scholarly journals Independent evolution of lateral inhibition mechanisms in different lineages of land plants: MpFEW RHIZOIDS1 miRNA-mediated lateral inhibition controls rhizoid cell patterning in Marchantia polymorpha

2019 ◽  
Author(s):  
Anna Thamm ◽  
Timothy E Saunders ◽  
Liam Dolan
Keyword(s):  
Lateral Inhibition ◽  
Land Plant ◽  
Land Plants ◽  
Marchantia Polymorpha ◽  
Bhlh Transcription Factor ◽  
Two Dimensional ◽  
Loss Of Function ◽  
Wild Type ◽  
Helix Loop Helix ◽  
Differentiated Cells

ABSTRACTLateral inhibition patterns differentiated cells during development in bacteria, metazoans and land plants. Tip-growing rhizoid cells develop among flat epidermal cells in the epidermis of the early diverging land plant Marchantia polymorpha. We show that the majority of rhizoid cells develop individually but some develop in linear, one-dimensional clusters of between two and seven rhizoid cells in wild type plants. The distribution of rhizoid cells can be accounted for within a simple model of lateral inhibition. The model also predicted that, in the absence of lateral inhibition, rhizoid cell clusters would be two-dimensional with larger clusters than those formed with lateral inhibition. Rhizoid differentiation in Marchantia polymorpha is positively regulated by the ROOT HAIR DEFECTIVE SIX-LIKE1 (MpRSL1) basic Helix Loop Helix (bHLH) transcription factor which is directly repressed by the FEW RHIZOIDS1 (MpFRH1) miRNA. To test if MpFRH1 miRNA acts during lateral inhibition we generated loss-of-function mutants that did not produce the MpFRH1 miRNA. Two-dimensional clusters of rhizoids develop in Mpfrh1loss-of-function (lof) mutants as predicted by the model for plants that lack lateral inhibition. Furthermore, clusters of up to nine rhizoid cells developed in the Mpfrh1lof mutants compared to a maximum number of seven observed in wild type. The higher steady state levels of MpRSL1 mRNA in Mpfrh1lof mutants indicate that MpFRH1-mediated lateral inhibition involves the repression of MpRSL1 activity. Together the modelling and genetic data indicate that the pattern of cell differentiation in the M. polymorpha epidermis is consistent with a lateral inhibition process in which MpFRH1 miRNA represses MpRSL1. This discovery suggests that novel mechanisms of lateral inhibition may operate in different lineages of land plants, unlike metazoans where the conserved Delta-Notch signaling system controls lateral inhibition in diverse metazoan lineages.

scholarly journals Neofunctionalisation of basic helix loop helix proteins occurred when plants colonised the land

2019 ◽  
Author(s):  
Clémence Bonnot ◽  
Alexander J. Hetherington ◽  
Clément Champion ◽  
Holger Breuninger ◽  
Steven Kelly ◽  
...  
Keyword(s):  
Single Cells ◽  
Root Hairs ◽  
Land Plant ◽  
Land Plants ◽  
Marchantia Polymorpha ◽  
Last Common Ancestor ◽  
Single Class ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Class Viii

ABSTRACTROOT HAIR DEFECTIVE SIX-LIKE (RSL) genes control the development of structures – rhizoids, root hairs, gemmae, mucilage papillae – that develop from single cells at the surface of diverse groups of land plants. RSL proteins constitute a subclass (VIIIc) of the basic helix loop helix (bHLH) class VIII transcription factor family. We set out to determine if the function of RSL genes in the control of cell differentiation in land plants was inherited from streptophyte algal ancestor. The Charophyceae are a monophyletic class of streptophyte algae with tissue-like structures and rhizoids. We identified the single class VIII bHLH gene from the charophyceaen alga Chara braunii (CbbHLHVIII). Phylogenetic analysis suggests that this protein is sister to the RSL (bHLH subclass VIIIc) proteins and together they constitute a monophyletic group. Expression of CbbHLHVIII does not compensate for loss of the RSL function in either Marchantia polymorpha or Arabidopsis thaliana. Furthermore, CbbHLHVIII is expressed at sites of morphogenesis in C. braunii – the apices, nodes and gametangia – but not in rhizoids. This indicates that C. braunii class VIII protein is functionally different from land plant RSL proteins; they control rhizoid development in land plants but not in the charophycean algae. These data are consistent with the hypothesis that RSL proteins and their function in the differentiation of cells at the plant surface evolved in the lineage leading to land plants after the divergence of the land plants and C. braunii from their last common ancestor. This may have occurred by neofunctionalisation at or before the colonisation of the land by streptophytes.

