The role of auxin signaling in early embryo pattern formation

2015 ◽  
Vol 28 ◽  
pp. 99-105 ◽  
Author(s):  
Margot E Smit ◽  
Dolf Weijers
Keyword(s):  
Pattern Formation ◽  
Early Embryo ◽  
Auxin Signaling

Apical-basal pattern formation in the Arabidopsis embryo: studies on the role of the gnom gene

Development ◽  
1993 ◽  
Vol 117 (1) ◽  
pp. 149-162 ◽  
Author(s):  
U. Mayer ◽  
G. Buttner ◽  
G. Jurgens
Keyword(s):  
Pattern Formation ◽  
Root Formation ◽  
Asymmetric Cell Division ◽  
Early Embryo ◽  
The Body ◽  
Wild Type ◽  
Early Effect ◽  
Normal Number ◽  
Mutant Seedling

gnom is one of several genes that make substantial contributions to pattern formation along the apical-basal axis of polarity in the Arabidopsis embryo as indicated by the mutant seedling phenotype. The apical and basal end regions of the body pattern, which include the meristems of the shoot and the root, fail to form, and a minority of mutant embryos lack morphological features of apical-basal polarity. We have investigated the developmental basis of the gnom mutant phenotype, taking advantage of a large number of EMS-induced mutant alleles. The seedling phenotype has been traced back to the early embryo in which the asymmetric division of the zygote is altered, now producing two nearly equal-sized cells. The apical daughter cell then undergoes abnormal divisions, resulting in an octant embryo with about twice the normal number of cells while the uppermost derivative of the basal cell fails to become the hypophysis, which normally contributes to root development. Consistent with this early effect, gnom appears to be epistatic to monopteros in doubly mutant embryos, suggesting that, without prior gnom activity, the monopteros gene cannot promote root and hypocotyl development. On the other hand, when root formation was induced in bisected seedlings, wild-type responded whereas gnom mutants failed to produce a root but formed callus instead. These results suggest that gnom activity promotes asymmetric cell division which we believe is necessary both for apical-basal pattern formation in the early embryo and for root formation in tissue culture.

Role of Nuclei in Liesegang Pattern Formation: Insights from Experiment and Reaction-Diffusion Simulation

2018 ◽  
Vol 122 (6) ◽  
pp. 3669-3676 ◽  
Author(s):  
Masaki Itatani ◽  
Qing Fang ◽  
Kei Unoura ◽  
Hideki Nabika
Keyword(s):  
Pattern Formation ◽  
Reaction Diffusion ◽  
Diffusion Simulation

Citral, an inhibitor of retinoic acid synthesis, modifies pattern formation during limb regeneration in the axolotl Ambystoma mexicanum

1999 ◽  
Vol 77 (11) ◽  
pp. 1835-1837 ◽  
Author(s):  
Steven R Scadding
Keyword(s):  
Retinoic Acid ◽  
Pattern Formation ◽  
Limb Regeneration ◽  
Acid Synthesis ◽  
Ambystoma Mexicanum

While the effects of exogenous retinoids on amphibian limb regeneration have been studied extensively, the role of endogenous retinoids is not clear. Hence, I wished to investigate the role of endogenous retinoic acid during axolotl limb regeneration. Citral is a known inhibitor of retinoic acid synthesis. Thus, I treated regenerating limbs of the larval axolotl Ambystoma mexicanum with citral. The result of this inhibition of retinoic acid synthesis was that limb regeneration became extremely irregular and hypomorphic, with serious pattern defects, or was inhibited altogether. I conclude that endogenous retinoic acid plays an important role in pattern formation during limb regeneration.

‘Generic’ physical mechanisms of morphogenesis and pattern formation

Development ◽  
1990 ◽  
Vol 110 (1) ◽  
pp. 1-18 ◽  
Author(s):  
S.A. Newman ◽  
W.D. Comper
Keyword(s):  
Pattern Formation ◽  
Reaction Diffusion ◽  
Physical Mechanisms ◽  
Extracellular Matrix Components ◽  
Genetic Mechanisms ◽  
Chemical Waves ◽  
Phylogenetic Lineages ◽  
Living Tissues ◽  
Highly Evolved

The role of ‘generic’ physical mechanisms in morphogenesis and pattern formation of tissues is considered. Generic mechanisms are defined as those physical processes that are broadly applicable to living and non-living systems, such as adhesion, surface tension and gravitational effects, viscosity, phase separation, convection and reaction-diffusion coupling. They are contrasted with ‘genetic’ mechanisms, a term reserved for highly evolved, machine-like, biomolecular processes. Generic mechanisms acting upon living tissues are capable of giving rise to morphogenetic rearrangements of cytoplasmic, tissue and extracellular matrix components, sometimes leading to ‘microfingers’, and to chemical waves or stripes. We suggest that many morphogenetic and patterning effects are the inevitable outcome of recognized physical properties of tissues, and that generic physical mechanisms that act on these properties are complementary to, and interdependent with genetic mechanisms. We also suggest that major morphological reorganizations in phylogenetic lineages may arise by the action of generic physical mechanisms on developing embryos. Subsequent evolution of genetic mechanisms could stabilize and refine developmental outcomes originally guided by generic effects.

