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A Schnittger

Publications and source records attributed to A Schnittger.

12 recordsLinked to original sources
PubMed2002

TRIPTYCHON and CAPRICE mediate lateral inhibition during trichome and root hair patterning in Arabidopsis.

Trichome patterning in Arabidopsis is a model for the generation of a spacing pattern from initially equivalent cells. We show that the TRIPTYCHON gene that functions in lateral inhibition encodes a single-repeat MYB-related transcription factor that lacks a recognizable activation domain. It has high sequence similarity to the root hair patterning gene CAPRICE. Both genes are expressed in trichomes and act together during lateral inhibition. We further show that TRIPTYCHON and CAPRICE act redundantly in the position-dependent cell fate determination in the root epidermis. Thus, the same lateral inhibition mechanism seems to be involved in both de novo patterning and position-dependent cell determination. We propose a model explaining trichome and root hair patterning by a common mechanism.

Arabidopsis↗
PubMed2002

Trichome morphogenesis: a cell-cycle perspective.

Arabidopsis leaf hairs (trichomes) are polyploid epidermal cells with a predictable branching pattern. More than 15 genes have been identified that are involved in the regulation of branching. The cloning of the ZWICHEL, ANGUSTIFOLIA and STICHEL genes points to two mechanistic aspects of branch formation: (i) a role of the microtubule cytoskeleton; and (ii) a link to the regulation of cell divisions. The latter aspect is supported by the recent identification of an Arabidopsis mutant with multicellular trichomes, the siamese mutant, suggesting that Arabidopsis trichomes are evolutionarily derived from multicellular forms. We speculate that the spatial information for branch formation is derived from mechanisms employed in cell divisions.

Arabidopsis↗
PubMed2001

Ectopic expression of the Arabidopsis AtMYB23 gene induces differentiation of trichome cells.

The control of epidermal cell fate is a complex molecular process and requires the regulatory activity of different transcription factors. Here, we describe the isolation of a member of the Arabidopsis MYB transcription factor family, AtMYB23, that is involved in trichome development. Expression of the AtMYB23 gene under the control of the viral CaMV 35S promoter causes the development of ectopic trichomes. The formation of ectopic trichomes depends on TRANSPARENT TESTA GLABRA1 but not on GLABRA1. The absence of the negative regulator TRIPTYCHON leads to branching of the ectopic trichomes on cotyledons and the formation of ectopic trichomes in the leaf subepidermal cell layer. The CaMV 35S promoter-controlled expression of AtMYB23 can partially rescue the glabra1 mutant phenotype. Together, the presented data indicate that the AtMYB23 gene has partially overlapping functions with GLABRA1 in controlling the initiation of trichome development.

Arabidopsis↗
PubMed1999

Pattern formation and cell differentiation: trichomes in Arabidopsis as a genetic model system.

Arabidopsis trichomes are single-celled hairs that originate from epidermal cells and are distributed regularly on most aerial body parts. During the last decade, trichome formation in Arabidopsis has been established as a genetic and molecular model system to study various general developmental and cellular mechanisms. This review summarizes progress in the investigation of several aspects of trichome development: the spatial regulation of cell fate determination, the regulation of cell differentiation in response to exogenous signals and plant hormones, and the regulation of endoreplication, cell growth, and cell morphogenesis.

Arabidopsis↗
PubMed1999

Plant cells - young at heart?

Dolly has become a synonym for one of the greatest breakthroughs in animal reproductive biology: the regeneration of a whole mammal from a somatic cell nucleus. The equivalent experiments in plants - the regeneration of whole plants from single differentiated cells - are comparatively easy. Does this apparent difference in the developmental potential of animal and plant somatic cells reflect mechanistic differences in the regulation and maintenance of their respective cell differentiation?

Cell Differentiation↗
PubMed1999

Isolation of ethyl methanesulfonate-induced gametophytic mutants in Arabidopsis thaliana by a segregation distortion assay using the multimarker chromosome 1.