scholarly journals Negative regulation of conserved RSL class I bHLH transcription factors evolved independently among land plants

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Suvi Honkanen ◽  
Anna Thamm ◽  
Mario A Arteaga-Vazquez ◽  
Liam Dolan
Keyword(s):  
Transcription Factors ◽  
Root Hairs ◽  
Land Plant ◽  
Feedback Mechanism ◽  
Plant Evolution ◽  
Land Plants ◽  
Class I ◽  
Marchantia Polymorpha ◽  
Helix Loop Helix ◽  
Bhlh Transcription Factors

Basic helix-loop-helix transcription factors encoded by RSL class I genes control a gene regulatory network that positively regulates the development of filamentous rooting cells – root hairs and rhizoids – in land plants. The GLABRA2 transcription factor negatively regulates these genes in the angiosperm Arabidopsis thaliana. To find negative regulators of RSL class I genes in early diverging land plants we conducted a mutant screen in the liverwort Marchantia polymorpha. This identified FEW RHIZOIDS1 (MpFRH1) microRNA (miRNA) that negatively regulates the RSL class I gene MpRSL1. The miRNA and its mRNA target constitute a feedback mechanism that controls epidermal cell differentiation. MpFRH1 miRNA target sites are conserved among liverwort RSL class I mRNAs but are not present in RSL class I mRNAs of other land plants. These findings indicate that while RSL class I genes are ancient and conserved, independent negative regulatory mechanisms evolved in different lineages during land plant evolution.

scholarly journals Deep evolutionary origin of gamete-directed zygote activation by KNOX/BELL transcription factors in green plants

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Tetsuya Hisanaga ◽  
Shota Fujimoto ◽  
Yihui Cui ◽  
Katsutoshi Sato ◽  
Ryosuke Sano ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Transcription Factors ◽  
Chlamydomonas Reinhardtii ◽  
Plant Species ◽  
Land Plant ◽  
Land Plants ◽  
Marchantia Polymorpha ◽  
Mating Types ◽  
Meristem Maintenance

KNOX and BELL transcription factors regulate distinct steps of diploid development in plants. In the green alga Chlamydomonas reinhardtii, KNOX and BELL proteins are inherited by gametes of the opposite mating types and heterodimerize in zygotes to activate diploid development. By contrast, in land plants such as Physcomitrium patens and Arabidopsis thaliana, KNOX and BELL proteins function in meristem maintenance and organogenesis during the later stages of diploid development. However, whether the contrasting functions of KNOX and BELL were acquired independently in algae and land plants is currently unknown. Here, we show that in the basal land plant species Marchantia polymorpha, gamete-expressed KNOX and BELL are required to initiate zygotic development by promoting nuclear fusion in a manner strikingly similar to that in C. reinhardtii. Our results indicate that zygote activation is the ancestral role of KNOX/BELL transcription factors, which shifted toward meristem maintenance as land plants evolved.

