Modeling the nonlinear elastic behavior of plant epidermis

Abstract

Cell growth and organ development in plants are often correlated with the tensile behavior of the primary cell wall. To understand the mechanical behavior of plant material, various mechanical testing techniques have been employed, such as tensile testing of excised tissue samples. The onion (Allium cepa L.) epidermis has emerged as a model system for plant tissue mechanics. In this study, we performed tensile tests on strips of adaxial onion epidermis. While the tissue appeared stiffer in the direction along the major growth axis compared with the transverse direction, the tensile strength of tissue was not significantly different between the two orientations, indicating a nontrivial link between the cell wall and tissue mechanical anisotropy. Importantly, we observed the stress-strain behavior of the onion epidermis under tension to be highly nonlinear. Several hyperelastic models were fitted to the test data to evaluate their capacity to describe the nonlinear deformation of onion epidermis. The Yeoh hyperelastic model could successfully simulate the uniaxial tensile test data. This study suggests that accounting for nonlinearity in the deformation of the primary tissue may be essential for the accurate interpretation of mechanical test data, and a better understanding of the mechanics of the primary plant cell wall.Résumé : La croissance cellulaire et le développement des organes chez les plantes sont souvent corrélés au comportement en traction de la paroi cellulaire primaire. Afin de comprendre le comportement mécanique de la matière végétale, plusieurs tests mécaniques ont été réalisés, tels que l'essai de traction sur des échantillons de tissus excisés. L'épiderme de l'oignon (Allium cepa L.) est apparu comme un système modèle de la mécanique des tissus végétaux. Dans cette étude, les auteurs ont réalisé des essais de traction sur des bandes d'épiderme adaxial de l'oignon. Alors que le tissu semblait plus rigide le long de l'axe principal de croissance comparativement au sens transverse, les forces de traction du tissu n'étaient pas significativement différentes entre les deux orientations, indiquant l'existence d'un lien non négligeable entre la paroi cellulaire et l'anisotropie mécanique du tissu. Fait à noter, ils ont observé que le comportement de contrainte-déformation de l'épiderme de l'oignon placé sous tension était hautement non linéaire. Plusieurs modèles hyperélastiques ont été apposés aux données expérimentales afin d'évaluer leur capacité à décrire la déformation non linéaire de l'épiderme de l'oignon. Le modèle hyperélastique de Yeoh pouvait simuler avec succès les données de l'essai de traction uniaxiale. Cette étude suggère que la prise en compte de la non-linéarité de la déformation du tissu primaire peut être essentielle à l'interprétation exacte des données d'essais mécaniques et à une meilleure compréhension de la mécanique de la paroi cellulaire primaire des plantes. [Traduit par la Rédaction] Mots-clés : épiderme, mécanique des cellules végétales, élasticité non linéaire, hyperélasti...

Multiscale structural anisotropy in pulvinus motor organs of the sensitive plant Mimosa pudica

“…Thin sections were prepared for confocal microscopy by staining briefly (7-9 minutes) with 0.5 mg/ml propidium iodide (PI) in osmotically neutral mannitol. PI binds to cell wall pectin and is a common stain for live imaging of plant anatomical features (Bidhendi et al, 2020). After staining, tissues were rinsed briefly of unbound PI and then excited with a 543 nm Helium-Neon laser at 5% power.…”

“…10.1093/oxfordjournals.jbchem.a122421. Wang, Y. andLi, H. (2020). Bio-chemo-electro-mechanical modelling of the rapid movement of Mimosa pudica.…”

Biomechanics and hydraulics of Opuntia ficus-indica roots exposed to extreme drought

“…A r is the root cross-section area (m 2 ) and L r is the original length of the root (m). Δ L = L-L is the uniaxial displacement of the root (Bidhendi et al, 2019; Niklas, 1992). Finally, to calculate the amount of energy, that must be introduced into the system (i.e., plant root) to modify the biophysical properties of cell walls from cell to organ level, the strain energy (U) was calculated as follow (Niklas, 1992; Barrientos-Sanhueza et al, 2022): where σ is stress (MPa), ε is strain, and V r is root volume (m).…”

Plant biomechanics — an interdisciplinary lens on plant biology

“…One of the two types of fruit present on the same plant is dehiscent, the other indehiscent, offering an excellent opportunity to decipher the adaptive biomechanical morphologies that function as a bet-hedging strategy in the context of seed and fruit dispersal. At a much smaller scale than that of the organ, Bidhendi et al (2019) and Natonik-Białoń et al (2019) studied how the isolated epidermis of onion scales behaves under a mechanical load. Natonik-Białoń et al 2019characterized how the individual cells and the tissue behave under internal load applied through changes in turgor pressure.…”

“…Natonik-Białoń et al 2019characterized how the individual cells and the tissue behave under internal load applied through changes in turgor pressure. Bidhendi et al (2019), on the other hand, quantified the elastic and plastic deformation of the epidermis upon application of an external load using a tensile stretching device. They discovered that the mechanical behavior of the tissue is highly non-linear raising numerous questions about the interpretation of tensile test data obtained from primary plant tissues in general.…”