Genetic analysis of pattern formation in the Arabidopsis embryo

Development ◽  
1991 ◽  
Vol 113 (Supplement_1) ◽  
pp. 27-38 ◽  
Author(s):  
Gerd Jürgens ◽  
Ulrike Mayer ◽  
Torres Ruiz Ramon A. ◽  
Thomas Berleth ◽  
Simon Miséra
Keyword(s):  
Pattern Formation ◽  
Large Scale ◽  
Early Embryo ◽  
Flowering Plant ◽  
Abnormal Development ◽  
Mutant Seedling ◽  
Basic Body ◽  
Plant Embryo ◽  
Embryonic Pattern Formation ◽  
Plant Arabidopsis Thaliana

Virtually nothing is known about the mechanisms that generate the basic body pattern in plant embryogenesis. As a first step towards the analysis of pattern formation, we have isolated and begun to characterise putative pattern mutants in the flowering plant, Arabidopsis thaliana. A large-scale screen for morphologically abnormal seedling mutants yielded about 250 lines for further study, and genetic evidence suggests saturation of the genome for this kind of mutation. The phenotypes of putative pattern mutants fall into distinct categories, classes and groups, which may reflect specific aspects of embryonic pattern formation. Mutant seedling phenotypes result from abnormal development in the early embryo. The implications of our findings are discussed with regard to the prospects for a mechanistic understanding of pattern formation in the plant embryo.

Reorganization of membrane contacts prior to apoptosis in the Drosophila retina: the role of the IrreC-rst protein

Development ◽  
1996 ◽  
Vol 122 (6) ◽  
pp. 1931-1940 ◽  
Author(s):  
C. Reiter ◽  
T. Schimansky ◽  
Z. Nie ◽  
K.F. Fischbach
Keyword(s):  
Pattern Formation ◽  
Pigment Cells ◽  
Immunoglobulin Superfamily ◽  
Specific Cell ◽  
Axonal Pathfinding ◽  
Single Row ◽  
Cell Contacts ◽  
Regulated Expression ◽  
Membrane Contacts

The final step of pattern formation in the developing retina of Drosophila is the elimination of excess cells between ommatidia and the differentiation of the remaining cells into secondary and tertiary pigment cells. Temporally and spatially highly regulated expression of the irregular chiasmC-roughest protein, an adhesion molecule of the immunoglobulin superfamily known to be involved in axonal pathfinding, is essential for correct sorting of cell-cell contacts in the pupal retina without which the ensuing wave of apoptosis does not occur. Irregular chiasmC-roughest accumulates strongly at the borders between primary pigment and interommatidial cells. Mutant and misexpression analysis show that this accumulation of the irregular chiasmC-roughest protein is necessary for aligning interommatidial cells in a single row. This reorganisation is a prerequisite for the identification of death candidates. Irregular chiasmC-roughest function in retinal development demonstrates the importance of specific cell contacts for assignment of the apoptotic fate.

scholarly journals Genetic analysis of the Arabidopsis TIR1/AFB auxin receptors reveals both overlapping and specialized functions

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Michael J Prigge ◽  
Matthieu Platre ◽  
Nikita Kadakia ◽  
Yi Zhang ◽  
Kathleen Greenham ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Early Embryo ◽  
Wild Type ◽  
The Family ◽  
Dependent Inhibition ◽  
Root Gravitropism ◽  
Specialized Function ◽  
Mutant Lines

The TIR1/AFB auxin co-receptors mediate diverse responses to the plant hormone auxin. The Arabidopsis genome encodes six TIR1/AFB proteins representing three of the four clades that were established prior to angiosperm radiation. To determine the role of these proteins in plant development we performed an extensive genetic analysis involving the generation and characterization of all possible multiply-mutant lines. We find that loss of all six TIR1/AFB proteins results in early embryo defects and eventually seed abortion, and yet a single wild-type allele of TIR1 or AFB2 is sufficient to support growth throughout development. Our analysis reveals extensive functional overlap between even the most distantly related TIR1/AFB genes except for AFB1. Surprisingly, AFB1 has a specialized function in rapid auxin-dependent inhibition of root growth and early phase of root gravitropism. This activity may be related to a difference in subcellular localization compared to the other members of the family.

scholarly journals Rewiring of auxin signaling under persistent shade

2018 ◽  
Vol 115 (21) ◽  
pp. 5612-5617 ◽  
Author(s):  
Ornella Pucciariello ◽  
Martina Legris ◽  
Cecilia Costigliolo Rojas ◽  
María José Iglesias ◽  
Carlos Esteban Hernando ◽  
...  
Keyword(s):  
Physiological Role ◽  
System Level ◽  
Early Event ◽  
Auxin Signaling ◽  
Detailed Knowledge ◽  
Shade Avoidance ◽  
Growth Responses ◽  
Molecular Events ◽  
Elevated Expression

Light cues from neighboring vegetation rapidly initiate plant shade-avoidance responses. Despite our detailed knowledge of the early steps of this response, the molecular events under prolonged shade are largely unclear. Here we show that persistent neighbor cues reinforce growth responses in addition to promoting auxin-responsive gene expression in Arabidopsis and soybean. However, while the elevation of auxin levels is well established as an early event, in Arabidopsis, the response to prolonged shade occurs when auxin levels have declined to the prestimulation values. Remarkably, the sustained low activity of phytochrome B under prolonged shade led to (i) decreased levels of PHYTOCHROME INTERACTING FACTOR 4 (PIF4) in the cotyledons (the organs that supply auxin) along with increased levels in the vascular tissues of the stem, (ii) elevated expression of the PIF4 targets INDOLE-3-ACETIC ACID 19 (IAA19) and IAA29, which in turn reduced the expression of the growth-repressive IAA17 regulator, (iii) reduced abundance of AUXIN RESPONSE FACTOR 6, (iv) reduced expression of MIR393 and increased abundance of its targets, the auxin receptors, and (v) elevated auxin signaling as indicated by molecular markers. Mathematical and genetic analyses support the physiological role of this system-level rearrangement. We propose that prolonged shade rewires the connectivity between light and auxin signaling to sustain shade avoidance without enhanced auxin levels.

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