| 1. |
- Boutté, Yohann, et al.
(författare)
-
Mechanisms of auxin-dependent cell and tissue polarity
- 2007
-
Ingår i: Current opinion in plant biology. - : Elsevier. - 1369-5266 .- 1879-0356. ; 10:6, s. 616-623
-
Tidskriftsartikel (refereegranskat)abstract
- The establishment of cellular asymmetries and their coordination within the tissue layer are fundamental to the development of multicellular organisms. In plants, the induction and coordination of cell polarity have classically been attributed to involve the hormone auxin and its flow. However, the underlying mechanisms have only recently been addressed at the molecular level. We review progress on the characterisation of the auxin influx and efflux carrier properties of specific plasma membrane proteins, mechanisms underlying their delivery to and internalisation from the plasma membrane, their endocytic transport and degradation. We discuss mechanisms of auxin gradient, transport and response action during the coordination of polarity, along with the downstream involvement of Rho-of-plant small GTPases during the execution of cell polarity.
|
|
| 2. |
- Fischer, Urs, et al.
(författare)
-
Planar polarity of root hair positioning in Arabidopsis
- 2007
-
Ingår i: Biochemical Society Transactions. - 0300-5127 .- 1470-8752. ; 35:Pt 1, s. 149-151
-
Tidskriftsartikel (refereegranskat)abstract
- The co-ordinated polarity of cells within the plane of a single tissue layer (planar polarity) is intensively studied in animal epithelia but has only recently been systematically analysed in plants. The polar positioning of hairs in the root epidermis of Arabidopsis thaliana provides an easily accessible system for the functional dissection of a plant-specific planar polarity. Recently, mutants originally isolated in genetic screens for defects in root hair morphogenesis and changes in the sensitivity to or the production of the plant hormones auxin and ethylene have identified players that contribute to polar root hair placement. Here, we summarize and discuss recent progress in research on polar root hair positioning from studies in Arabidopsis.
|
|
| 3. |
- Fischer, Urs, et al.
(författare)
-
Vectorial information for Arabidopsis planar polarity is mediated by combined AUX1, EIN2, and GNOM activity
- 2006
-
Ingår i: Current Biology. - : Elsevier. - 0960-9822 .- 1879-0445. ; 16:21, s. 2143-2149
-
Tidskriftsartikel (refereegranskat)abstract
- Cell polarity is commonly coordinated within the plane of a single tissue layer (planar polarity), and hair positioning has been exploited as a simple marker for planar polarization of animal epithelia . The root epidermis of the plant Arabidopsis similarly reveals planar polarity of hair localization close to root tip-oriented (basal) ends of hair-forming cells . Hair position is directed toward a concentration maximum of the hormone auxin in the root tip , but mechanisms driving this plant-specific planar polarity remain elusive. Here, we report that combinatorial action of the auxin influx carrier AUX1, ETHYLENE-INSENSITIVE2 (EIN2) , and GNOM genes mediates the vector for coordinate hair positioning. In aux1;ein2;gnom eb triple mutant roots, hairs display axial (apical or basal) instead of coordinate polar (basal) position, and recruitment of Rho-of-Plant (ROP) GTPases to the hair initiation site reveals the same polar-to-axial switch. The auxin concentration gradient is virtually abolished in aux1;ein2;gnom eb roots, where locally applied auxin can coordinate hair positioning. Moreover, auxin overproduction in sectors of wild-type roots enhances planar ROP and hair polarity over long and short distances. Hence, auxin may provide vectorial information for planar polarity that requires combinatorial AUX1, EIN2, and GNOM activity upstream of ROP positioning.
|
|
| 4. |
- Ikeda, Yoshihisa, et al.
