Portrait photo of Laura Bacete standing in front of a waterfall Did you know that every second, plants produce 3,000 tons of cellulose, a key component of their cell walls? These walls play a crucial role in plant growth, adaptation to environmental conditions, and ultimately, in sustaining life on our planet. Furthermore, cell walls are essential for food production, clothing (cotton), wood, and even bioenergy. And they are renewable, climate-friendly, and naturally produced, making them crucial in the fight against climate change. In my research group, we want to know more about this fascinating plant structure, especially about the dynamic processes that allow it to adapt to changing conditions.

The cell wall is a complex network of carbohydrates and proteins that plays a crucial role in plant growth and adaptation to environmental conditions. The maintenance of cell wall integrity is essential for regulating the functional integrity of cell walls during development and stress. Plant cell wall integrity monitoring systems constantly survey the status of cell walls and initiate a series of responses when they are altered. Interestingly, plant cell wall integrity seems to be related to adaptation to challenging environments, since some cell wall mutants are more resistant to certain stresses.A 3-D illustration demonstrating the importance of cellulose for circular economy: trees of different size are displayed on the left side of a circle, fields and gras loan in the middle above a root network and circle of woody parts in the bottom part of the circle; on the right upper part a house, emissions and cloads are illustrated and centrally a white circle. “The importance of cellulose for circular economy”. Image created with Midjourney text-to-image AI.

Understanding the mechanisms behind cell wall integrity monitoring and response is a key area of research in our lab. Time and dynamics are the keywords that define our research group’s approach to cell walls. We are interested in understanding how cell wall integrity is regulated over time and how it responds to changes in the environment. By studying these dynamic processes, we aim to uncover the mechanisms that govern plant growth and development and pave the way for innovative solutions that benefit agriculture and the environment. Specifically, we explore the following research interests:

  • Understanding the relationship between cell wall composition and mechanical characteristics: We investigate how the composition of cell walls changes during plant development and interaction with the environment and how these changes affect their mechanical characteristics.
  • Defining the meaning of cell wall integrity: We explore the homeostasis of plant cell walls in the context of plant growth, adaptation, and response to environmental stresses.
  • Understanding how environmental stresses impact cell wall homeostasis: We study how environmental stresses, such as drought and pathogen attacks, affect cell wall homeostasis.
  • Investigating how the plant integrates cell wall information into developmental processes: We explore how the plant integrates information about cell wall composition and mechanical properties into its developmental processes, such as cell cycle progression.Schematic 3D illustration of the primatry plant cell wall with cellulose fibres illustrated as thick green tubes, pectins as yellow thinner lines twinin on top and within of the cellulose network, hemicellulose displayed as light blue shorter lines is intertwining between the cellulose fibres and below are proteins displayed as rounded structures connecting the cell wall with the plasmamembraneSchematic illustration of the primary plant cell wall and its key components. The cell wall is composed of cellulose, hemicellulose, and proteins, including the ectodomains of cell wall integrity (CWI) sensors, which play a crucial role in monitoring cell wall’s functional integrity.

Our lab employs a range of cutting-edge technologies to achieve our research goals. These include:

  • Brillouin and confocal microscopies: We use these imaging techniques to visualize changes in cell wall composition and mechanical properties.
Two photos displaying the set up of a Brillouin microscope next to each other on top and a schematic work flow describing illustrated below from laser excitation to data processing and analaysisBrillouin microscopy, a non-invasive imaging technique used to visualize changes in the mechanical properties of plant cell walls. It works by using laser light to probe the sample, which scatters light at different frequencies due to acoustic vibrations. By analyzing the frequency shift in the scattered light, the mechanical properties of the sample, such as stiffness and elasticity, can be determined.
  • Biochemical analysis: We use various biochemical analysis techniques, including GC/LC-MS and FTIR, to investigate the chemical composition of cell walls.
  • Molecular biology: We use various molecular biology techniques such as cloning, qRT-PCR, and RNAseq to investigate gene expression patterns related to cell wall integrity.
  • Cell wall fractionation and glycome profiling: We use these techniques to analyze the polysaccharides and proteins present in plant cell walls.
  • Study of signaling cascades: We explore the various signaling pathways involved in cell wall integrity monitoring and responses, especially hormone pathways (jasmonic, salicylic and abscisic acid) and pattern-triggered immunity-related responses (Ca2+ input, MAPK phosphorylation, ectopic lignin deposition, etc.).
Four Arabidopsis roots are displayed next to each other: the cell wall is coloured in blue and the inner part in magenta; the cell wall of the left root looks like a continouse line, while the one of two middle roots displays several holes and deformations; the cell wall of the right root looks thinner than the first one but not as strongly affected like the middle onesActivation of signalling cascades in Arabidopsis thaliana roots under different cell wall stresses. Confocal microscopy picture. From left to right: mock, isoxaben (cellulose biosynthesis inhibitor), osmotic stress and isoxaben+osmotic stress. Picture by Julia Schulz, Thorsten Hamann’s lab, NTNU (Norway).
  • Analysis of traits of agronomical interest: These include resistance to biotic (pathogens) and abiotic (drought, temperature, etc.) stresses, saccharification, biomass production, etc.
  • Computational modelling: We use different models (logical, finite-elements, etc.) to integrate our different data into models that enable us to analyse and predict cell wall behaviour.

