Polar transport in plants mediated by membrane transporters: focus on mechanisms of polar auxin transport

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.

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

Functional Plant Biology ◽

10.1071/pp9770321 ◽

1977 ◽

Vol 4 (3) ◽

pp. 321 ◽

Cited By ~ 8

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.

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Cytokinins and polar transport of auxin in axillary pea buds

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis ◽

10.11118/actaun201058040079 ◽

2010 ◽

Vol 58 (4) ◽

pp. 79-88 ◽

Cited By ~ 13

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.

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

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.1992.020 ◽

2014 ◽

Vol 61 (2) ◽

pp. 221-230 ◽

Cited By ~ 1

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.

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Faculty Opinions recommendation of Regulation of phyllotaxis by polar auxin transport.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1005259.200927 ◽

2003 ◽

Author(s):

Rüdiger Simon

Keyword(s):

Auxin Transport ◽

Polar Auxin Transport

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Faculty Opinions recommendation of Phloem-transported cytokinin regulates polar auxin transport and maintains vascular pattern in the root meristem.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.13276996.14635106 ◽

2011 ◽

Author(s):

Robert Sablowski

Keyword(s):

Auxin Transport ◽

Root Meristem ◽

Polar Auxin Transport ◽

Vascular Pattern

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Faculty Opinions recommendation of Arabidopsis ROOT UVB SENSITIVE2/WEAK AUXIN RESPONSE1 is required for polar auxin transport.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.5108957.5044055 ◽

2010 ◽

Author(s):

Hanjo Hellmann

Keyword(s):

Auxin Transport ◽

Polar Auxin Transport ◽

Arabidopsis Root

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Membrane Sterol Composition in Arabidopsis thaliana Affects Root Elongation via Auxin Biosynthesis

International Journal of Molecular Sciences ◽

10.3390/ijms22010437 ◽

2021 ◽

Vol 22 (1) ◽

pp. 437

Author(s):

Meng Wang ◽

Panpan Li ◽

Yao Ma ◽

Xiang Nie ◽

Markus Grebe ◽

...

Keyword(s):

Root Elongation ◽

Auxin Transport ◽

Sterol Composition ◽

Polar Auxin Transport ◽

Sterol Biosynthesis ◽

Auxin Biosynthesis ◽

Root Tip ◽

Auxin Signaling ◽

Auxin Response ◽

Short Root

Plant membrane sterol composition has been reported to affect growth and gravitropism via polar auxin transport and auxin signaling. However, as to whether sterols influence auxin biosynthesis has received little attention. Here, by using the sterol biosynthesis mutant cyclopropylsterol isomerase1-1 (cpi1-1) and sterol application, we reveal that cycloeucalenol, a CPI1 substrate, and sitosterol, an end-product of sterol biosynthesis, antagonistically affect auxin biosynthesis. The short root phenotype of cpi1-1 was associated with a markedly enhanced auxin response in the root tip. Both were neither suppressed by mutations in polar auxin transport (PAT) proteins nor by treatment with a PAT inhibitor and responded to an auxin signaling inhibitor. However, expression of several auxin biosynthesis genes TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1 (TAA1) was upregulated in cpi1-1. Functionally, TAA1 mutation reduced the auxin response in cpi1-1 and partially rescued its short root phenotype. In support of this genetic evidence, application of cycloeucalenol upregulated expression of the auxin responsive reporter DR5:GUS (β-glucuronidase) and of several auxin biosynthesis genes, while sitosterol repressed their expression. Hence, our combined genetic, pharmacological, and sterol application studies reveal a hitherto unexplored sterol-dependent modulation of auxin biosynthesis during Arabidopsis root elongation.

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