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The Role of RGL2 and the Seed Coat in Arabidopsis Seed Dormancy

English title The Role of RGL2 and the Seed Coat in Arabidopsis Seed Dormancy
Applicant Lopez-Molina Luis
Number 132591
Funding scheme Project funding
Research institution Département de Biologie Végétale Faculté des Sciences Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Molecular Biology
Start/End 01.01.2011 - 30.09.2014
Approved amount 433'483.00
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Keywords (12)

Seed dormancy; Seed coat; Arabidopsis; Abscisic acid (ABA); Gibberellic acid (GA); RGL2; DELLA factors; ABI3 ABI5; gibberellins; Abscisic acid; seed germination; ABI5

Lay Summary (English)

Lead
Lay summary
Seeds are of vital importance for life on earth, including that of humans. Indeed, seeds are an essential source of food for animals since plants store in seeds high amounts of nutritive substances (e.g. carbohydrates, oils) to fuel germination. When seeds germinate, they abandon a state highly resistant to heat and drought to develop into a young and fragile young seedling. It is therefore not surprising that seed germination is a tightly controlled process, responding to environmental factors such as water quality (e.g. containing high or low salt) or light quality (e.g. sunlight versus canopy light). Prior to germination, seeds must first lose their dormancy. Indeed, plants generate seeds in a dormant state, i.e. a state where germination will not take place even under favorable germination conditions such as imbibition by water. Dormancy may prevent germination out of season or avoid competition among seeds of the same species by preventing their germination in the same location. The mechanisms preventing the germination of dormant seeds are mostly unknown. A better understanding of seed dormancy is important for agriculture since it prevents precocious germination in the growing plant and thus loss of crop yield.Two key properties characterize dormant seeds: 1) the seed coat is essential to maintain the dormant state since its removal will trigger the growth and greening and the embryo; 2) dormant seeds synthesize high amounts of the phytohormone abscisic acid (ABA) which is essential to block their germination. How the seed coat exerts its inhibitory role and how dormant seeds synthesize ABA is unknown.Our project proposal intends to further explore the role of the seed coat and the molecular genetic mechanisms leading to ABA accumulation. We also wish to investigate whether these two key properties of seeds are related.To address these issues, we have developed a "seed coat bedding" assay that physically separates the seed coat and the embryo while still keeping active the repression of germination by the seed coat. This assay shows that the seed coat is a tissue producing diffusible signals necessary to prevent embryonic growth. Furthermore, the assay allows using seed coats of different genotypic backgrounds to genetically dissect the germination-repressing activities produced by the seed coat. We intend to identify the germination inhibitory compounds released by dormant seed coats and ask whether ABA is one of them. Furthermore, we will address the hypothesis that high ABA production in dormant seeds results from constitutive production of RGL2, a factor previously shown to promote ABA accumulation in non-dormant seeds.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
A seed coat bedding assay to genetically explore in vitro how the endosperm controls seed germination in Arabidopsis thaliana.
Lee Keun Pyo, Lopez-Molina Luis (2013), A seed coat bedding assay to genetically explore in vitro how the endosperm controls seed germination in Arabidopsis thaliana., in Journal of Visualized Experiments (JoVE), 81, 5.
A seed coat bedding assay shows that RGL2-dependent release of abscisic acid by the endosperm controls embryo growth in Arabidopsis dormant seeds.
Lee Keun Pyo, Piskurewicz Urszula, Turecková Veronika, Strnad Miroslav, Lopez-Molina Luis (2012), A seed coat bedding assay shows that RGL2-dependent release of abscisic acid by the endosperm controls embryo growth in Arabidopsis dormant seeds., in Proceedings of the National Academy of Sciences of the United States of America, 107(44), 19108-13.
Control of seed germination in the shade
Lee KP Lopez-Molina L (2012), Control of seed germination in the shade, in Cell Cycle, 11(24), 4489-4490.
Spatially and genetically distinct control of seed germination by phytochromes A and B
Lee KP Piskurewicz U Turečková V Carat S Chappuis R Strnad M Fankhauser C Lopez-Molina L. (2012), Spatially and genetically distinct control of seed germination by phytochromes A and B, in Genes & Development, 26(17), 1984-1996.