Regulation of scute function by extramacrochaete in vitro and in vivo

Development ◽  
1994 ◽  
Vol 120 (12) ◽  
pp. 3595-3603 ◽  
Author(s):  
C.V. Cabrera ◽  
M.C. Alonso ◽  
H. Huikeshoven
Keyword(s):  
Expression Patterns ◽  
Transcription Activation ◽  
Loss Of Function ◽  
Wild Type ◽  
Helix Loop Helix ◽  
In The Wild ◽  
Yeast Assay ◽  
Number Of Cells

The pattern of adult sensilla in Drosophila is established by the dosage-sensitive interaction of two antagonistic groups of genes. Sensilla development is promoted by members of the achaete-scute complex and the daughterless gene whereas it is suppressed by whereas extramacrochaete (emc) and hairy. All these genes encode helix-loop-helix proteins. The products of the achaete-scute complex and daughterless interact to form heterodimers able to activate transcription. In this report, we show that (1) extra-macrochaete forms heterodimers with the achaete, scute, lethal of scute and daughterless products; (2) extramacrochaete inhibits DNA-binding of Achaete, Scute and Lethal of Scute/Daughterless heterodimers and Daughterless homodimers and (3) extramacrochaete inhibits transcription activation by heterodimers in a yeast assay system. In addition, we have studied the expression patterns of scute in wild-type and extramacrochaete mutant imaginal discs. Expression of scute RNA during imaginal development occurs in groups of cells, but high levels of protein accumulate in the nuclei of only a subset of the RNA-expressing cells. The pattern is dynamic and results in a small number of protein-containing cells that correspond to sensillum precursors. extramacrochaete loss-of-function alleles develop extra sensilla and correspondingly display a larger number of cells with scute protein. These cells appear to arise from those that in the wild type already express scute RNA; hence, extramacrochaete is a repressor of scute function whose action may take place post-transcriptionally.

scholarly journals Deep evolutionary origin of gamete-directed zygote activation by KNOX/BELL transcription factors in green plants

2020 ◽  
Author(s):  
Tetsuya Hisanaga ◽  
Shota Fujimoto ◽  
Yihui Cui ◽  
Katsutoshi Sato ◽  
Ryosuke Sano ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Chlamydomonas Reinhardtii ◽  
Plant Species ◽  
Green Alga ◽  
Land Plant ◽  
Land Plants ◽  
Marchantia Polymorpha ◽  
Mating Types ◽  
Meristem Maintenance

AbstractKNOX and BELL transcription factors regulate distinct steps of diploid development in the green lineages. In the green alga Chlamydomonas reinhardtii, KNOX and BELL proteins are inherited by gametes of the opposite mating types, and heterodimerize in zygotes to activate diploid development. By contrast, in land plants such as Physcomitrella and Arabidopsis, KNOX and BELL proteins function in meristem maintenance and organogenesis during the later stages of diploid development. However, whether the contrasting functions of KNOX and BELL were acquired independently in algae and land plants is currently unknown. Here we show that in the basal land plant species Marchantia polymorpha, gamete-expressed KNOX and BELL are required to initiate zygotic development by promoting nuclear fusion in a manner strikingly similar to that of C. reinhardtii. Our results indicate that zygote activation is the ancestral role of KNOX/BELL transcription factors, which shifted toward meristem maintenance as land plants evolved.

NeuroD regulates multiple functions in the developing neural retina in rodent

Development ◽  
1999 ◽  
Vol 126 (1) ◽  
pp. 23-36 ◽  
Author(s):  
E.M. Morrow ◽  
T. Furukawa ◽  
J.E. Lee ◽  
C.L. Cepko
Keyword(s):  
Cell Fate ◽  
Neural Retina ◽  
Bhlh Transcription Factor ◽  
Loss Of Function ◽  
Fourfold Increase ◽  
Helix Loop Helix ◽  
Retinal Explants ◽  
Fate Decision ◽  
And Function

The expression and function of the basic helix-loop-helix (bHLH) transcription factor NeuroD were studied in the developing neural retina in rodent. neuroD was expressed in areas of undetermined retinal cells as well as developing photoreceptors and amacrine interneurons. Expression was maintained in a subset of mature photoreceptors in the adult retina. Using both loss-of-function and gain-of-function approaches, NeuroD was found to play multiple roles in retinal development. (1) NeuroD was found to be a critical regulator of the neuron versus glial cell fate decision. Retinal explants derived from NeuroD-null mice demonstrated a three- to fourfold increase in Muller glia. Forced expression of neuroD in progenitors in rat using retroviruses hastened cell cycle withdrawal and blocked gliogenesis in vivo. (2) NeuroD appeared to regulate interneuron development, favouring amacrine over bipolar differentiation. Forced NeuroD expression resulted in an increase in amacrine interneurons and a decrease in bipolar interneurons. In the complementary experiment, retinae derived from NeuroD-null mice demonstrated a twofold increase in bipolar interneurons and a delay in amacrine differentiation. (3) NeuroD appeared to be essential for the survival of a subset of rod photoreceptors. In conclusion, these results implicate NeuroD in a variety of developmental functions including cell fate determination, differentiation and neuron survival.