Our lab is committed to using multidisciplinary approaches and novel methodologies to solve complex problems in plant research. Our research has far-reaching implications, including improving crop yields, creating new bio-based materials, and developing sustainable energy sources.Illustration of the Laura Bacete's multidisciplinary research approach displaying the different components involved Generating knowledge through data integration. Our multidisciplinary approach combines different data sources, which must be integrated to obtain a complete understanding of cell wall integrity. We employ computational models for effective data integration.

Selected publications:

Bacete, L., Schulz, J., Engelsdorf, T., Bartosova, Z., Tichá, T., Vaahtera, L., Yan, G., Gerhold, J., Øvstebø, C., Gigli-Bisceglia, N., Margueritat, J., Kollist, H., Dehoux, T., McAdam, S.A.M., Hamann., T. (2022) THESEUS1 modulates mechanical characteristics of cell walls and abscisic acid production in Arabidopsis thaliana. PNAS, 119 (1) e2119258119. DOI: 10.1073/pnas.2119258119.

  • One of the first applications of Brillouin Microspectroscopy in plants. We used this novel technique to study changes in biophysical characteristics of A. thaliana cell walls in response to cell wall damage and hyperosmotic pressure conditions.
  • To complement the Brillouin data, we studied downstream signaling processes mediated by phytohormones quantified using LC-MS/MS.
  • By integrating these results, we have developed a model explaining how a plant cell could generate specific responses to either cell expansion and shrinkage, based on interactions between the plant cell wall and plasma membrane.

Molina, A., Miedes, E., Bacete, L., Rodríguez, T., Mélida, H., Denancé, N., Sánchez-Vallet, A., Rivieré, M.P., López, G., Freydier, A., Bartel, X., Pattathil, S., Hahn, M. and Goffner, D. (2021) Arabidopsis cell wall composition determines disease resistance specificity and fitness. PNAS 118(5). DOI: 10.1073/pnas.2010243118

  • Interdisciplinary work using mathematical modelling and biochemical analysis to link Arabidopsis thaliana mutants with alterations in cell wall composition to improvement in resistance to biotic / abiotic stress.

Bacete, L., Miedes, E., Mélida, H., López, G., Denancé, N., Marco, Y. and Molina, A. (2020) ARABIDOPSIS RESPONSE REGULATOR 6 (ARR6) affects cell wall composition and mediates resistance to Plectosphaerella cucumerina and Ralstonia solanacearum. MPMI 33(5). DOI: 10.1094/MPMI-12-19-0341-R.

  • ARR6 was believed to act exclusively as a mediator of the plant’s hormonal responses. However, in this work we demonstrated ARR6 is also involved in the control of cell-wall composition and disease resistance, which stated the role of the plant cell wall in the modulation of specific immune responses.
  • Selected as Editor’s Pick for September 2020 issue of MPMI Journal.
  • Top cited paper in MPMI Journal during 2020.

Mélida, H., Bacete, L., Ruprecht, C., Rebaque, D., Del Hierro, I., López, G., Bunner, F., Pfrengle, F. and Molina, A. (2020). Arabinoxylan-oligosaccharides act as Damage Associated Molecular Patterns in plants regulating disease resistance. Front. Plant. Sci. 11, 1210. DOI: 10.3389/fpls.2020.01210.

  • Continuation of the research done during my PhD.
  • Using cell wall fractions extracted from the arr6 mutant, we were able to identify an arabinoxylan pentasaccharide with strong immunomodulatory activity.
  • In this work, we propose 33-α-l-arabinofuranosyl-xylotetraose (XA3XX) as a hemicellulose-derived DAMP triggering strong immune responses in Arabidopsis thaliana and enhancing crop disease resistance.

Bacete, L., Mélida, H., Miedes, E. and Molina, A. (2018) Plant cell wall-mediated immunity: cell wall changes trigger disease resistance responses. Plant J., 93, 614. DOI: 10.1111/tpj.13807

  • State-of-science review about the prominent role of plant cell wall in defense to pathogens.
  • Ranked in the top 20 most downloaded articles in The Plant Journal during 2018.