Collaboration

Group / person Country
Types of collaboration
Université de Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Pohang University of Science and Technology Korean Republic (South Korea) (Asia)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Palacky University Czech Republic (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
iGE3 Annual Meeting Talk given at a conference The role of the endosperm and genomic imprinting for the control of seed germination 13.11.2014 Geneva, Switzerland Lopez-Molina Luis;
Freie Universität Berlin, Dahlem Centre of Plant Sciences Individual talk The role of the endosperm and genomic imprinting for the control of seed germination 24.10.2014 Berlin, Germany Lopez-Molina Luis;
Institute of Genetics and Developmental Biology, Chinese Academy of Sciences Individual talk The role of the endosperm and genomic imprinting for the control of seed germination 19.09.2014 Beijing, China Lopez-Molina Luis;
11th Conference of the International Society for Seed Science, Changsha, China. Talk given at a conference The role of the endosperm and genomic imprinting for the control of Arabidopsis seed germination. 15.09.2014 Changsha, China Lopez-Molina Luis;
IPGSA 2013, International Conference on Plant Growth Substances Talk given at a conference Arabidopsis seed germination: the endosperm controls early embryonic growth 18.06.2013 Shanghai, China Lopez-Molina Luis;
Institute of Plant Biology, University of Zurich Individual talk Arabidopsis seed germination: the endosperm controls early embryonic growth 08.03.2013 Zurich, Switzerland Lopez-Molina Luis;
SWISSPLANT'13 Talk given at a conference The central role of the endosperm for the control of seed germination in Arabidopsis thaliana 30.01.2013 Meiringen, Switzerland Lopez-Molina Luis;
Invited speaker, Center for Novel Agricultural Products (CNAP) and Department of Biology, University of York (UK) Individual talk The central role of the endosperm for the light-dependet control of seed germination 11.12.2012 York, United Kingdom, Great Britain and Northern Ireland Lopez-Molina Luis;
Invited speaker, Centre for Research in Agricultural Genomics (CRAG) CSIC IRTA UAB UB Consortium Individual talk Revisiting phytochrome-dependent control of seed germination 08.06.2012 Barcelona, Spain, Spain Lopez-Molina Luis;
Plant development and environmental interactions Poster Spatially distinct phyB and phyA signaling pathways permanently interact for the light-dependent control of Arabidopsis seed germination 27.05.2012 Matera, Italy Lopez-Molina Luis;
Invited speaker, Department of Biology, Plant Biology, Université de Fribourg Individual talk Revisiting phytochrome-dependent control of seed germination 26.04.2012 Fribourg, Switzerland Lopez-Molina Luis;
SWISSPLANT'12 Poster Invited Speaker (I offered my oral presentation spot and presented a poster instead due to organisational issues) 18.01.2012 Meiringen, Switzerland, Switzerland Lopez-Molina Luis;
Invited speaker, Instituto de Biologia Molecular y Celular de Plantas – IBMCP Individual talk Holding On For a Successful Kick-Start: Control of Seed Germination in Arabidopsis 20.05.2011 Valencia, Spain , Spain Lopez-Molina Luis;
Invited speaker, Institute of Agricultural Sciences, ETHZ Individual talk Holding On For a Successful Kick-Start: Control of Seed Germination in Arabidopsis 03.05.2011 Zurich, Switzerland Lopez-Molina Luis;


Associated projects

Number Title Start Funding scheme
152660 Selected topics on the control of seed germination: light, temperature and dormancy 01.01.2015 Project funding
120866 An abscisic acid-induced developmental checkpoint in plant germination: Study of its genetic and molecular control 01.09.2008 SNSF Professorships

Abstract

In Arabidopsis it is well established that repression of seed germination in dormant seeds upon seed imbibition is an active process requiring de novo and constitutive synthesis of the phytohormone abscisic-acid (ABA). In this project proposal, we present preliminary results showing that dormant seeds constitutively express the gibberellic acid (GA)-response factor RGL2, a DELLA factor of the GRAS family recently shown to stimulate endogenous ABA synthesis. Unlike non-dormant seeds, dormant seeds are unable to down-regulate RGL2 expression (mRNA and protein) in response to GA. We propose to explore the hypothesis that de novo ABA synthesis is due to the constitutive accumulation of RGL2. Furthermore, our proposed experiments address the questions of how RGL2 constitutive expression is achieved and how dormancy-breaking treatments (e.g. stratification) down-regulate RGL2 expression.We also present a novel “seed coat bedding assay” that physically separates the seed coat and the embryo while still keeping active the repression of germination by the seed coat. This assay shows that the seed coat is a tissue producing diffusible signals necessary to prevent embryonic growth. Furthermore, the assay allows using seed coats of different genotypic backgrounds to genetically dissect the germination-repressing activities produced by the seed coat. We propose experiments aimed at identifying such diffusible signals as well as to test the hypothesis that the seed coat is an essential organ for ABA production to sustain ABA-dependent repression in dormant embryos.
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