(författare)
-
Local auxin biosynthesis modulates gradient-directed planar polarity in Arabidopsis
- 2009
-
Ingår i: Nature Cell Biology. - : Nature Publishing Group. - 1465-7392 .- 1476-4679. ; 11:6, s. 731-738
-
Tidskriftsartikel (refereegranskat)abstract
- The coordination of cell polarity within the plane of a single tissue layer (planar polarity) is a crucial task during development of multicellular organisms. Mechanisms underlying establishment of planar polarity, however, differ substantially between plants and animals. In Arabidopsis thaliana, planar polarity of root-hair positioning along epidermal cells is coordinated towards maximum concentration of an auxin gradient in the root tip. This gradient has been hypothesized to be sink-driven and computational modelling suggests that auxin efflux carrier activity may be sufficient to generate the gradient in the absence of auxin biosynthesis in the root. Here, we demonstrate that the Raf-like kinase CONSTITUTIVE TRIPLE RESPONSE1 (CTR1; Refs 8, 9) acts as a concentration-dependent repressor of a biosynthesis-dependent auxin gradient that modulates planar polarity in the root tip. We analysed auxin biosynthesis and concentration gradients in a variety of root-hair-position mutants affected in CTR1 activity, auxin biosynthesis and transport. Our results reveal that planar polarity relies on influx- and efflux-carrier-mediated auxin redistribution from a local biosynthesis maximum. Thus, a local source of auxin biosynthesis contributes to gradient homeostasis during long-range coordination of cellular morphogenesis.
|
|
| 5. |
- Kiefer, Christian S., et al.
(författare)
-
Arabidopsis AIP1-2 restricted by WER-mediated patterning modulates planar polarity
- 2015
-
Ingår i: Development. - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 142:1, s. 151-161
-
Tidskriftsartikel (refereegranskat)abstract
- The coordination of cell polarity within the plane of the tissue layer (planar polarity) is crucial for the development of diverse multicellular organisms. Small Rac/Rho-family GTPases and the actin cytoskeleton contribute to planar polarity formation at sites of polarity establishment in animals and plants. Yet, upstream pathways coordinating planar polarity differ strikingly between kingdoms. In the root of Arabidopsis thaliana, a concentration gradient of the phytohormone auxin coordinates polar recruitment of Rho-of-plant (ROP) to sites of polar epidermal hair initiation. However, little is known about cytoskeletal components and interactions that contribute to this planar polarity or about their relation to the patterning machinery. Here, we show that ACTIN7 (ACT7) represents a main actin isoform required for planar polarity of root hair positioning, interacting with the negative modulator ACTIN-INTERACTING PROTEIN1-2 (AIP1-2). ACT7, AIP1-2 and their genetic interaction are required for coordinated planar polarity of ROP downstream of ethylene signalling. Strikingly, AIP1-2 displays hair cell file-enriched expression, restricted by WEREWOLF (WER)-dependent patterning and modified by ethylene and auxin action. Hence, our findings reveal AIP1-2, expressed under control of the WER-dependent patterning machinery and the ethylene signalling pathway, as a modulator of actin-mediated planar polarity.
|
|
| 6. |
- Men, Shuzhen, et al.
(författare)
-
Sterol-dependent endocytosis mediates post-cytokinetic acquisition of PIN2 auxin efflux carrier polarity
- 2008
-
Ingår i: Nature Cell Biology. - : Nature Publishing Group. - 1465-7392 .- 1476-4679. ; 10:2, s. 237-244
-
Tidskriftsartikel (refereegranskat)abstract
- The polarization of yeast and animal cells relies on membrane sterols for polar targeting of proteins to the plasma membrane, their polar endocytic recycling and restricted lateral diffusion1, 2, 3, 4. However, little is known about sterol function in plant-cell polarity5. Directional root growth along the gravity vector requires polar transport of the plant hormone auxin. In Arabidopsis, asymmetric plasma membrane localization of the PIN–FORMED2 (PIN2) auxin transporter directs root gravitropism6, 7, 8, 9, 10. Although the composition of membrane sterols influences gravitropism and localization of two other PIN proteins11, it remains unknown how sterols contribute mechanistically to PIN polarity. Here, we show that correct membrane sterol composition is essential for the acquisition of PIN2 polarity. Polar PIN2 localization is defective in the sterol-biosynthesis mutant cyclopropylsterol isomerase1-1 (cpi1-1) which displays altered sterol composition, PIN2 endocytosis, and root gravitropism. At the end of cytokinesis, PIN2 localizes initially to both newly formed membranes but subsequently disappears from one. By contrast, PIN2 frequently remains at both daughter membranes in endocytosis-defective cpi1-1 cells. Hence, sterol composition affects post-cytokinetic acquisition of PIN2 polarity by endocytosis, suggesting a mechanism for sterol action on establishment of asymmetric protein localization.
|
|
| 7. |
- Nakamura, Moritaka, et al.
