Linking mechanics and endoreduplication with tissue folding

Project Information

MendoFold

Grant agreement ID: 890883

DOI

10.3030/890883

Project closed

EC signature date 4 March 2020

Start date 1 June 2020

End date 25 January 2023

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 203 852,16

EU contribution

€ 203 852,16

Coordinated by

SVERIGES LANTBRUKSUNIVERSITET
Sweden

Periodic Reporting for period 1 - MendoFold (Linking mechanics and endoreduplication with tissue folding)

Reporting period: 2020-06-01 to 2022-05-31

Summary of the context and overall objectives of the project

Endoreduplication is a complex process that regulates cell size, but its molecular mechanism is not well-established. The relationship between endoreduplication and cellular regulators of cell growth, such as auxin, cell wall remodeling, and mechanical stress in plants, remains unclear. Understanding these topics is important for academic research and breeding, as it could help us improve crop yields, develop new plant-based products, and create more sustainable agricultural practices. Ultimately, these knowledges could also help to address global challenges like food security and climate change.
To tackle these questions, the MSCA project 'Linking mechanics and endoreduplication with tissue folding' aims to elucidate the molecular mechanisms of tissue folding in plants. The project focuses on three objectives: (1) investigating the role of endoreduplication in Arabidopsis apical hook development, (2) understanding how endoreduplication mediates hormone signals to establish differential growth in the apical hook, and (3) studying how endoreduplication regulates cell growth via cell wall modification and signaling at the convex side of the apical hook. The beneficiaries of this research are interested in discovering the integrated molecular pathway from hormone to cell growth via endoreduplication and cell walls.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Our study aimed to investigate the relationship between endoreduplication and cell size regulation through genetic, cell biological, and physiological experiments. Using a simple system of hypocotyl bending, we identified an integrative signaling pathway that explains how endoreduplication regulates cell size. Our key findings include: (i) Establishing a connection between nuclear DNA content control via endoreduplication and cell size regulation through the mechano-chemical properties of the extracellular matrix, specifically the cell wall in plants. (ii) Demonstrating that disrupting the endoreduplication machinery leads to the stiffening of the cell wall by increasing pectin methylesterification through the upregulation of the ERF115 family of AP2 transcription factors' expression. (iii) Showing that mechano-chemical changes due to the reduction of endoreduplication are transmitted by cell wall integrity kinase THESEUS1, ultimately leading to growth repression. (iv) Using the Arabidopsis hypocotyl bending system, we illustrate how asymmetric hormonal responses spatially pattern endoreduplication, resulting in differential growth regulation.
Despite the century-old recognition of the correlation between cell size and ploidy, Theodor Boveri's sea urchin experiments did not reveal the underlying mechanism. Our study presents a previously unknown mechanism that links ploidy with the control of cell size, offering an explanation for the enigmatic role of endoreduplication in morphogenesis. Our results have far-reaching implications for the robustness of development, the integration of growth regulators and mechanics in cell size control, and compensatory mechanisms that explain how organs robustly change and acquire their shapes.
The research project has resulted in a paper published in the prestigious Science family journal, Science Advances. The findings have been disseminated through various platforms, including the hosting website, ResearchGate, and Twitter. Furthermore, our results have inspired related research on other species, such as aspen, to explore their breeding potential. We anticipate further collaboration with biotechnology companies to promote the translation of our research.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

To date endoreduplication was widely thought to explain cell size and yet no linear correlation was found leading to questions regarding the role endoreplication played in organ growth. Our work by providing a mechanistic basis for the role of endoreplication in cell size control provides a new insight into the role of endoreplication and provides a conceptual platform for even non-plant systems to evaluate the role of endoreplication in organ size control thus going beyond state of the art in the area of cell size control.
The control of cell size is a fundamental question in biology but also of great interest in biotechnology from biomass perspective. These results are now available to Swetree technologies (STT) for possible exploitation for commercial purposes which could contribute to development of plants with higher biomass which if commercialized could be of high economic value for forestry in Scandinavian and Baltic countries which could create new jobs and potentially generate value for the company. If plants with greater biomass would be generated, these would contribute to sustainable forestry.
The project has provided training to the Marie-Curie fellow (Dr. Yuan Ma) and established his credentials as an attractive candidate for future role as independent group leader. There have been also interviews at prestigious Chinese universities for position of group leader. As a direct consequence of this work, postdoctoral fellow has been offered continuation at SLU.

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