scholarly journals Control of Leaf Vein Patterning by Regulated Plasmodesma Aperture

2021 ◽  
Author(s):  
Nguyen Manh Linh ◽  
Enrico Scarpella
Keyword(s):  
Plasma Membranes ◽  
Auxin Transport ◽  
Network Formation ◽  
Auxin Signaling ◽  
Animal Cells ◽  
Leaf Vein ◽  
Coordinated Action ◽  
Intercellular Channels ◽  
Vein Patterning ◽  
Multicellular Organisms

To form tissue networks, animal cells migrate and interact through proteins protruding from their plasma membranes. Plant cells can do neither, yet plants form vein networks. How plants do so is unclear, but veins are thought to form by the coordinated action of the polar transport and signal transduction of the plant hormone auxin. However, plants inhibited in both pathways still form veins. Patterning of vascular cells into veins is instead prevented in mutants lacking the function of the GNOM (GN) regulator of auxin transport and signaling, suggesting the existence of at least one more GN-dependent vein-patterning pathway. Here we show that pathway depends on the movement of an auxin signal through plasmodesmata (PDs) intercellular channels. PD permeability is high where veins are forming, lowers between veins and nonvascular tissues, but remains high between vein cells. Impaired ability to regulate PD aperture leads to defects in auxin transport and signaling, ultimately leading to vein patterning defects that are enhanced by inhibition of auxin transport or signaling. GN controls PD aperture regulation, and simultaneous inhibition of auxin signaling, auxin transport, and regulated PD aperture phenocopies null gn mutants. Therefore, veins are patterned by the coordinated action of three GN-dependent pathways: auxin signaling, polar auxin transport, and movement of an auxin signal through PDs. We have identified all the key vein-patterning pathways in plants and an unprecedented mechanism of tissue network formation in multicellular organisms.

Auxin biosynthesis and cellular efflux act together to regulate leaf vein patterning

2020 ◽  
Author(s):  
Irina Kneuper ◽  
William Teale ◽  
Jonathan Edward Dawson ◽  
Ryuji Tsugeki ◽  
Eleni Katifori ◽  
...  
Keyword(s):  
Plant Hormone ◽  
Auxin Transport ◽  
Auxin Biosynthesis ◽  
Mechanical Forces ◽  
Enzyme Expression ◽  
Leaf Vein ◽  
Vein Formation ◽  
Specific Accumulation ◽  
Vein Patterning ◽  
Distal Cell

Abstract Our current understanding of vein development in leaves is based on canalization of the plant hormone auxin into self-reinforcing streams which determine the sites of vascular cell differentiation. By comparison, how auxin biosynthesis affects leaf vein patterning is less well understood. Here, after observing that inhibiting polar auxin transport rescues the sparse leaf vein phenotype in auxin biosynthesis mutants, we propose that the processes of auxin biosynthesis and cellular auxin efflux work in concert during vein development. By using computational modeling, we show that localized auxin maxima are able to interact with mechanical forces generated by the morphological constraints which are imposed during early primordium development. This interaction is able to explain four fundamental characteristics of midvein morphology in a growing leaf: (i) distal cell division; (ii) coordinated cell elongation; (iii) a midvein positioned in the center of the primordium; and (iv) a midvein which is distally branched. Domains of auxin biosynthetic enzyme expression are not positioned by auxin canalization, as they are observed before auxin efflux proteins polarize. This suggests that the site-specific accumulation of auxin, as regulated by the balanced action of cellular auxin efflux and local auxin biosynthesis, is crucial for leaf vein formation.

scholarly journals Polar auxin transport dynamics of primary and secondary vein patterning in dicot leaves

2021 ◽  
Author(s):  
David M Holloway ◽  
Carol L Wenzel
Keyword(s):  
Auxin Transport ◽  
Leaf Growth ◽  
Cellular Level ◽  
Polar Auxin Transport ◽  
Secondary Vein ◽  
Neighbouring Cell ◽  
Transport Dynamics ◽  
Leaf Vein ◽  
Auxin Flux ◽  
Vein Patterning

