scholarly journals Ontogenetic Changes in Auxin Biosynthesis and Distribution Determine the Organogenic Activity of the Shoot Apical Meristem in pin1 Mutants

2019 ◽  
Vol 20 (1) ◽  
pp. 180 ◽  
Author(s):  
Alicja Banasiak ◽  
Magdalena Biedroń ◽  
Alicja Dolzblasz ◽  
Mateusz Adam Berezowski
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Auxin Transport ◽  
Vascular System ◽  
Auxin Biosynthesis ◽  
Wild Type ◽  
Ontogenetic Changes ◽  
Auxin Distribution ◽  
Stem Development ◽  
Knockout Mutation

In the shoot apical meristem (SAM) of Arabidopsis, PIN1-dependent polar auxin transport (PAT) regulates two crucial developmental processes: organogenesis and vascular system formation. However, the knockout mutation in the PIN1 gene does not fully inhibit these two processes. Therefore, we investigated a potential source of auxin for organogenesis and vascularization during inflorescence stem development. We analyzed auxin distribution in wild-type (WT) and pin1 mutant plants using a refined protocol of auxin immunolocalization; auxin activity, with the response reporter pDR5:GFP; and expression of auxin biosynthesis genes YUC1 and YUC4. Our results revealed that regardless of the functionality of PIN1-mediated PAT, auxin is present in the SAM and vascular strands. In WT plants, auxin always accumulates in all cells of the SAM, whereas in pin1 mutants, its localization within the SAM changes ontogenetically and is related to changes in the structure of the vascular system, organogenic activity of SAM, and expression levels of YUC1 and YUC4 genes. Our findings indicate that the presence of auxin in the meristem of pin1 mutants is an outcome of at least two PIN1-independent mechanisms: acropetal auxin transport from differentiated tissues with the use of vascular strands and auxin biosynthesis within the SAM.

scholarly journals Toward a 3D model of phyllotaxis based on a biochemically plausible auxin-transport mechanism

2018 ◽  
Author(s):  
Félix P. Hartmann ◽  
Pierre Barbier de Reuille ◽  
Cris Kuhlemeier
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Auxin Transport ◽  
Vascular System ◽  
Three Dimensional ◽  
Integrative Approach ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Leaf Formation ◽  
Cell Layers

AbstractPolar auxin transport lies at the core of many self-organizing phenomena sustaining continuous plant organogenesis. In angiosperms, the shoot apical meristem is a potentially unique system in which the two main modes of auxin-driven patterning— convergence and canalization—co-occur in a coordinated manner and in a fully three-dimensional geometry. In the epidermal layer, convergence points form, from which auxin is canalized towards inner tissue. Each of these two patterning processes has been extensively investigated separately, but the integration of both in the shoot apical meristem remains poorly understood. We present here a first attempt of a three-dimensional model of auxin-driven patterning during phyllotaxis. We base our simulations on a biochemically plausible mechanism of auxin transport proposed by Cieslak et al. (2015) which generates both convergence and canalization patterns. We are able to reproduce most of the dynamics of PIN1 polarization in the meristem, and we explore how the epidermal and inner cell layers act in concert during phyllotaxis. In addition, we discuss the mechanism by which initiating veins connect to the already existing vascular system.Author summaryThe regularity of leaf arrangement around stems has long puzzled scientists. The key role played by the plant hormone auxin is now well established. On the surface of the tissue responsible for leaf formation, auxin accumulates at several points, from which new leaves eventually emerge. Auxin also guides the progression of new veins from the nascent leaves to the vascular system of the plant. Models of auxin transport have been developed to explain either auxin accumulation or auxin-driven venation. We propose the first three-dimensional model embracing both phenomena using a unifying mechanism of auxin transport. This integrative approach allows an assessment of our present knowledge on how auxin contributes to the early development of leaves. Our model reproduces many observations of auxin dynamics. It highlights how the inner and epidermal tissues act together to position new leaves. We also show that an additional, yet unknown, mechanism is required to attract new developing veins towards the main vasculature of the plant.

