Morphology and Anatomy of Branch–Branch Junctions in Opuntia ficus-indica and Cylindropuntia bigelovii: A Comparative Study Supported by Mechanical Tissue Quantification

Mylo, Max D.; Hesse, Linnea; Masselter, Tom; Leupold, Jochen; Drozella, Kathrin; Speck, Thomas; Speck, Olga

doi:10.3390/plants10112313

Open AccessArticle

Morphology and Anatomy of Branch–Branch Junctions in Opuntia ficus-indica and Cylindropuntia bigelovii: A Comparative Study Supported by Mechanical Tissue Quantification

by

Max D. Mylo

^1,2,*

,

Linnea Hesse

^1,2,

Tom Masselter

¹,

Jochen Leupold

³,

Kathrin Drozella

⁴

,

Thomas Speck

^1,2,5

and

Olga Speck

^1,2

¹

Plant Biomechanics Group @ Botanic Garden, Faculty of Biology, University of Freiburg, Schänzlestraße 1, D-79104 Freiburg, Germany

²

Cluster of Excellence livMatS @ FIT—Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, D-79110 Freiburg, Germany

³

Department of Diagnostic and Interventional Radiology, Medical Physics, Medical Center—University of Freiburg, Faculty of Medicine, University of Freiburg, Killianstraße 5a, D-79106 Freiburg, Germany

⁴

Faculty of Environment and Natural Resources, Bertoldstraße 17, D-79098 Freiburg, Germany

⁵

Freiburg Materials Research Center (FMF), University of Freiburg, Stefan-Meier-Straße 21, D-79104 Freiburg, Germany

^*

Author to whom correspondence should be addressed.

Plants 2021, 10(11), 2313; https://doi.org/10.3390/plants10112313

Submission received: 2 September 2021 / Revised: 6 October 2021 / Accepted: 21 October 2021 / Published: 27 October 2021

(This article belongs to the Special Issue Periderm (Cork) Tissue Development in Plants)

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Abstract

The Opuntioideae include iconic cacti whose lateral branch–branch junctions are intriguing objects from a mechanical viewpoint. We have compared Opuntia ficus-indica, which has stable branch connections, with Cylindropuntia bigelovii, whose side branches abscise under slight mechanical stress. To determine the underlying structures and mechanical characteristics of these stable versus shedding cacti junctions, we conducted magnetic resonance imaging, morphometric and anatomical analyses of the branches and tensile tests of individual tissues. The comparison revealed differences in geometry, shape and material properties as follows: (i) a more pronounced tapering of the cross-sectional area towards the junctions supports the abscission of young branches of C. bigelovii. (ii) Older branches of O. ficus-indica form, initially around the branch–branch junctions, collar-shaped periderm tissue. This secondary coverage mechanically stiffens the dermal tissue, giving a threefold increase in strength and a tenfold increase in the elastic modulus compared with the epidermis. (iii) An approximately 200-fold higher elastic modulus of the vascular bundles of O. ficus-indica is a prerequisite for the stable junction of its young branches. Our results provide, for both biological and engineered materials systems, important insights into the geometric characteristics and mechanical properties of branching joints that are either stable or easily detachable.

Keywords: Opuntioideae; abscission; cacti; magnetic resonance imaging; periderm formation; tissue tensile testing

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MDPI and ACS Style

Mylo, M.D.; Hesse, L.; Masselter, T.; Leupold, J.; Drozella, K.; Speck, T.; Speck, O. Morphology and Anatomy of Branch–Branch Junctions in Opuntia ficus-indica and Cylindropuntia bigelovii: A Comparative Study Supported by Mechanical Tissue Quantification. Plants 2021, 10, 2313. https://doi.org/10.3390/plants10112313

AMA Style

Mylo MD, Hesse L, Masselter T, Leupold J, Drozella K, Speck T, Speck O. Morphology and Anatomy of Branch–Branch Junctions in Opuntia ficus-indica and Cylindropuntia bigelovii: A Comparative Study Supported by Mechanical Tissue Quantification. Plants. 2021; 10(11):2313. https://doi.org/10.3390/plants10112313

Chicago/Turabian Style

Mylo, Max D., Linnea Hesse, Tom Masselter, Jochen Leupold, Kathrin Drozella, Thomas Speck, and Olga Speck. 2021. "Morphology and Anatomy of Branch–Branch Junctions in Opuntia ficus-indica and Cylindropuntia bigelovii: A Comparative Study Supported by Mechanical Tissue Quantification" Plants 10, no. 11: 2313. https://doi.org/10.3390/plants10112313

APA Style

Mylo, M. D., Hesse, L., Masselter, T., Leupold, J., Drozella, K., Speck, T., & Speck, O. (2021). Morphology and Anatomy of Branch–Branch Junctions in Opuntia ficus-indica and Cylindropuntia bigelovii: A Comparative Study Supported by Mechanical Tissue Quantification. Plants, 10(11), 2313. https://doi.org/10.3390/plants10112313

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Morphology and Anatomy of Branch–Branch Junctions in Opuntia ficus-indica and Cylindropuntia bigelovii: A Comparative Study Supported by Mechanical Tissue Quantification

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