Abstract The growth regulator auxin plays a central role in the phyllotaxy, shape, and venation patterns of leaves. The auxin spatial localization underlying these phenomena involves polar auxin transport (PAT) at the cellular level, particularly the preferential allocation of PIN efflux proteins to certain areas of the plasma membrane. Two general mechanisms have been studied: an up-the-gradient (UTG) allocation dependent on neighbouring-cell auxin concentrations, and a with-the-flux (WTF) allocation dependent on the flow of auxin across walls. We have developed a combined UTG+WTF model to quantify the observed auxin flows both towards (UTG) and away from (WTF) auxin maxima during primary and secondary vein patterning in leaves. The model simulates intracellular and membrane kinetics and intercellular transport, and is solved for a 2D leaf of several hundred cells. In addition to normal development, modelling of increasing PAT inhibition generates, as observed experimentally: a switch from several distinct vein initiation sites to many less-distinct sites; a delay in vein canalization; inhibited connection of new veins to old; and finally loss of patterning in the margin, loss of vein extension, and confinement of auxin to the margin. The model generates the observed formation of discrete auxin maxima at leaf vein sources and shows the dependence of secondary vein patterning on the efficacy of auxin flux through cells. Simulations of vein patterning and leaf growth further indicate that growth itself may bridge the spatial scale from the cell-cell resolution of the PIN-auxin dynamics to vein patterns on the whole-leaf scale.

scholarly journals Coordination of Tissue Cell Polarity by Auxin Transport and Signaling

2019 ◽  
Author(s):  
Carla Verna ◽  
Sree Janani Ravichandran ◽  
Megan G. Sawchuk ◽  
Nguyen Manh Linh ◽  
Enrico Scarpella
Keyword(s):  
Cell Polarity ◽  
Auxin Transport ◽  
Molecular Genetic Analysis ◽  
Cell Polarization ◽  
Tissue Cell ◽  
Auxin Signaling ◽  
Plant Signaling ◽  
Chemical Induction ◽  
Vein Formation ◽  
Vein Patterning

AbstractCoordination of polarity between cells in tissues is key to multicellular organism development. In animals, coordination of this tissue cell polarity often requires direct cell-cell interactions and cell movements, which are precluded in plants by a wall that separates cells and holds them in place; yet plants coordinate the polarity of hundreds of cells during the formation of the veins in their leaves. Overwhelming experimental evidence suggests that the plant signaling molecule auxin coordinates tissue cell polarity to induce vein formation, but how auxin does so is unclear. The prevailing hypothesis proposes that GNOM, a regulator of vesicle formation during protein trafficking, positions auxin transporters of the PIN-FORMED family to the correct side of the plasma membrane. The resulting cell-to-cell, polar transport of auxin would coordinate tissue cell polarity and would induce vein formation. Here we tested this hypothesis by means of a combination of cellular imaging, molecular genetic analysis, and chemical induction and inhibition. Contrary to predictions of the hypothesis, we find that auxin-induced vein formation occurs in the absence of PIN-FORMED proteins or any known intercellular auxin transporter, that the residual auxin-transport-independent vein-patterning activity relies on auxin signaling, and that a GNOM-dependent signal that coordinates tissue cell polarity to induce vein formation acts upstream of both auxin transport and signaling. Our results reveal synergism between auxin transport and signaling, and their unsuspected control by GNOM, in the coordination of tissue cell polarity during vein patterning, one of the most spectacular and informative expressions of tissue cell polarization in plants.

scholarly journals Coordination of tissue cell polarity by auxin transport and signaling

