Research

Research Priorities: Pattern formation, morphogens, small-RNA signals, stem cell homeostasis, differentiation

Marja Timmermans is a Dutch plant geneticist. One focus of her work is how leaves develop in plants at the molecular biological level.

Plant leaves are highly efficient solar panels that convert light energy into chemical energy via the production of sugars. Marja Timmermans studies the signalling events that coordinate gene activities in space and time at the shoot stem cell niche of the growing plant tip to understand how leaves develop and attain their distinctive flattened architecture. Her team was able to show that the so-called small RNAs function as mobile instructive signals in this process. Now they want to understand how small RNAs are able to move from cell to cell to trigger the formation of diverse developmental patterns.

Marja Timmermans describes her approach as follows: The formation of stable, precisely defined boundaries between two distinct cell fates is a fundamental feature of plant and animal development. Such cell fate boundaries coordinate the differentiation and growth of the tissue or organ. In this regard, development of flat leaf architecture poses an unusual and mechanistically challenging problem; namely, how to create a stable dorsoventral (top-bottom) boundary within the plane of a long and wide, but shallow structure?

Marja Timmermans and her team have shown that the positional information needed to establish dorsoventral polarity is provided in part by small RNAs. These generate – not unlike classical Morphogens – sharply defined domains of target gene expression via an intrinsic and threshhold-based readout of their mobility gradients. An obvious advantage of using small RNAs as mobile signals in plant development is their distinctive specificity and direct mode of action.

In addition, the scientists have shown that the mobility of small RNAs is regulated via mechanisms distinct from those controlling the movement of proteins. Small RNA mobility is gated at individual cell-cell interfaces. This creates the directionality which gives a pattern to their activity within stem cell niches. Her Team now seeks to understand how small RNAs move, what gates their mobility, and how the threshold-based readout is realized. They use a combination of theoretical and experimental approaches to understand how the regulatory network underlying dorsoventral polarity emerges during organogenesis at the shoot stem cell niche in space and time and, furthermore, how this controls the subsequent differentiation of specialized leaf cells.

Career

• since 2015 Alexander von Humboldt Professorship, University of Tübingen, Tübingen, Germany
• 2015-2018 Adjunct Professor, Cold Spring Harbor Laboratory, Cold Spring Harbor, USA
• 2009-2015 Professor, Cold Spring Harbor Laboratory, Cold Spring Harbor, USA
• 2005-2009 Associate Professor, Cold Spring Harbor Laboratory Cold Spring Harbor, USA
• 2001-2004 Assistant Professor, Cold Spring Harbor Laboratory, Cold Spring Harbor, USA
• 1998-2001 Independent Fellow, Cold Spring Harbor Laboratory, Cold Spring Harbor, USA
• 1996-1998 Postdoctoral Fellow, Yale University, New Haven, USA
• 1996 PhD, Rutgers University, New Brunswick, USA
• 1990-1996 Graduate Fellow, Waksman Institute, Rutgers University, New Brunswick, USA

Functions

• since 2020 Member, Scientific Board “DataPlant” (German research data infrastructure platform), Tübingen, Germany
• 2017-2019 Director, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
• 2011-2016 Member, Executive Committee, Maize Genetics, Ithaca, USA
• 2008-2015 Director, Independent Fellows Program, Cold Spring Harbor Laboratory, Cold Spring Harbor, USA

Projects

• since 2021 Applicant, Subproject “Regulation of Maize Shoot Apical Meristem Structure and Function”, Research Units (FOR), German Research Foundation (DFG), Germany
• since 2018 Head, Project “Specificity in intercellular small RNA mobility (C06)”, Collaborative Research Centres (SFB) 1101, DFG, Germany
• 2016 Leader, Project “Klimakammer Mais 1”, DFG, Germany
• 2016 Leader, Project “Klimakammer Mais 2”, DFG, Germany
• 2016-2019 Head, Project “Yield stability in dynamic environments”, Ministry of Science Baden-Württemberg, Stuttgart, Germany
• 2014-2017 Host, Project “A Comprehensive Study of the Maize Shoot Apex – Deciphering Genes Underlying Shoot Apical Meristem Allometry”, DFG, Germany
• 2013-2018 Member, Project “Genetic Networks Regulating Structure and Function of the Maize Shoot Apical Meristem”, National Science Foundation (NSF), USA
• 2008-2012 Member, Project “Genomic Analysis of Shoot Meristem Function in Maize” NSF, USA
• 2003-2008 Member, Project “Functional Analysis of Genes Involved in Meristem Organization and Leaf Initiation”, NSF, USA

Honours and Memberships

• since 2020 Member, German National Academy of Sciences Leopoldina, Germany
• 2020 Elected Member, Heidelberger Academy of Sciences, Heidelberg, Germany
• since 2018 Member, European Molecular Biology Organization (EMBO)
• 2015-2021 Alexander von Humboldt Professorship, Alexander von Humboldt-Stiftung, Bonn, Germany
• 2009 James M. and Cathleen D. Stone Award for Significant Research Achievements by a Junior Scientist, Cold Spring Harbor Laboratory, Cold Spring Harbor, USA
• 2007 Demerec-Kaufmann-Hollaender Fellowship in Developmental Genetics
• 2002-2004 Perkin Fellowship for Women in Science, Harry Perkins Institute, Nedlands, USA