scholarly journals Phytophthora palmivora establishes tissue-specific intracellular infection structures in the earliest divergent land plant lineage

2018 ◽  
Vol 115 (16) ◽  
pp. E3846-E3855 ◽  
Author(s):  
Philip Carella ◽  
Anna Gogleva ◽  
Marta Tomaselli ◽  
Carolin Alfs ◽  
Sebastian Schornack
Keyword(s):  
Specific Interaction ◽  
Land Plant ◽  
Land Plants ◽  
Phytophthora Palmivora ◽  
Marchantia Polymorpha ◽  
Broad Host Range ◽  
Tissue Specific ◽  
Plant Trait ◽  
Oomycete Pathogen ◽  
Eukaryotic Microbes

The expansion of plants onto land was a formative event that brought forth profound changes to the earth’s geochemistry and biota. Filamentous eukaryotic microbes developed the ability to colonize plant tissues early during the evolution of land plants, as demonstrated by intimate, symbiosis-like associations in >400 million-year-old fossils. However, the degree to which filamentous microbes establish pathogenic interactions with early divergent land plants is unclear. Here, we demonstrate that the broad host-range oomycete pathogen Phytophthora palmivora colonizes liverworts, the earliest divergent land plant lineage. We show that P. palmivora establishes a complex tissue-specific interaction with Marchantia polymorpha, where it completes a full infection cycle within air chambers of the dorsal photosynthetic layer. Remarkably, P. palmivora invaginates M. polymorpha cells with haustoria-like structures that accumulate host cellular trafficking machinery and the membrane syntaxin MpSYP13B, but not the related MpSYP13A. Our results indicate that the intracellular accommodation of filamentous microbes is an ancient plant trait that is successfully exploited by pathogens like P. palmivora.

scholarly journals Regulation of the Poly(A) Status of Mitochondrial mRNA by Poly(A)-Specific Ribonuclease Is Conserved among Land Plants

2019 ◽  
Vol 61 (3) ◽  
pp. 470-480
Author(s):  
Mai Kanazawa ◽  
Yoko Ikeda ◽  
Ryuichi Nishihama ◽  
Shohei Yamaoka ◽  
Nam-Hee Lee ◽  
...  
Keyword(s):  
Molecular Genetic ◽  
Regulatory System ◽  
Land Plant ◽  
Molecular Genetic Analysis ◽  
Land Plants ◽  
Marchantia Polymorpha ◽  
Mitochondrial Rna ◽  
Cellular Functions ◽  
The Stability

Abstract Regulation of the stability and the quality of mitochondrial RNA is essential for the maintenance of mitochondrial and cellular functions in eukaryotes. We have previously reported that the eukaryotic poly(A)-specific ribonuclease (PARN) and the prokaryotic poly(A) polymerase encoded by AHG2 and AGS1, respectively, coordinately regulate the poly(A) status and the stability of mitochondrial mRNA in Arabidopsis. Mitochondrial function of PARN has not been reported in any other eukaryotes. To know how much this PARN-based mitochondrial mRNA regulation is conserved among plants, we studied the AHG2 and AGS1 counterparts of the liverwort, Marchantia polymorpha, a member of basal land plant lineage. We found that M. polymorpha has one ortholog each for AHG2 and AGS1, named MpAHG2 and MpAGS1, respectively. Their Citrine-fused proteins were detected in mitochondria of the liverwort. Molecular genetic analysis showed that MpAHG2 is essential and functionally interacts with MpAGS1 as observed in Arabidopsis. A recombinant MpAHG2 protein had a deadenylase activity in vitro. Overexpression of MpAGS1 and the reduced expression of MpAHG2 caused an accumulation of polyadenylated Mpcox1 mRNA. Furthermore, MpAHG2 suppressed Arabidopsis ahg2-1 mutant phenotype. These results suggest that the PARN-based mitochondrial mRNA regulatory system is conserved in land plants.