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Carla Verna ◽  
Sree Janani Ravichandran ◽  
Megan G Sawchuk ◽  
Nguyen Manh Linh ◽  
Enrico Scarpella
Keyword(s):  
Cell Polarity ◽  
Membrane Trafficking ◽  
Auxin Transport ◽  
Cell Polarization ◽  
Tissue Cell ◽  
Auxin Signaling ◽  
Vein Formation ◽  
Dependent Signal ◽  
Vein Patterning ◽  
Auxin Transporter

Plants coordinate the polarity of hundreds of cells during vein formation, but how they do so is unclear. The prevailing hypothesis proposes that GNOM, a regulator of membrane trafficking, positions PIN-FORMED auxin transporters to the correct side of the plasma membrane; the resulting cell-to-cell, polar transport of auxin would coordinate tissue cell polarity and induce vein formation. Contrary to predictions of the hypothesis, we find that vein formation occurs in the absence of PIN-FORMED or any other intercellular auxin-transporter; that the residual auxin-transport-independent vein-patterning activity relies on auxin signaling; and that a GNOM-dependent signal acts upstream of both auxin transport and signaling to coordinate tissue cell polarity and induce vein formation. Our results reveal synergism between auxin transport and signaling, and their unsuspected control by GNOM in the coordination of tissue cell polarity during vein patterning, one of the most informative expressions of tissue cell polarization in plants.

scholarly journals Tissue specific auxin biosynthesis regulates leaf vein patterning

2017 ◽  
Author(s):  
Irina Kneuper ◽  
William Teale ◽  
Jonathan Edward Dawson ◽  
Ryuji Tsugeki ◽  
Klaus Palme ◽  
...  
Keyword(s):  
Auxin Transport ◽  
Spatiotemporal Analysis ◽  
Auxin Biosynthesis ◽  
Cell Stiffness ◽  
List Type ◽  
Tissue Specific ◽  
Leaf Vein ◽  
Vein Formation ◽  
Vein Patterning ◽  
Context Specific

SummaryThe plant hormone auxin (indole-3-acetic acid, IAA) has a profound influence over plant cell growth and differentiation. Current understanding of vein development in leaves is based on the canalization of auxin into self-reinforcing streams which determine the sites of vascular cell differentiation. However, the role of auxin biosynthesis during leaf development in the context of leaf vein patterning has not been much studied so far. Here we characterize the context specific importance of auxin biosynthesis, auxin transport and mechanical regulations in a growing leaf. We show that domains of auxin biosynthesis predict the positioning of vascular cells. In mutants that have reduced capacity in auxin biosynthesis, leaf vein formation is decreased. While exogenous application of auxin does not compensate the loss of vein formation in auxin biosynthesis mutants, inhibition of polar auxin transport does compensate the vein-less phenotype, suggesting that the site-specific accumulation of auxin, which is likely to be mainly caused by the local auxin biosynthesis, is important for leaf vein formation. Our computational model of midvein development brings forth the interplay of cell stiffness and auxin dependent cell division. We propose that local auxin biosynthesis has the integral role in leaf vascular development.HighlightsBuilt spatially and temporally resolved auxin biosynthesis map in growing leaf primordium of Arabidopsis.Expression domains of auxin biosynthetic enzymes within primordia strongly correlated with leaf vein initiation.Results show that domains of auxin biosynthesis within primordia drive leaf vein initiation and patterning.Highlights and eTOC BlurbUsing modelling and a spatiotemporal analysis of auxin biosynthesis and transport, Kneuper et al. show that tissue specific auxin biosynthesis defines places of vein initiation hence underlining the importance of auxin concentration in vein initiation.

