Polar Movement of Gibberellic Acid through Young <i>Coleus</i> Petioles

Jacobs, William P.; Kaldewey, Harald

doi:10.1104/pp.45.4.539

Cited by 28 publications

(11 citation statements)

References 19 publications

(17 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After it was shown (7,8,11,16) that even the synthetic auxin-type herbicide 2, 4-D moved through excised shoot tissues with a polarity like that of the endogenous auxin IAA, other classes of hormones were tested. Just recently, GA. was found to move with a polarity very similar to IAA through Coleus petioles and with opposite polarity to IAA through corn root sections (12)(13)(14). Although early reports claimed polar movement of abscisic acid and a cytokinin (1, 4), the more quantitative later studies found sizeable movement in both directions, with no clear sign of polarity of these two classes of hormone (5,9,18 considered as confirmation of the hypothesis that in the intact plant thiamine was synthesized in the leaves and moved from there to the roots, which were unable to synthesize it but needed it for development.…”

mentioning

confidence: 99%

Polarity of Thiamine Movement through Tomato Petioles

Kruszewski¹,

Jacobs²

1974

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

Thiamine-"C moved through petiolar sections of Lycopersicon esculentum Mill. var. Michigan State Forcing with striking similarity in kinetics to auxins and gibberellic acid moving through similar sections of other green plants. Thiamine moved with strong basipetal polarity, at a velocity of 3 to 5 mm per hour, and emerged unchanged into the basal receiver agar block, judging by chromatography. This lends support to the hypothesis that polar movement is a property of several classes of plant hormones, rather than being restricted to the auxins (as previously believed).Multicellular plants show many polar phenomena during development and regeneration (e.g., regeneration of roots at the basal or "root" end of an excised stem section). Some of these phenomena have been explained as being manifestations of the movement of the plant hormones known as auxins, which have been known to move polarly since 1928 (10,19). After it was shown (7,8,11,16) that even the synthetic auxin-type herbicide 2, 4-D moved through excised shoot tissues with a polarity like that of the endogenous auxin IAA, other classes of hormones were tested. Just recently, GA. was found to move with a polarity very similar to IAA through Coleus petioles and with opposite polarity to IAA through corn root sections (12)(13)(14). Although early reports claimed polar movement of abscisic acid and a cytokinin (1, 4), the more quantitative later studies found sizeable movement in both directions, with no clear sign of polarity of these two classes of hormone (5,9,18 considered as confirmation of the hypothesis that in the intact plant thiamine was synthesized in the leaves and moved from there to the roots, which were unable to synthesize it but needed it for development. We could find no literature on the movement of thiamine through classical "transport sections." So that the results would be more useful for comparisons, we used the same general methods used earlier in this laboratory for studies of the movement of auxins, cytokinins, and GA3 (10-14, 16, 18). Sections 5.1 mm long were excised with a double-bladed cutter from the middle of petioles of leaves of tomato (Lycopersicon esculentum Mill. var. Michigan State Forcing). Tomato was used because of the numerous reports that its excised roots need thiamine for continued growth in culture. The excised petiolar sections were placed horizontally between donor and receiver blocks of 1.5% agar (see inset diagram of Fig. 1). Donor blocks contained thiamine, with stated specific radioactivity of 18.9 mc/mmole labeled with "4C in the thiazole 2 position, at a concentration of 15 uM. A donor block was placed against the apical ("leaf blade") end of the petiolar section when movement in the basipetal direction was being tested (as in inset diagram), and against the basal cut end (stem end) when acropetal movement was being tested. These transport systems were placed on glass slides in moist Petri dishes which were placed in a dark incubator at 26 to 27 C. After 2, 3, or 4 hr the receiver blocks were remo...

show abstract

mentioning

confidence: 99%

Polarity of Thiamine Movement through Tomato Petioles

Kruszewski¹,

Jacobs²

1974

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

show abstract

mentioning

confidence: 99%

“…Recently, plant hormones other than auxins have been demonstrated to move in a polar fashion through the plant tissues (18,20,21,26). Gibberellic acid which has been shown to move with basipetal polarity through sections cut from young petioles of the Princeton clone of Coleus blumei (18,20) is known to affect primary phloem fiber differentiation (9,34,36,37).In an attempt to understand the mechanism that determines and controls the polar differentiation of primary phloem fibers with sieve and vessel elements in the vascular bundles, a working hypothesis was set up as follows. Knowing that the polar movement of IAA through an organized tissue induces the differentia-' Supported in part by the Lady Davis Fellowship Trust.…”

mentioning

confidence: 99%

Role of Auxin and Gibberellin in Differentiation of Primary Phloem Fibers

Aloni

1979

Plant Physiol.