Dominant Alleles of the Basic Helix-Loop-Helix Transcription Factor ATR2 Activate Stress-Responsive Genes in Arabidopsis

Genetics ◽  
2002 ◽  
Vol 161 (3) ◽  
pp. 1235-1246 ◽  
Author(s):  
Gromoslaw A Smolen ◽  
Laura Pawlowski ◽  
Sharon E Wilensky ◽  
Judith Bender
Keyword(s):  
Transcription Factor ◽  
Bhlh Transcription Factor ◽  
Wild Type ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Tryptophan Pathway ◽  
Dark Pigmentation ◽  
Stress Responsive Genes ◽  
Pathway Regulation ◽  
Myb Factor

AbstractMembers of the R/B basic helix-loop-helix (bHLH) family of plant transcription factors are involved in a variety of growth and differentiation processes. We isolated a dominant mutation in an R/B-related bHLH transcription factor in the course of studying Arabidopsis tryptophan pathway regulation. This mutant, atr2D, displayed increased expression of several tryptophan genes as well as a subset of other stress-responsive genes. The atr2D mutation creates an aspartate to asparagine change at a position that is highly conserved in R/B factors. Substitutions of other residues with uncharged side chains at this position also conferred dominant phenotypes. Moreover, overexpression of mutant atr2D, but not wild-type ATR2, conferred pleiotropic effects, including reduced size, dark pigmentation, and sterility. Therefore, atr2D is likely to be an altered-function allele that identifies a key regulatory site in the R/B factor coding sequence. Double-mutant analysis with atr1D, an overexpression allele of the ATR1 Myb factor previously isolated in tryptophan regulation screens, showed that atr2D and atr1D have additive effects on tryptophan regulation and are likely to act through distinct mechanisms to activate tryptophan genes. The dominant atr mutations thus provide tools for altering tryptophan metabolism in plants.

scholarly journals Phytophthora palmivora establishes tissue-specific intracellular infection structures in the earliest divergent land plant lineage

2017 ◽  
Author(s):  
Philip Carella ◽  
Anna Gogleva ◽  
Marta Tomaselli ◽  
Carolin Alfs ◽  
Sebastian Schornack
Keyword(s):  
Specific Interaction ◽  
Land Plant ◽  
Land Plants ◽  
Phytophthora Palmivora ◽  
Marchantia Polymorpha ◽  
Broad Host Range ◽  
Tissue Specific ◽  
Plant Trait ◽  
Oomycete Pathogen ◽  
Eukaryotic Microbes

ABSTRACTThe expansion of plants onto land was a formative event that brought forth profound changes to the Earth’s geochemistry and biota. Filamentous eukaryotic microbes developed the ability to colonize plant tissues early during the evolution of land plants, as demonstrated by intimate symbiosis-like associations in >400 million-year-old fossils. However, the degree to which filamentous microbes establish pathogenic interactions with early divergent land plants is unclear. Here, we demonstrate that the broad host-range oomycete pathogen Phytophthora palmivora colonizes liverworts, the earliest divergent land plant lineage. We show that P. palmivora establishes a complex tissue-specific interaction with Marchantia polymorpha, where it completes a full infection cycle within air chambers of the dorsal photosynthetic layer. Remarkably, P. palmivora invaginates M. polymorpha cells with haustoria-like structures that accumulate host cellular trafficking machinery and the membrane-syntaxin MpSYP13B but not the related MpSYP13A. Our results indicate that the intracellular accommodation of filamentous microbes is an ancient plant trait that is successfully exploited by pathogens like P. palmivora.

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