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The Molecular Basis of Female Gametophyte Development and Function

English title The Molecular Basis of Female Gametophyte Development and Function
Applicant Grossniklaus Ueli
Number 179553
Funding scheme Project funding (Div. I-III)
Research institution Institut für Pflanzen- und Mikrobiologie Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Embryology, Developmental Biology
Start/End 01.05.2018 - 30.06.2022
Approved amount 1'224'000.00
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All Disciplines (4)

Discipline
Embryology, Developmental Biology
Genetics
Cellular Biology, Cytology
Molecular Biology

Keywords (11)

Arabidopsis; epigenetics; signal transduction; cell specification; chromatin structure; Marchantia; fertilization; cell communication; gametophyte; maternal effects; genomic imprinting

Lay Summary (German)

Lead
The Molecular Basis of Female Gametophyte Development and Function
Lay summary

Die Bildung von Gameten und die maternale Kontrolle der Embryogenese sind fundamentale Prozesse, die in verschiedenen Organismen studiert wurden und allgemein gültige Prinzipien der Entwicklungsbiologie ans Licht brachten. Die Aufklärung der molekularen Mechanismen, welche in Tieren der Etablierung und Interpretation von Positionsinformation oder der Zell-Zell-Kommunikation zugrunde liegen, ist nicht nur von wissenschaftlichem Interesse, sondern haben auch grosse Bedeutung für die Medizin. Im Gegensatz dazu sind diese Schlüsselprozesse in Pflanzen nach wie vor schlecht verstanden und bilden den Fokus dieses Projekts. In Pflanzen entstehen die Gameten nicht direkt nach der Reifeteilung, sondern werden von multizellulären Gametophyten gebildet. Der weibliche Gametophyt besteht in den meisten Arten aus sieben Zellen, die zu vier verschiedenen Zelltypen differenzieren. Dank seiner einfachen und polaren Struktur stellt der weibliche Gametophyt ein ideales Modellsystem dar, um Positionsinformation und Zell-Zell-Kommunikation während der Entwicklung zu studieren. Die Blütenpflanze Arabidopsis thaliana und das Lebermoos Marchantia polymorpha werden als Modelle verwendet, um Schlüsselereignisse in der sexuellen Fortpflanzung zu untersuchen. Dazu gehören die Zell-Spezifikation, mit besonderem Augenmerk auf Transkriptionsfaktoren, welche die Eizelle spezifizieren, sowie die Kommunikation während der Befruchtung, wobei genetische Ansätze benutzt werden, um neue Komponenten eines evolutionär konservierten Signaltransduktionswegs zu identifizieren. Des Weiteren wird die epigenetische Kontrolle der Samenentwicklung erforscht, zum Beispiel um die molekularen Mechanismen der genetischen Prägung, die bisher nur in Säugetieren und Blütenpflanzen beschrieben wurde, besser zu verstehen.

Direct link to Lay Summary Last update: 24.05.2018

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
160336 The Genetic and Molecular Basis of Gametogenesis and Maternal Effects in Arabidopsis 01.05.2015 Project funding (Div. I-III)
204528 Investigating Key Characters for the Domestication of Marama Bean 01.05.2022 Project funding (Div. I-III)

Abstract

In animals, gametogenesis and the maternal control of embryogenesis have been studied extensively at the genetic, cellular, and molecular level. These studies have provided fundamental insights into the mechanisms involved in the establishment and interpretation of positional information, cell communication, and signaling pathways. Many of the genes identified in model organisms were later found to play a crucial role in human disease, and have become prime targets for drug development. Despite much progress over the last years, our knowledge about the molecular mechanisms underlying gametogenesis and seed formation in plants is still very limited. Plant gametes differentiate from the multicellular, haploid gametophytes that are formed from spores through mitotic divisions. The fusion of two pairs of gametes at double fertilization initiates the formation of seeds, which contain the developing embryos. The simple and highly polar female gametophyte, which consists of only seven cells belonging to four cell types, represents an ideal system to study the role of positional information and signaling during development. Using the flowering plant Arabidopsis thaliana and the liverwort Marchantia polymorpha as model systems, this proposal aims to investigate the molecular basis of key events in sexual reproduction, namely cell specification, fertilization, and the epigenetic control of seed development. Our specific aims, which are largely independent of each other, are to:(1) determine the regulatory network controlled by the RKD2 transcription factor specifying egg cell identity in Arabidopsis (2) identify novel components of the plant specific FERONIA signal transduction pathway by forward genetic approaches in the genetically streamlined liverwort Marchantia (3) investigate the evolutionary conservation of the FERONIA pathway in land plants using reverse genetic approaches and CRISPR/Cas9 (4) dissect the role of higher order chromatin organization in regulating the imprinted MEDEA locus(5) unravel the molecular function of the Polycomb group protein MEDEA in the Arabidopsis female gametophyte and young seedTo achieve these aims, we will use a combination of genetic, cell biological, biochemical, and molecular approaches. Many of the methods to be used rely on standard genetic and molecular biology protocols, but others require adaptations and optimizations for the study of the elusive and inaccessible female gametophyte. In addition, we will adapt and establish novel experimental approaches for use in our system, such as (i) novel methods to investigate transcription factor binding sites in specific cell types, (ii) computational network analyses to identify regulatory hubs, (iii) novel sequencing-based techniques to identify causal lesions in Marchantia, (iv) DARPin-based approaches to investigate Polycomb complexes in vivo, and (v) dCas9-based methods to study higher order chromatin organization at specific loci. The experiments described in this proposal will shed light onto fundamental aspects of plant development, such as cell specification, cell-cell communication, and epigenetic gene regulation during development. With nearly 80% of the world’s caloric intake coming directly from the products of plant reproduction (cereals, pulses, fruits, nuts), a better understanding of the underlying mechanisms is highly relevant for future applications. But the results of this project will transcend plant biology and yield novel insights into how developmental mechanisms shape multicellular organisms in general. For example, plant researchers have studied epigenetic phenomena for decades and contributed much to our understanding of the underlying molecular mechanisms, which were then found to also play an important role in the development of human cancer and disease.
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