Characterisation of three shoot apical meristem mutants of Arabidopsis thaliana

Development ◽  
1992 ◽  
Vol 116 (2) ◽  
pp. 397-403 ◽  
Author(s):  
H. M. Ottoline Leyser ◽  
I. J. Furner
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Growth ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Floral Development ◽  
Wild Type ◽  
Recessive Mutations ◽  
Phenotypic Characterisation ◽  
Dicotyledonous Plants ◽  
And Function

The shoot apical meristem of dicotyledonous plants is highly regulated both structurally and functionally, but little is known about the mechanisms involved in this regulation. Here we describe the genetic and phenotypic characterisation of recessive mutations at three loci of Arabidopsis thaliana in which meristem structure and function are disrupted. The loci are Clavata1 (Clv1), Fasciata1 (Fas1) and Fasciata2 (Fas2). Plants mutant at these loci are fasciated having broad, flat stems and disrupted phyllotaxy. In all cases, the fasciations are associated with shoot apical meristem enlargement and altered floral development. While all the mutants share some phenotypic features they can be divided into two classes. The pleiotropic fas1 and fas2 mutants are unable to initiate wild- type organs, show major alterations in meristem structure and have reduced root growth. In contrast, clv1 mutant plants show near wild-type organ phenotypes, more subtle changes in shoot apical meristem structure and wild-type root growth.

scholarly journals Feedback from Lateral Organs Controls Shoot Apical Meristem Growth by Modulating Auxin Transport

2018 ◽  
Vol 44 (2) ◽  
pp. 204-216.e6 ◽  
Author(s):  
Bihai Shi ◽  
Xiaolu Guo ◽  
Ying Wang ◽  
Yuanyuan Xiong ◽  
Jin Wang ◽  
...  
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Auxin Transport ◽  
Lateral Organs

How repeated epiphylly correlates with gene expression of resident knox1 in the leaves of tobacco epiphyllous shoots

2006 ◽  
Vol 1 (2) ◽  
pp. 263-274 ◽  
Author(s):  
Kai Müller ◽  
Jinxing Lin ◽  
Rainer Fischer ◽  
Dirk Prüfer
Keyword(s):  
Gene Expression ◽  
Transgenic Plant ◽  
Shoot Apical Meristem ◽  
Plant Material ◽  
Apical Meristem ◽  
Leaf Primordia ◽  
Wild Type ◽  
Expression Domain ◽  
Enhanced Expression ◽  
Founder Cells

AbstractThe tobacco knox1 genes tokn1 and tokn2 were isolated and their neomorphic capacities were tested while expressed in tobacco and potato. In addition, their neomorphic capacities were compared to barley bkn3 transgenic plant material. While tokn2 and bkn3 induced epiphylly in tobacco and supercompound leaves in potato, tokn1 failed to produce such prominent knox1 specific phenotypes. In wild type tobacco, alleles of the tokn genes were found to be expressed within distinct zones of the shoot apical meristem (SAM), leaving out regions that correlated with leaf founder cells [1]. In contrast, the expression of the tokn genes was detected throughout the meristem and in leaf primordia of epiphyllous shoots that developed in tobacco over-expressing the barley hooded gene bkn3. It was determined that such extended expression domains of resident tobacco knox1 genes were mediated through an enhanced expression domain of bkn3 within the tissue confined to the epiphylls, and this contributed to “repeated epiphylly”, i.e. an iterated development of epiphyllous shoots on leaves of progenitor epiphylls.

scholarly journals Alignment between PIN1 Polarity and Microtubule Orientation in the Shoot Apical Meristem Reveals a Tight Coupling between Morphogenesis and Auxin Transport

PLoS Biology ◽  
2010 ◽  
Vol 8 (10) ◽  
pp. e1000516 ◽  
Author(s):  
Marcus G. Heisler ◽  
Olivier Hamant ◽  
Pawel Krupinski ◽  
Magalie Uyttewaal ◽  
Carolyn Ohno ◽  
...  
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Auxin Transport ◽  
Tight Coupling ◽  
Microtubule Orientation

scholarly journals Vascular structure contributes to shoot sectoriality in Selaginella kraussiana

2016 ◽  
Vol 85 (3) ◽  
Author(s):  
Edyta M. Gola ◽  
Judith A. Jernstedt
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Vascular System ◽  
Shoot Development ◽  
Specific Structure ◽  
Developmental Changes ◽  
Vascular Structure ◽  
Vascular Connections

<em>Selaginella</em> species are characterized by regular anisotomous dichotomous divisions of the shoot apical meristem, giving rise to two new axes (branches) which differ in size. A vital process is the formation of vascular connections, which enables continuous communication and consequent functional and developmental integration of a plant during branching. Here, we present the sequence of developmental changes in the vascular system of <em>Selaginella kraussiana</em> related to dichotomous branching. Stem vasculature in <em>Selaginella kraussiana</em> consists of two meristeles which change in arrangement during shoot development. Using dye tracers, we documented developmental functional isolation of meristeles associated with the specific structure of the stelar system, which results in a spatiotemporal sectoriality of the shoot. We discuss sectoriality in terms of possible significance for shoot development.