(författare)
-
Auxin and ROP GTPase Signaling of Polar Nuclear Migration in Root Epidermal Hair Cells
- 2018
-
Ingår i: Plant Physiology. - : American Society of Plant Biologists. - 0032-0889 .- 1532-2548. ; 176:1, s. 378-391
-
Tidskriftsartikel (refereegranskat)abstract
- Polar nuclear migration is crucial during the development of diverse eukaryotes. In plants, root hair growth requires polar nuclear migration into the outgrowing hair. However, knowledge about the dynamics and the regulatory mechanisms underlying nuclear movements in root epidermal cells remains limited. Here, we show that both auxin and Rho-of-Plant (ROP) signaling modulate polar nuclear position at the inner epidermal plasma membrane domain oriented to the cortical cells during cell elongation as well as subsequent polar nuclear movement to the outer domain into the emerging hair bulge in Arabidopsis (Arabidopsis thaliana). Auxin signaling via the nuclear AUXIN RESPONSE FACTOR7 (ARF7)/ARF19 and INDOLE ACETIC ACID7 pathway ensures correct nuclear placement toward the inner membrane domain. Moreover, precise inner nuclear placement relies on SPIKE1 Rho-GEF, SUPERCENTIPEDE1 Rho-GDI, and ACTIN7 (ACT7) function and to a lesser extent on VTI11 vacuolar SNARE activity. Strikingly, the directionality and/or velocity of outer polar nuclear migration into the hair outgrowth along actin strands also are ACT7 dependent, auxin sensitive, and regulated by ROP signaling. Thus, our findings provide a founding framework revealing auxin and ROP signaling of inner polar nuclear position with some contribution by vacuolar morphology and of actin-dependent outer polar nuclear migration in root epidermal hair cells.
|
|
| 8. |
- Pietra, Stefano, 1980-, et al.
(författare)
-
Arabidopsis SABRE and CLASP interact to stabilize cell division plane orientation and planar polarity
- 2013
-
Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 4, s. 2779-
-
Tidskriftsartikel (refereegranskat)abstract
- The orientation of cell division and the coordination of cell polarity within the plane of the tissue layer (planar polarity) contribute to shape diverse multicellular organisms. The root of Arabidopsis thaliana displays regularly oriented cell divisions, cell elongation and planar polarity providing a plant model system to study these processes. Here we report that the SABRE protein, which shares similarity with proteins of unknown function throughout eukaryotes, has important roles in orienting cell division and planar polarity. SABRE localizes at the plasma membrane, endomembranes, mitotic spindle and cell plate. SABRE stabilizes the orientation of CLASP-labelled preprophase band microtubules predicting the cell division plane, and of cortical microtubules driving cell elongation. During planar polarity establishment, sabre is epistatic to clasp at directing polar membrane domains of Rho-of-plant GTPases. Our findings mechanistically link SABRE to CLASP-dependent microtubule organization, shedding new light on the function of SABRE-related proteins in eukaryotes.
|
|
| 9. |
- Sairanen, Ilkka, et al.
(författare)
-
Soluble Carbohydrates Regulate Auxin Biosynthesis via PIF Proteins in Arabidopsis
- 2012
-
Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 24:12, s. 4907-4916
-
Tidskriftsartikel (refereegranskat)abstract
- Plants are necessarily highly competitive and have finely tuned mechanisms to adjust growth and development in accordance with opportunities and limitations in their environment. Sugars from photosynthesis form an integral part of this growth control process, acting as both an energy source and as signaling molecules in areas targeted for growth. The plant hormone auxin similarly functions as a signaling molecule and a driver of growth and developmental processes. Here, we show that not only do the two act in concert but that auxin metabolism is itself regulated by the availability of free sugars. The regulation of the biosynthesis and degradation of the main auxin, indole-3-acetic acid (IAA), by sugars requires changes in the expression of multiple genes and metabolites linked to several IAA biosynthetic pathways. The induction also involves members of the recently described central regulator PHYTOCHROME-INTERACTING FACTOR transcription factor family. Linking these three known regulators of growth provides a model for the dynamic coordination of responses to a changing environment.
|
|
