scholarly journals The integration of plant behaviour. III.- The effect of gravity on the growth of roots

1931 ◽  
Vol 108 (758) ◽  
pp. 360-365 ◽  
Keyword(s):  
Avena Sativa ◽  
Growth Substance ◽  
Horizontal Axis ◽  
Horizontal Position ◽  
Growth Substances ◽  
Plant Organs ◽  
Rate Of Growth ◽  
Interesting Discussion ◽  
Plant Behaviour

The question whether the transverse stimulus of gravity affects the rate of growth of various parts of plants has been often investigated, but with results that are in part very contradictory. For a convenient discussion of the results obtained up to 1925, reference may be made to a paper by Gradmann (1925, p. 237). More recently Dolk (1929) has obtained automatic records of the growth of Avena coleeptiles when rotated on the horizontal axis of the clinostat and when placed vertical. His records, which seem quite free from objection, show so uniform a rate of growth that it must be concluded that in these plant organs in these conditions the change from the vertical to the horizontal position, or vice versa , makes no difference to the rate of growth. Cholodny also has obtained evidence that in hypocotyls of Lupinus and Helianthus (1929) and in coleoptiles of Avena sativa (1930), the rate of growth id not affected by their position in relation to gravity. Dolk and Cholodny interpret these results in favour of the Cholodny-Went theory of geotropism, according to which the geotropic curvatures of roots and coleoptiles are brought about by growth-substances continually secreted by the tips, which become re-distributed between the upper and lower sides under the stimulus of gravity, though their total quantity is supposed not to be changed. Now the writers regard this theory favourably, but none the less it appears to them that even if this re-distribution does takes place, and even if it suffices to account for the geotropic curvatures, it remains possible that in some that organs at least the transverse stimulus of gravity may also alter the total quantity of growth-substance. This point has been emphasised by Gradmann in an interesting discussion (1930, p. 596). Actually it is well known that in the nodes of grasses the transverse stimulus of gravity does alter the rate of growth. For nodes that have completed their growth may start growing again if placed horizontal.

Nonpolar movement of N6-benzyladenine-14C in coleoptile, stem, petiole, and floral organ sections

1973 ◽  
Vol 51 (11) ◽  
pp. 2079-2083 ◽  
Author(s):  
James L. Koevenig
Keyword(s):  
Avena Sativa ◽  
Time Course ◽  
Floral Organ ◽  
Scintillation Counting ◽  
Passive Diffusion ◽  
Plant Organs ◽  
Polar Movement ◽  
Metabolic Difference

Movement of N6-benzyladenine-methylene-14C in Avena sativa coleoptiles, Colens blumei stems and petioles, and Cleome hassleriana stamen filaments, gynophores, and pedicels was studied by suspending sections horizontally between donor and receiver agar cylinders and determining radioactivity in receivers by scintillation counting. No polar movement was found in any of the plant organs. In time-course experiments using oat coleoptiles, the amount of radioactivity in receivers continued to increase for 24 h and the velocity was 1.5-2 mm/h, suggesting movement by passive diffusion. More radioactivity moved through stamen filaments and gynophore sections from mature expanded flowers than through those from young buds, apparently as a result of larger uptake and exit areas in expanded flowers. A significantly greater acropetal and basipetal movement through young pedicels is not due to area differences and probably results from a metabolic difference.

scholarly journals The integration of plant behaviour V—Growth substance and traumatic curvature of the root

1935 ◽  
Vol 117 (803) ◽  
pp. 92-119 ◽  
Keyword(s):  
Positive Curvature ◽  
Inhibitory Effect ◽  
Growth Substance ◽  
The Other ◽  
Root Tip ◽  
Lower Side ◽  
Mode Of Operation ◽  
The One ◽  
Lateral Wound ◽  
Plant Behaviour

The manner of response of the root to injury is well known. A lateral wound made within 1 mm or 2 mm of the extreme tip gives rise to a negative curvature: the root curves away from the wound. A similar injury made elsewhere in the growing region evokes a positive curvature; the root curves towards the wound. The curvatures are manifestly growth curvatures. Like those induced by gravity, traumatic curvatures are the consequence of unequal growth of opposite sides of the region of elongation. In the one case they are undoubtedly brought about by the stimulus of gravity; and in the other they are supposed also to owe their origin to a stimulus, a wound stimulus. But, whereas something at all events is known of the way in which the stimulus of gravity acts on the root, the mode of operation of the wound stimulus—if stimulus there be— remains obscure. The Went-Cholodny hypothesis of geotropism which is supported by Cholodny’s experiments (1924, 1926), those of the authors in collaboration with R. Snow (1931), of Boysen-Jensen (1933, a, b ), and others (Snow, 1932), attributes to growth substance contained in the root an essential part in geotropic curvature. It holds that growth substance which inhibits the growth of the root is a normal secretion of the root tip. Produced continuously by the tip, it passes upwards by straight paths and reaches all parts of the region of elongation. Although in the passage through the elongating region the concentration falls off progressively, the dis­tribution of growth substance at any given level is uniform and therefore, the inhibitory effect being equal on all sides, the unstimulated root continues to follow a straight downward path. When, however, the root is exposed to the stimulus of gravity the uniformity of distribution of growth substance is disturbed; more is found to occur on the lower than on the upper side of the tip and the inequality of distribution is held to be due to a passage downward from the one side to the other. Since the lower side of the tip now contains more, and since growth substance travels from tip to elongating region by straight paths, the lower side of the elongating region comes also to contain more than the upper side; the upper side grows faster than the lower and the root curves downward.

