From the Soft to the Hard: Changes in Microchemistry During Cell Wall Maturation of Walnut Shells
| Autor: | Yannick M. Staedler, Nannan Xiao, Notburga Gierlinger, Peter Bock, Jürg Schönenberger, Sebastian J. Antreich |
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| Rok vydání: | 2019 |
| Předmět: |
0106 biological sciences
food.ingredient Juglans regia Pectin Shell (structure) Plant Science lcsh:Plant culture microchemistry 01 natural sciences Husk Cell wall 03 medical and health sciences chemistry.chemical_compound food Lignin lcsh:SB1-1110 Cellulose sclerenchyma 030304 developmental biology Original Research pectin 0303 health sciences Chemistry Confocal Raman microscopy Chemical engineering FTIR microscopic imaging cell wall lignification Secondary cell wall 010606 plant biology & botany Lumen (unit) |
| Zdroj: | Frontiers in Plant Science Frontiers in Plant Science, Vol 11 (2020) |
| ISSN: | 1664-462X |
| Popis: | The walnut shell is a hard and protective layer that provides an essential barrier between the seed and its environment. The shell is based on only one unit cell type: the polylobate sclerenchyma cell. For a better understanding of the interlocked walnut shell tissue, we investigate the structural and compositional changes during the development of the shell from the soft to the hard state. Structural changes at the macro level are explored by X-ray tomography and on the cell and cell wall level various microscopic techniques are applied. Walnut shell development takes place beneath the outer green husk, which protects and delivers components during the development of the walnut. The cells towards this outer green husk have the thickest and most lignified cell walls. With maturation secondary cell wall thickening takes place and the amount of all cell wall components (cellulose, hemicelluloses and especially lignin) is increased as revealed by FTIR microscopy. Focusing on the cell wall level, Raman imaging showed that lignin is deposited first into the pectin network between the cells and cell corners, at the very beginning of secondary cell wall formation. Furthermore, Raman imaging of fluorescence visualized numerous pits as a network of channels, connecting all the interlocked polylobate walnut shells. In the final mature stage, fluorescence increased throughout the cell wall and a remarkable fluorescent layer was detected towards the lumen in the inner part. This accumulation of aromatic components is reminiscent of heartwood formation of trees and is suggested to improve protection properties of the mature walnut shell. Understanding the walnut shell and its development will inspire biomimetic material design and packaging concepts, but is also important for waste valorization, considering that walnuts are the most widespread tree nuts in the world. |
| Databáze: | OpenAIRE |
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