With the ERC-consolidator grant â€œScattering and tapping on soft-hard-open nutsâ€ we elucidate how nature builds up hard and tough nutshells (seed coats) for packaging of the next generation â€“ the seed. The seed coat as enclosure of the developing embryo gives protection...
With the ERC-consolidator grant â€œScattering and tapping on soft-hard-open nutsâ€ we elucidate how nature builds up hard and tough nutshells (seed coats) for packaging of the next generation â€“ the seed. The seed coat as enclosure of the developing embryo gives protection in many different environments, including harsh conditions from dry to wet, from hot to cold and from short to very long periods. Nut-producing species have evolved a number of traits that facilitate dispersal by certain rodents and corvids and exclude other animals that act as parasites. The big nutritious food sources inside attracts and a hard shell outside enhances the probability of being buried in the soil than rather being cracked and eaten immediately.
To understand the remarkable hardness and toughness of the shells we dive deep into the micro-and nanostructure of these tissues and their chemistry. To do so we develop sample preparation techniques which enable to study the native tissues during the development from the soft to the hard state. Microspectroscopic approaches (FT-IR microscopy, nano-IR, Raman microscopy) are used to reveal the chemistry in context with the micro- and nanostructure and to become a complete picture also 3D- visualizations by X-ray tomography and fluorescence microscopy are applied. By including different nut species we aim to understand general and specific design principles of the nutshell and to derive structure-function relationship. Sampling at different developmental stages opens a view on the â€œproduction processâ€ (development) of the packaging structures. All the results together will inspire biomimetic material design as well as the optimized use of nutshell for new biomaterial developments. As nuts are more and more recognized as one of the most valuable, healthy natural food resources, nutshell will be available in increasing amounts as waste material.
\"In the beginning of the project we did a â€œscreeningâ€ of different nutshells to select the most interesting ones for in-depth analysis. Based on these data we come up with a new classification and we will summarize the different strategies of nature to build up these hard packaging structures in a review paper. By sampling at different time points during development we get insights into the \"\"fabrication\"\" of the nut shell, including cell shape and cell wall formation as well as impregnation with different chemical components from the soft to the hard state. For our in-depth analysis we had to develop and adopt sample preparation as well as microspectroscopic approaches to reveal chemistry, structure and nanomechanics of the native nut shell tissues. Different microtomy and ultramicrotomy approaches are applied and the results of microspectroscopic approaches are thousands of vibrational spectra, each a molecular fingerprint at one micro or nanoposition. Due to the multicomponent nature of our nutshells and the high number of spectra the analysis as well as the interpretation needs groundbreaking basic research and expertise. We made an important step forward by using different unmixing methods for the analysis of our Raman spectra (Prats Mateu et al. 2018a). The understanding of aromatics during laser exposure (Prats-Mateu et al. 2018b) as well as interpretation of vibrational modes (Bock et al. 2019) is the basic pre-requisite for analyzing and understanding our acquired nut-shell spectra. The most intriguing result so far was the discovery of a new cell type in the walnut shell, published recently in Advanced Science (Antreich et al. 2019). A polylobate unit cell, which is interlocked with 14 neighbors was visualized and proven by a set of methods, including x-ray tomography (see supplementary videos of the article: http://wordpress.bionami.at/2019/06/12/the-puzzle-of-the-walnut-shell/). The interlocked packing results in a significant increase in ultimate tensile strength, compared to â€œnormalâ€ polygonal found in pine seed coat.
â€¢ Prats-Mateu B, Felhofer M, de Juan A, Gierlinger N (2018a) Multivariate unmixing approaches on Raman images of plant cell walls: new insights or overinterpretation of results? Plant methods 14: 52
â€¢ Prats-Mateu B, Bock P, Schroffenegger M, Toca-Herrera JL, Gierlinger N (2018b) Following laser induced changes of plant phenylpropanoids by Raman microscopy. Scientific reports 8: 11804, doi 10.1038/s41598-018-30096-3
â€¢ Bock P, Gierlinger N (2019) Infrared and Raman spectra of lignin substructures: Coniferyl alcohol, abietin, and coniferyl aldehyde. Journal of Raman Spectroscopy 50 (6): 778-792, DOI: 10.1002/jrs.5588
â€¢ Antreich SJ, Xiao N, Huss JC, Horbelt N, Eder M, Weinkamer R, Gierlinger N (2019) The puzzle of the walnut shell: A Novel Cell Type with Interlocked Packing. Advanced Science, https://doi.org/10.1002/advs.201900644
A big challenge in biology and biomimetic research is to understand the design principles and physicochemical mechanism underlying the optimized biological systems as well as their developmental assembly. To tackle exactly these challenges the objectives of this project are threefold:
1) develop in-situ methods for in-depth characterization of seed dispersal units at the micro-and nano level
2) reveal the heterogeneity and common design principles by including different biological species and derive general structure-function relationships
3) follow in-situ growth, development, maturation and germination of seed coats
More info: http://bionami.at.