EFFECT OF ALBUGO CANDIDA (PERS. EX CHEV.) KUNTZE ON GROWTH SUBSTANCES IN BRASSICA NAPUS L.

1962 ◽  
Vol 40 (1) ◽  
pp. 53-59 ◽  
Author(s):  
B. I. S. Srivastava ◽  
Michael Shaw ◽  
T. C. Vanterpool
Keyword(s):  
Brassica Napus ◽  
Total Activity ◽  
Growth Substance ◽  
Growth Substances ◽  
Fresh Weight ◽  
Good Source ◽  
Brassica Napus L ◽  
Albugo Candida ◽  
Solvent Systems ◽  
Hydrolysis Of

IAA, IAN, accelerator α, and an ether-insoluble growth substance (designated as 'A') were found in alcohol extracts of healthy inflorescences of Brassica napus L. and in smaller amounts in the malformed, parasitized inflorescences produced by plants infected with Albugo Candida (Pers. ex Chev.) Kuntze. The total activity of diseased extracts (≡ 915 μg IAA/kg fresh weight) was only 61% of that of healthy ones. IAN accounted for approximately 86% of the total activity in both extracts. Brassica is thus a good source of IAN. Both IAA and IAN were identified by their chromogenic reactions, ultraviolet spectra, and Rf values in two solvent systems. Alkaline hydrolysis of 'A' produced an ether-soluble, Ehrlich-positive spot with the same Rf value as IAA. The results are discussed briefly.

Effects of growth substances on the protoplasmic drought tolerance of leaf cells of the resurrection grass, Sporobolus stapfianus

2001 ◽  
Vol 28 (11) ◽  
pp. 1115 ◽  
Author(s):  
Hamid R. Ghasempour ◽  
Esther M. Anderson ◽  
Donald F. Gaff
Keyword(s):  
Drought Tolerance ◽  
Desiccation Tolerance ◽  
Free Cell ◽  
Growth Substance ◽  
Cell Suspensions ◽  
Individual Plant ◽  
Severe Drought ◽  
Growth Substances ◽  
Sporobolus Stapfianus ◽  
Suspended Cells

Hydrated leaves of the resurrection grass Sporobolus stapfianus Gandoger are not desiccation tolerant, but moderate to severe drought stress can induce their desiccation tolerance while the leaves remain attached to drying intact plants. Free-cell suspensions prepared from fully turgid leaves of S. stapfianus were also found to be desiccation-sensitive. In this study a sensitive assay was developed to determine the effect of exogenous substances on the protoplasmic drought tolerance (PDT) of cell suspensions. Suspended cells were incubated with a wide variety of individual plant growth substances over a range of concentrations. After the incubation, the protoplasmic drought tolerance at each concentration of each substance was determined osmotically. Brassinolide (BR) and methyljasmonic acid (MJA), applied separately, gave the greatest effect — each improved PDT by approximately 6 MPa, compared with controls incubated without growth substances. Exogenous abscisic acid (ABA) improved the PDT of S. stapfianus only slightly (about 1 MPa). Salicylic acid (SA), 1-aminocyclopropane–1-carboxylic acid (ACC), ethephon, gibberellic acid (GA), kinetin (KN) andN 6 -(2-isopentyl)adenine (2ip) each improved PDT by ca 1.5 MPa. Indoleacetic acid (IAA) had no effect, and zeatin (ZN) had a deleterious effect on PDT. Incubation of suspended cells in combinations of two growth substances (MJA with ABA, ACC, BR, GA, IAA or KN; BR with ABA) produced no evidence of synergism, or in most cases, even of additive effects of the tested substances. ABA, BR and MJA (applied separately) stimulated the synthesis of numerous specific proteins. Each growth substance stimulated the synthesis of differing proteins, with four exceptions. This investigation raises the possibility that BR and MJA may play a role in a chain of events which leads eventually to the induction of desiccation tolerance in leaves of S. stapfianus. The effects on cell PDT observed in this study, while large, were insufficient to account for the remarkable improvement observed in the PDT of S. stapfianus leaves attached to drying plants.