107

View full text Add to dashboard Cite

The hypothesis that auxin and gibberellic acid (GA3) control the differentiation of primary phloem fibers is confirmed for the stem of Coleus blumei Benth. Indoleacetic acid (IAA) alone sufficed to cause the differentiation of a few primary phloem fibers. In long term experiments auxin induced a considerable number of fibers in mature internodes. GA3 by itself did not exert any effect on fiber differentiation. Combinations of IAA with GA3 completely replaced the role of the leaves in primary phloem fiber differentiation qualitatively and quantitatively. Although the combined effect of the two growth hormones diminished considerably with increasing distance from the source of induction, auxin with GA3 or IAA alone induced fibers in a few internodes below the application site. When various combinations of both hormones were applied, high concentrations of IAA stimulated rapid differentiation of fibers with thick secondary walls, while high levels of GA3 resulted in long fibers with thin walls. The size of the primary phloem fibers correlated with the dimensions of the differentiating internode, thereby providing evidence that both growth regulators figure in the control of stem extension. High IAA/low GA3 concentrations have an inhibitory effect on internode elongation, whereas low IAA/high GA3 concentrations promote maximal stem elongation.In Coleus, the primary phloem fiber initials differentiate in the vascular bundles in the periphery of the primary sieve elements. The single nucleus of the fiber initial divides several times and cytokinesis occurs by the formation of septa (24,25). Primary phloem fiber differentiation is dependent on stimuli originating in the leaves (2, 5, 31). The stimuli for fiber differentiation flow in a strictly polar fashion from the leaves to the root (2). Leaves induce fiber differentiation in several internodes below them. Young Coleus leaves yield shorter fibers than those which differentiate under mature leaves, indicating that more than one stimulus is involved in the induction process (5).Some of the polar phenomena occurring during plant development and regeneration are attributable to the polar movement of auxins. Recently, plant hormones other than auxins have been demonstrated to move in a polar fashion through the plant tissues (18,20,21,26). Gibberellic acid which has been shown to move with basipetal polarity through sections cut from young petioles of the Princeton clone of Coleus blumei (18,20) is known to affect primary phloem fiber differentiation (9,34,36,37).In an attempt to understand the mechanism that determines and controls the polar differentiation of primary phloem fibers with sieve and vessel elements in the vascular bundles, a working hypothesis was set up as follows. Knowing that the polar movement of IAA through an organized tissue induces the differentia-' Supported in part by the Lady Davis Fellowship Trust. tion of a vascular bundle which consists of sieve tubes or sieve tubes and vessels (15,23,38), it was hypothesized that when an additional p...

show abstract

“…These results agree with those of Jacobs (6), who demonstrated kinetin movement through Coleus petiole sections to be nonpolar at 1.1 mm/hr. Although Jacobs and Kaldewey (7) have reported experiments which suggest basipetally polar movement of GA3 in Coleus petiole sections, the majority of papers examining GA3 transport in tissue sections report nonpolar movement (1,10). Phillips and Hartung (13) were unable to detect activity in receiver blocks after 16-hr transport of GA, through 6-to 8-mm Phaseolus coccineus stem sections.…”

Section: Discussionmentioning

confidence: 99%

“…This report relates results of experiments examining the capacity of cotton cotyledonary petioles to transport kinetin and GA3 prior to, during, and after exposure to such conditions. MATERIALS AND METHODS Plant culture and procedures for determination of transport capacity have been previously described in detail (2,3 [1,7,12,18-14C] GA3 (1.7 mCi/mmol, Amersham/Searle Corp., Amersham, England) were placed atop each section for 0.5 hr after which they were replaced with agar "chase" blocks containing nonlabeled 10 ,lM kinetin or 10 ,UM GA3, respectively. The relatively high concentration oflabeled GA3 was necessary to obtain sufficient radioactivity in the tissue sections.…”

mentioning

confidence: 99%

Movement of Kinetin and Gibberellic Acid in Leaf Petioles during Water Stress-induced Abscission in Cotton

1979

View full text Add to dashboard Cite

Movement of I14Clkinetin and I'4Clgibberelic acid was examined in cotton (Gossypium hirsutum L.) cotyledonary petiole sections independent of label uptake or exit from the tissue. Sections 20 mimeters in length were taken from well watered, stressed, and poststressed plants. Transport capacity was determined using a pulse-chase technique. Movement of both kinetin and gibberellic acid was found to be nonpolar with a velocity of 1 millimeter per hour or less, suggesting passive diffusion. Neither water stress nor anaerobic conditions during transport of labeled material affected the transport capacity of the petioles.Results suggested strong kinetin binding but weak gibberellic acid binding in the tissue sections. Apparent binding of both growth regulators was unaltered by the experimental conditions. Movement of these two growth regulators within cotton cotyledonary petioles plays a minor role in the stress-induced, foliar abscission process.Foliar abscission resulting from water deficits has recently been shown to be correlated with a decrease in the auxin transport capacity of subtending petioles (3). A clear understanding of the complex interactions of other hormones within the plant during the abscission process is imperative if we are to elucidate mechanisms of abscission induction. ABA levels clearly rise during periods of water stress (18,19), but the changes in extracted ABA from cotton cotyledons do not appear to correlate with induced abscission of cotyledonary leaves (2). Nor does ABA appear to be transported in petiolar segments either prior to, during, or after relief of water stress (2). Although two other major classes of plant hormones, cytokinins and GA3, have been studied in relation to leaf abscission (11, 15, 16) [1,7,12,18-14C] GA3 (1.7 mCi/mmol, Amersham/Searle Corp., Amersham, England) were placed atop each section for 0.5 hr after which they were replaced with agar "chase" blocks containing nonlabeled 10 ,lM kinetin or 10 ,UM GA3, respectively. The relatively high concentration oflabeled GA3 was necessary to obtain sufficient radioactivity in the tissue sections. Half of the sections were allowed to continue transport with chase blocks in place for an additional 0.5 hr and the other half for 2.5 hr. There was no apparent rehydration of stressed petioles throughout the transport experiments. Each 20-mm section was then cut into 10 segments 2 mm in length each of which was pooled with corresponding segments, placed into scintillation vials (total of 10 segments/vial) containing 15 ml of a dioxane-naphthalene-PPO-based scintillation fluid, and shaken for 24 hr at room temperature.

show abstract

Polar Movement of Gibberellic Acid through Young Coleus Petioles

Cited by 28 publications

References 19 publications

Polarity of Thiamine Movement through Tomato Petioles

Polarity of Thiamine Movement through Tomato Petioles

Role of Auxin and Gibberellin in Differentiation of Primary Phloem Fibers

Movement of Kinetin and Gibberellic Acid in Leaf Petioles during Water Stress-induced Abscission in Cotton

Contact Info

Product

Resources

About