The shoot apical meristem and development of vascular architectureThis review is one of a selection of papers published on the Special Theme of Shoot Apical Meristems.

2006 ◽  
Vol 84 (11) ◽  
pp. 1660-1671 ◽  
Author(s):  
Nancy G. Dengler
Keyword(s):  
Arabidopsis Thaliana ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Leucine Zipper ◽  
Vascular Tissue ◽  
Vascular System ◽  
Expression Patterns ◽  
Three Dimensional ◽  
Integrative Model ◽  
Class Iii

The shoot apical meristem (SAM) functions to generate external architecture and internal tissue pattern as well as to maintain a self-perpetuating population of stem-cell-like cells. The internal three-dimensional architecture of the vascular system corresponds closely to the external arrangement of lateral organs, or phyllotaxis. This paper reviews this correspondence for dicotyledonous plants in general and in Arabidopsis thaliana (L.) Heynh., specifically. Analysis is partly based on the expression patterns of the class III homeodomain-leucine zipper transcription factor ARABIDOPSIS THALIANA HOMEOBOX GENE 8 (ATHB8), a marker of the procambial and preprocambial stages of vascular development, and on the anatomical criteria for recognizing vascular tissue pattern. The close correspondence between phyllotaxis and vascular pattern present in mature tissues arises at early stages of development, at least by the first plastochron of leaf primordium outgrowth. Current literature provides an integrative model in which local variation in auxin concentration regulates both primordium formation on the SAM and the first indications of a procambial prepattern in the position of primordium leaf trace as well as in the elaboration of leaf vein pattern. The prospects for extending this model to the development of the complex three-dimensional vascular architecture of the shoot are promising.

scholarly journals The AtCRK5 Protein Kinase Is Required to Maintain the ROS NO Balance Affecting the PIN2-Mediated Root Gravitropic Response in Arabidopsis

2021 ◽  
Vol 22 (11) ◽  
pp. 5979
Author(s):  
Ágnes Cséplő ◽  
Laura Zsigmond ◽  
Norbert Andrási ◽  
Abu Imran Baba ◽  
Nitin M. Labhane ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Auxin Transport ◽  
Root Tip ◽  
Wild Type ◽  
Root Tips ◽  
H2o2 Treatment ◽  
Gravitropic Response ◽  
Auxin Distribution ◽  
Regulatory Loop ◽  
Oxidative Stress Inducer

The Arabidopsis AtCRK5 protein kinase is involved in the establishment of the proper auxin gradient in many developmental processes. Among others, the Atcrk5-1 mutant was reported to exhibit a delayed gravitropic response via compromised PIN2-mediated auxin transport at the root tip. Here, we report that this phenotype correlates with lower superoxide anion (O2•−) and hydrogen peroxide (H2O2) levels but a higher nitric oxide (NO) content in the mutant root tips in comparison to the wild type (AtCol-0). The oxidative stress inducer paraquat (PQ) triggering formation of O2•− (and consequently, H2O2) was able to rescue the gravitropic response of Atcrk5-1 roots. The direct application of H2O2 had the same effect. Under gravistimulation, correct auxin distribution was restored (at least partially) by PQ or H2O2 treatment in the mutant root tips. In agreement, the redistribution of the PIN2 auxin efflux carrier was similar in the gravistimulated PQ-treated mutant and untreated wild type roots. It was also found that PQ-treatment decreased the endogenous NO level at the root tip to normal levels. Furthermore, the mutant phenotype could be reverted by direct manipulation of the endogenous NO level using an NO scavenger (cPTIO). The potential involvement of AtCRK5 protein kinase in the control of auxin-ROS-NO-PIN2-auxin regulatory loop is discussed.

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