Regulation of seed dormancy m Elaeagnus umbellata by endogenous growth substances

1975 ◽  
Vol 53 (20) ◽  
pp. 2303-2311 ◽  
Author(s):  
D. F. Hamilton ◽  
P. L. Carpenter
Keyword(s):  
Biological Activity ◽  
Low Temperature ◽  
Seed Dormancy ◽  
Growth Substance ◽  
The Other ◽  
Lettuce Seed ◽  
Growth Substances ◽  
Dormant Seed ◽  
Elaeagnus Umbellata ◽  
Growth Inhibiting

The growth-substance content of fruits of Elaeagnus umbellata was examined as part of an investigation of the regulation of seed dormancy of this species. Extracts of dormant seed fractions were separated chromatographically in various solvents and biological activity was determined in a lettuce-seed and a cucumber-seed bioassay. The bioassays showed that a growth-inhibiting substance with an Rf value similar to coumarin was present throughout the dormant seed. Fluorescence also showed that the inhibitor closely resembled coumarin.Activity of the inhibitor did not decrease during 90 days at 5 °C, and evidence indicates it may be physiologically active in preventing germination. On the other hand, germination-promoting substances that may counteract the effect of the inhibitor were found to be produced in the embryo during low-temperature afterripening.

scholarly journals Untersuchungen über die Bindung pflanzlicher Wuchsstoffe an verschiedene Komponenten des Chromatins in vitro. I. Bindung an DNS / Investigations Upon the Binding of Plant Growth Substances to Several Components of the Chromatin in vitro. I. Binding to DNA

1971 ◽  
Vol 26 (6) ◽  
pp. 607-612 ◽  
Author(s):  
Günter Fellenberg
Keyword(s):  
Hydrogen Bonds ◽  
Absorption Maximum ◽  
Double Helix ◽  
Specific Effect ◽  
Growth Substance ◽  
Growth Substances ◽  
Plant Growth Substances ◽  
The Stability ◽  
Dna Double Helix

At pH 9,5 the DNA absorption maximum at 190 nm was shifted to 212 nm. This absorption maximum showed a bathochrome effect in the presence of IAA, GA and KI. The amplitude of this maximum was reduced at the same time. By addition of urea (0.1 —2.0 moles/l) the bathochrome effect, induced by the growth substances, was completely reversed, whereas application of NaCl (0.1 — 2.0 moles/l) did not affect the bathochrome movement of this DNA maximum. At pH 6.0 in the presence of 0.9% NaCl this DNA maximum did not show any visible bathochrome movement in the presence of the growth substances investigated. The DNA maximum at 260 nm did not show any alteration in the presence of growth substances.The thermal denaturation of DNA-complexes with IAA and GA showed, that with increasing concentration of these growth substances, the Tm-value of the DNA was reduced. On the other hand, KI increased the Tm-point of DNA. By biphasic melting at 260 nm and 280 nm no specific effect of the investigated growth substances on the stability of the A — T or G—C pairs was detected.Tryptophan and β-NAA closely related in structure to the auxins IAA and α-NAA did not reduce the Tm-value of DNA.At pH < 7 IAA, GA and KI did not show any detectable influence on the Tm-value of DNA.The data presented show that at a pH > 7 IAA, GA and KI are obviously bound to DNA by hydrogen bonds. There is evidence that these bonds are very unstable. Nevertheless, IAA and GA can loosen part of the hydrogen bonds of DNA double helix while KI cannot. Possible consequences of these growth substance effects on DNA are discussed.

scholarly journals Roles of plant growth substance in callus induction of Achyranthes bidentata

2016 ◽  
Vol 6 ◽  
Author(s):  
Hongying Duan ◽  
Weikai Ding ◽  
Jianying Song ◽  
Jiaming Xu ◽  
Huina Wang ◽  
...  
Keyword(s):  
Plant Growth ◽  
Callus Induction ◽  
Growth Substance ◽  
Optimum Combination ◽  
Dichlorophenoxyacetic Acid ◽  
Growth Substances ◽  
Plant Growth Substance ◽  
Achyranthes Bidentata ◽  
Plant Growth Substances ◽  
2,4 Dichlorophenoxyacetic Acid

<p>    <strong>In this research, callus from leaves, petioles and stems of <em>Achyranthes bidentata</em> was evidently initiated by plant growth substance, in which 2,4-dichlorophenoxyacetic acid (2,4-D) was very important to callus induction, but effects of other plant growth substances were various, and the optimum combination of plant growth substances for callus induction from leaves, petioles and stems was respectively obtained. Compared with callus induction from leaves and petioles, callus induction from stems was easier, and the higher induction rate and bigger mass of callus from stems were obtained. This study showed that the dedifferentiation capacity</strong><strong> of various explants from </strong><strong><em>Achyranthes bidentata</em></strong><strong> was obviously different, and effects of plant growth substance on callus induction from various explants of <em>Achyranthes bidentata</em> were significantly diverse.</strong><strong></strong></p>

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