Self-Repair in Cacti Branches: Comparative Analyses of Their Morphology, Anatomy, and Biomechanics.

Max D Mylo,Olga Speck,Thomas Speck,Friederike Krüger

doi:10.3390/ijms21134630

Max D Mylo, Olga Speck + Show 2 more

Open Access

https://doi.org/10.3390/ijms21134630

Copy DOI

Abstract

Damage-repair is particularly important for the maintenance of the water-storing abilities of succulent plants such as cacti. Comparative morphological, anatomical, and biomechanical analyses of self-repair were performed on artificially wounded branches of Opuntia ficus-indica and Cylindropuntia bigelovii. Macroscopic observations, contrast staining, and lignin-proof staining were used to investigate morphological and anatomical responses after wounding at various time intervals. Two-point bending tests were repeatedly performed on the same branches under unwounded, freshly wounded, and healed conditions by using customized 3D-printed clamping jaws. Morphologically, both species showed a rolling-in of the wound edges, but no mucilage discharge. Anatomically, ligno-suberized peridermal layers developed that covered the wound region, and new parenchyma cells formed, especially in O. ficus-indica. In all samples, the wounding effect directly after damage caused a decrease between 18% and 37% in all the tested mechanical parameters, whereas a positive healing effect after 21 days was only found for C. bigelovii. Based on our data, we hypothesize a high selection pressure on the restoration of structural integrity in the wound area, with a focus on the development of efficient water-retaining mechanisms, whereas the concept of “sufficient is good enough” seems to apply for the restoration of the mechanical properties.

Highlights

Damage control is a crucial concept in the plant kingdom as it can preserve the functionality of a plant and ensure its survival
Damage control is often used as an umbrella term, covering the two aspects of damage prevention and damage management in the sense of complementary design concepts [1]
Self-repair can be subdivided according to the self-repair effects on the structural integrity in terms of morphological and anatomical wound reactions and on mechanical integrity in the sense of restoring the original mechanical performance of selected parameters after the healing of an injury

Summary

Introduction

Damage control is a crucial concept in the plant kingdom as it can preserve the functionality of a plant and ensure its survival. Plants can deal with existing damage in various ways, such as shedding old, injured, or no longer needed organs (so-called “abscission”) [2,3] or by using their self-repair ability to restore injured tissues and organs [4,5]. The latter is generally divided into an initial, rapid, self-sealing phase that functionally repairs the wound, protects the plant against serious water loss and pathogen invasion (bacteria, fungi, spores, etc.), and impedes further fissure propagation. In latex-bearing plants, the chemical coagulation of latex immediately after injuries has been shown to play a role in the recovery of tensile strength [8]

Results

Discussion

Conclusion