The Mechanism of Transmembrane Auxin Transport and Its Relation to the Chemiosmotic Hypothesis of the Polar Transport of Auxin

1980 ◽  
pp. 50-60 ◽  
Author(s):  
P. H. Rubery
Keyword(s):  
Auxin Transport ◽  
Polar Transport ◽  
Chemiosmotic Hypothesis

scholarly journals Auxin minimum triggers the developmental switch from cell division to cell differentiation in the Arabidopsis root

2017 ◽  
Vol 114 (36) ◽  
pp. E7641-E7649 ◽  
Author(s):  
Riccardo Di Mambro ◽  
Micol De Ruvo ◽  
Elena Pacifici ◽  
Elena Salvi ◽  
Rosangela Sozzani ◽  
...  
Keyword(s):  
Cell Division ◽  
Auxin Transport ◽  
Positional Information ◽  
Polar Auxin Transport ◽  
Arabidopsis Root ◽  
Polar Transport ◽  
Stringent Control ◽  
Auxin Polar Transport ◽  
Multicellular Organisms ◽  
Developmental Switch

In multicellular organisms, a stringent control of the transition between cell division and differentiation is crucial for correct tissue and organ development. In the Arabidopsis root, the boundary between dividing and differentiating cells is positioned by the antagonistic interaction of the hormones auxin and cytokinin. Cytokinin affects polar auxin transport, but how this impacts the positional information required to establish this tissue boundary, is still unknown. By combining computational modeling with molecular genetics, we show that boundary formation is dependent on cytokinin’s control on auxin polar transport and degradation. The regulation of both processes shapes the auxin profile in a well-defined auxin minimum. This auxin minimum positions the boundary between dividing and differentiating cells, acting as a trigger for this developmental transition, thus controlling meristem size.

Auxinlike Activity and Metabolism of Mefluidide in Corn (Zea mays) and Soybean (Glycine max) Tissue

Weed Science ◽  
1985 ◽  
Vol 33 (4) ◽  
pp. 452-456 ◽  
Author(s):  
Scott Glenn ◽  
Charles E. Rieck
Keyword(s):  
Zea Mays ◽  
Glycine Max ◽  
Phenyl Ring ◽  
Auxin Transport ◽  
Indoleacetic Acid ◽  
Meristematic Tissue ◽  
Polar Transport ◽  
M 10 ◽  
Coleoptile Elongation

Mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl) sulfonyl] amino] phenyl] acetamide} was evaluated for effects on corn [Zea mays(L.) ‘Pioneer 3535’] coleoptile elongation. Mefluidide at 10-8M, 10-7M, and 10-6M stimulated elongation approximately equal to growth stimulations with 10-6M indoleacetic acid (IAA). Polar transport of14C-IAA from donor agar blocks through corn coleoptiles and into receiver agar blocks after 12 h was increased 246% by 10-4M mefluidide and inhibited 82% by 10-3M mefluidide. Mefluidide-related chemicals (10-4M) lacking a trifluoromethyl-sulfonyl-amino chain at the 1-position of the phenyl ring did not alter14C-IAA transport. IAA transport was increased 97% when the acetamide chain at the 5-position was absent and 255% when the methyl in the 4-position was absent, and it decreased 65% when the methyl at the 2-position was absent. Polar transport of14C-IAA through soybean [Glycine max(L.) Merr. ‘Williams’] hypocotyls was not altered by 10-4M mefluidide; however, 10-3M mefluidide increased IAA transport 116%. After 6 h, corn coleoptiles metabolized 14% of the mefluidide absorbed and soybean metabolized 54% of the mefluidide absorbed from14C-mefluidide solutions (10-6M). Differences in the rate of metabolism of mefluidide in meristematic tissue of corn and soybean may explain differences in mefluidide effects on auxin transport in corn and soybean.

scholarly journals Oscillation of stem polarity expression in transport of natural auxin of pine cambium

2014 ◽  
Vol 57 (1) ◽  
pp. 165-176
Author(s):  
Tomasz J. Wodzicki ◽  
Alina B. Wodzicki ◽  
Claud L. Brown
Keyword(s):  
Pinus Taeda ◽  
Short Distance ◽  
Auxin Transport ◽  
Phase Synchronization ◽  
Pinus Silvestris ◽  
Polar Transport ◽  
Direct Involvement ◽  
Simultaneous Measurements ◽  
Cambial Zone ◽  
Cambial Cells

Simultaneous measurements of acropetal and basipetal efflux of natural auxin from the cambial region of a series of successive sections from <em>Pinus silvestris</em> stems revealed an unknown until now variation of polarity expression in the transport of auxin, which occurs in short cycles along the stem. It is suggested that the direction of phase synchronization of this oscillation between the neighboring cambial cells determines the fronts of the auxin waves. Modulations of the auxin-wave caused by apical application of synthetic IAA were shown to depend upon changes in the polarity expression in respect to natural auxin transport. Some evidence of a direct involvement of the exogenous auxin in the mechanism responsible for oscillations of the polarity expression was also obtained in experiments, in which <sup>14</sup>C-IAA was applied directly into the phloem of living trees of <em>Pinus taeda</em> L. Transport of labelled auxin was very slow however, and its direct involvement in polar transport (the oscillation of which was measured) extended only for a short distance from the place of aplication. Simultaneously, the natural auxin wave measured by bioassays extended to further distances. The results corroborate the hypothesis that oscillations of the polarity expression responsible for generation of the auxin wave in cambium depend primarily upon a system autonomous to cells of the cambial region, independent of the direct contribution of the molecules of auxin produced at distant sources. On the other hand, such external to cambium sources of auxin modulate the auxin-wave parameters affecting the system responsible for expression of the polarity in the regions close to their synthesis. These modulations are than propagated in the cambial zone.

