the physical properties of the cell wall in pollen tube growth of Solanum chacoense

The Essential Role of Calcium Ion in Pollen Germination and Pollen Tube Growth

Indoleacetic Acid and the Synthesis of Glucanases and Pectic Enzymes

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