The life cycle of plants comprises two alternating generations, the diploid sporophyte (spore-bearing plant) and the haploid gametophyte (gamete-bearing plant). In contrast to animals, the postmeiotic cells give rise to haploid organisms whose function is to produce the gametes and to mediate fertilization. Analysis of gametophyte development and function has been hampered by the difficulty of identifying haplo-phase-specific mutants in conventional mutagenesis screens. Here we use a genetic strategy that is based on segregation distortion of nearby visible markers to screen for EMS-induced gametophytic mutants in Arabidopsis thaliana. Using the multiple marker chromosome mm1 we have isolated seven lines that displayed an altered segregation of markers. Reciprocal backcrosses of these lines showed a marked reduction of the transmission of the male and/or female gametes. Phenotypic analysis revealed that different aspects of either gametophytic development or function were affected. Three male gametophytic lines showed specific arrests during pollen development. One male gametophytic line was specifically defective in pollen tube elongation. Three gametophytic lines showed variable defects in both male and female gametophytic development.

Arabidopsis↗
PubMed1999

Generation of a spacing pattern: the role of triptychon in trichome patterning in Arabidopsis.

Trichomes in Arabidopsis are single-celled hairs that exhibit a regular spacing pattern. Here, the role of TRIPTYCHON (TRY) in the generation of this spacing pattern is studied. By using genetic mosaics, we demonstrate that the formation of trichome clusters in try mutants is not correlated with cell lineage, indicating that TRY is required to single out trichome cells in a process involving cellular interactions. The genetic interactions of TRY, GLABRA1 (GL1), and TRANSPARENT TESTA GLABRA (T TG) in trichome patterning are assessed by determining the cluster frequency in various genetic combinations. It is shown that TRY acts as a negative regulator of GL1- and TTG-dependent pathways. Furthermore, it is demonstrated that trichome initiation in ttg-1, a strong ttg allele, is rescued almost to wild-type levels in a try background in which GL1 is expressed under the control of the cauliflower mosaic virus 35S promoter, indicating that T TG acts upstream of GL1 and TRY. These findings are incorporated into a model to explain the generation of a trichome spacing pattern from a homogeneous population of epidermal cells.

Arabidopsis↗
PubMed1998

Spatial regulation of trichome formation in Arabidopsis thaliana.

Trichomes in Arabidopsis are single-celled hairs that develop from epidermal cells regularly distributed on leaves, sepals and stems. Trichome formation in Arabidopsis is emerging as a genetic and molecular model system for the analysis of the spatial regulation of cell type specification in plants. In this review we focus on two aspects of trichome initiation: the regulation of organ and tissue layer specificity and the establishment of an epidermal spacing pattern.

Arabidopsis↗
PubMed1998

Tissue layer and organ specificity of trichome formation are regulated by GLABRA1 and TRIPTYCHON in Arabidopsis.

In animal development, cellular diversity is generated within tissues which in turn are derived from germ layers. Similar to the germ layers in animals, plants establish three distinct tissue layers early in development which each give rise to a distinct set of cell types. To investigate the role of tissue-layer-specific cues in generating plant cellular diversity we studied the spatial regulation of an epidermal cell type, trichomes (hairs), by the two genes, GLABRA1 (GL1) and TRIPTYCHON (TRY). Ubiquitous expression of the positive regulator GL1 in the absence of the negative regulator TRY leads to ectopic trichome formation not only on additional organs but also in subepidermal tissue layers. Trichomes in inner tissue layers can differentiate the same morphology and show a spacing pattern comparable to trichomes in the epidermis. This clearly shows that cell type specification takes place downstream of tissue-specific cues. We propose a model of how the tissue and organ specificity of trichome induction is regulated in normal development.

Arabidopsis↗
PubMed1996

Epidermal fate map of the Arabidopsis shoot meristem.

The shoot meristem generates all of the aerial structures of an adult plant. It is organized in three layers which produce the epidermis (L1 layer) and the subepidermal layers (L2 and L3). The origin of adult structures has previously been fate mapped to the primary meristem for L2 and L3 tissues. In this work we constructed a fate map of L1 cells in the embryonic shoot meristem. Using the trichome mutation stichel as an epidermal marker, we analyzed 153 plants that included 178 sectors. Sectors on early leaves were found to be smaller and occurred more frequently than those on late leaves. Sectors on late leaves also appeared often to affect more than one leaf. In general, the width and extent of sectors were found to be variable rather than cell lineage-restricted. Our analysis allowed us to assign the most likely fates of L1 precursor cells within the embryonic shoot meristem. The results suggest that the meristem integrates growth dynamics and patterning of all three tissues. In contrast to this coordinated growth behavior of meristematic cells, we found a difference in the lineage restrictions between the L1 and the L2 for the formation of axillary buds.

Arabidopsis↗