Auxin Transport Inhibitors. II. 2-(1-Pyrenol)Benzoic Acid, a Potent Inhibitor of Polar Auxin Transport

1977 ◽  
Vol 4 (3) ◽  
pp. 321 ◽  
Author(s):  
GF Katekar ◽  
AE Geissler
Keyword(s):  
Benzoic Acid ◽  
Auxin Transport ◽  
Indoleacetic Acid ◽  
Potent Inhibitor ◽  
Polar Auxin Transport ◽  
Active Inhibitor ◽  
Polar Transport ◽  
Highly Active ◽  
Transport Inhibitors ◽  
Auxin Transport Inhibitors

2-(1-Pyrenoyl)benzoic acid is shown to be a highly active inhibitor of auxin transport by its ability to prevent the polar transport of indoleacetic acid in bean petioles. It is comparable in activity to other known auxin transport inhibitors, and also affects apical dominance and the geotropic and phototropic responses.

scholarly journals Cytokinins and polar transport of auxin in axillary pea buds

2010 ◽  
Vol 58 (4) ◽  
pp. 79-88 ◽  
Author(s):  
Petr Kalousek ◽  
Dagmar Buchtová ◽  
Jozef Balla ◽  
Vilém Reinöhl ◽  
Stanislav Procházka
Keyword(s):  
Apical Dominance ◽  
Auxin Transport ◽  
Polar Auxin Transport ◽  
Axillary Buds ◽  
Polar Transport ◽  
Exogenous Application ◽  
Intact Plants ◽  
Key Factor ◽  
Basal Pole ◽  
Auxin Carrier

The influence of cytokinin on auxin transport during release of axillary buds from apical dominance was studied. Expression of auxin-carrier coding genes PsAUX1 (AUXIN RESISTANT 1) and PsPIN1 (PIN-FORMED 1) was explored in axillary buds of the 2nd node of 7-day pea plants (Pisum sativum L.) cv. Vladan after decapitation or after exogenous application of benzyladenine (6-benzylaminopurine) onto axillary buds of intact plants. Localization of the PsPIN1 protein, the key factor for polar transport of auxin in axillary buds, was visualised by immunohistochemistry. After exogenous application of cytokinin the expression of PsAUX1 and PsPIN1 rapidly increased with a simultaneous rapid decrease in PsDRM1 and PsAD1 expression – genes related to bud dormancy. The same changes in expression were observed after decapitation, however they were markedly slower. The PsPIN1 auxin efflux carrier in the inhibited axillary buds of intact plants was localised in a non-polar manner. After exogenous application of cytokinin gradual polarisation of the PsPIN1 protein occurred on the basal pole of polar auxin transport competent cells. Despite the fact that direct auxin application to buds of intact plants led to an increase in PsAUX1 and PsPIN1 expression, the buds remained dormant (non-growing) what was accompanied by persistent expression of the dormancy markers PsDRM1 and PsAD1. The results indicate a possible effect of cytokinins on biosynthesis, and/or transport of auxin in axillary buds and they highlight the importance of auxin-cytokinin crosstalk in the regulation of bud outgrowth after breaking of apical dominance.

scholarly journals Endogenous oscillations of electric potential difference in the cambial region of the pine stem. II. Possible involvement of the oscillations in xylogenesis

2014 ◽  
Vol 61 (2) ◽  
pp. 221-230 ◽  
Author(s):  
Wojciech Kurek
Keyword(s):  
Electric Potential ◽  
Auxin Transport ◽  
Cambial Activity ◽  
Polar Auxin Transport ◽  
Potential Difference ◽  
Wood Production ◽  
Polar Transport ◽  
Tissue Block ◽  
Late Wood ◽  
Electric Potential Difference

Direct and indirect interrelations between xylogenic processes and the endogenous electric potential difference (PD) oscillations generated in the cambial region of isolated tissue blocks from pine trunks were investigated. The frequency of transient PD changes varied during the season and displayed three minima which were concurrent with periods of initiation and termination of cambial activity and with the time of transition from early- to late-wood production. The oscillations were damped by TIBA - an inhibitor of polar auxin transport and stimulated by IAA, but only when the hormone was supplied to the apical end of the tissue block. This suggests that the polar transport of auxin may be involved in generation of the transient PD changes. Results of 2-channel recordings in one tissue block suggest that a part of the recorded oscillations (10-25 %) exhibit coordination in space and time: a wave-like pattern along the trunk axis is created by PD changes. The pattern might be a physical carrier of information coordinating processes of growth and differentiation in distant parts of the tree.

Sign in / Sign up

Export Citation Format

Share Document