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

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.

scholarly journals Maize LAZY1 Mediates Shoot Gravitropism and Inflorescence Development through Regulating Auxin Transport, Auxin Signaling, and Light Response

2013 ◽  
Vol 163 (3) ◽  
pp. 1306-1322 ◽  
Author(s):  
Zhaobin Dong ◽  
Chuan Jiang ◽  
Xiaoyang Chen ◽  
Tao Zhang ◽  
Lian Ding ◽  
...  
Keyword(s):  
Auxin Transport ◽  
Light Response ◽  
Auxin Signaling ◽  
Inflorescence Development ◽  
Shoot Gravitropism

scholarly journals Photoaffinity labelling of a nitrobenzylthioinosine-binding polypeptide from cultured Novikoff hepatoma cells

1986 ◽  
Vol 236 (3) ◽  
pp. 665-670 ◽  
Author(s):  
W P Gati ◽  
J A Belt ◽  
E S Jakobs ◽  
J D Young ◽  
S M Jarvis ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Hepatoma Cells ◽  
Nucleoside Transport ◽  
Facilitated Diffusion ◽  
Animal Cells ◽  
Novikoff Hepatoma

Site-specific binding of nitrobenzylthioinosine (NBMPR) to plasma membranes of some animal cells results in the inhibition of the facilitated diffusion of nucleosides. The present study showed that nucleoside transport in Novikoff UA rat hepatoma cells is insensitive to site-saturating concentrations of NBMPR. Equilibrium binding experiments demonstrated the presence of high-affinity sites for NBMPR in a membrane-enriched fraction from these cells. In the presence of uridine or dipyridamole, specific binding of NBMPR at these sites was inhibited. When Novikoff UA membranes were covalently labelled with [3H]NBMPR by using photoaffinity techniques, specifically bound radioactivity was incorporated exclusively into a polypeptide(s) with an apparent Mr of 72,000-80,000, determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Covalent labelling of this polypeptide was abolished in the presence of excess nitrobenzylthioguanosine (NBTGR) and reduced in the presence of adenosine, uridine or dipyridamole. The apparent Mr of the NBMPR-binding polypeptide in Novikoff UA cells is significantly higher than that reported for corresponding polypeptides in other cell types (Mr 45,000-66,000). When membrane-enriched preparations from S49 mouse lymphoma cells were photolabelled and mixed with labelled NovikoffUA membrane-enriched preparations, gel electrophoresis resolved the NBMPR-binding polypeptides from the two preparations.

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.

scholarly journals CancerGram: An Effective Classifier for Differentiating Anticancer from Antimicrobial Peptides

Pharmaceutics ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1045
Author(s):  
Michał Burdukiewicz ◽  
Katarzyna Sidorczuk ◽  
Dominik Rafacz ◽  
Filip Pietluch ◽  
Mateusz Bąkała ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Cancer Cells ◽  
Plasma Membranes ◽  
Therapeutic Potential ◽  
Kappa Statistic ◽  
R Package ◽  
Bioactive Molecules ◽  
Membrane Composition ◽  
Anticancer Peptides ◽  
Multicellular Organisms

Antimicrobial peptides (AMPs) constitute a diverse group of bioactive molecules that provide multicellular organisms with protection against microorganisms, and microorganisms with weaponry for competition. Some AMPs can target cancer cells; thus, they are called anticancer peptides (ACPs). Due to their small size, positive charge, hydrophobicity and amphipathicity, AMPs and ACPs interact with negatively charged components of biological membranes. AMPs preferentially permeabilize microbial membranes, but ACPs additionally target mitochondrial and plasma membranes of cancer cells. The preference towards mitochondrial membranes is explained by their membrane potential, membrane composition resulting from α-proteobacterial origin and the fact that mitochondrial targeting signals could have evolved from AMPs. Taking into account the therapeutic potential of ACPs and millions of deaths due to cancer annually, it is of vital importance to find new cationic peptides that selectively destroy cancer cells. Therefore, to reduce the costs of experimental research, we have created a robust computational tool, CancerGram, that uses n-grams and random forests for predicting ACPs. Compared to other ACP classifiers, CancerGram is the first three-class model that effectively classifies peptides into: ACPs, AMPs and non-ACPs/non-AMPs, with AU1U amounting to 0.89 and a Kappa statistic of 0.65. CancerGram is available as a web server and R package on GitHub.

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