Comparative Analyses of the Self-Sealing Mechanisms in Leaves of Delosperma cooperi and Delosperma ecklonis (Aizoaceae)

Abstract

Within the Aizoaceae, the genus Delosperma exhibits a vast diversification colonizing various ecological niches in South-Africa and showing evolutionary adaptations to dry habitats that might include rapid self-sealing. Leaves of Delosperma react to external damage by the bending or contraction of the entire leaf until wound edges are brought into contact. A study of leaf morphology and anatomy, biomechanics of entire leaves and individual tissues and self-sealing kinematics after a ring incision under low and high relative humidity (RH) was carried out comparing the closely related species Delosperma cooperi and Delosperma ecklonis, which are indigenous to semi-arid highlands and regions with an oceanic climate, respectively. For both species, the absolute contractions of the examined leaf segments (“apex”, “incision”, “base”) were more pronounced at low RH levels. Independent of the given RH level, the absolute contractions within the incision region of D. cooperi were significantly higher than in all other segments of this species and of D. ecklonis. The more pronounced contraction of D. cooperi leaves was linked mainly to the elastic properties of the central vascular strand, which is approximately twice as flexible as that of D. ecklonis leaves.

Elastic and collapsible: current understanding of cell walls in succulent plants

“…Another disadvantage of CoMPP is the difficulty of isolating succulent tissues within a succulent organ, which is not feasible in most cases and requires whole organs. The latest technological developments include imaging techniques that allow for three-dimensional visualization of cell wall structure, composition, and connectivity, including serial-sectioning scanning electron microscopy (ssSEM; Oi et al , 2017 ; Harwood et al, 2020 , 2021 ; Antreich et al , 2021 ) among other high-resolution microscopy techniques ( Zeng et al , 2017 ; Haas et al , 2020 ), X-ray microcomputed tomography (X-ray microCT; Théroux-Rancourt et al , 2017 ; Earles et al , 2018 ), and magnetic resonance imaging (MRI; Malik et al , 2016 ; Hesse et al , 2020 ; Mylo et al , 2021 ). These methods have the potential to elucidate how succulent tissues are built and to reveal their anatomical complexity from a three-dimensional perspective.…”

Charting the twist-to-bend ratio of plant axes

“…Design x.4 : The succulent leaves of the genus Delosperma show an arrangement of centrally positioned vascular bundles combined with several peripheral individual bundles. The leaves of Delosperma cooperi are circular ( a .4) to oval ( b .4), whereas the leaves of Delosperma ecklonis have a triangular geometry ( d .4) [ 13 , 42 ]. With respect to table 2 the twist-to-bend ratios of a .4 and b .4 are approximately half the value of that of d .4.…”

Plant-inspired damage control – An inspiration for sustainable solutions in the Anthropocene

“…Diverse reactions dependent on the respective body plan of the plant species can be found after mechanical damage. Initially after damage, mostly physical responses cause rapid wound sealing and include (i) the deformation of the entire plant organ (Hesse et al, 2020;Speck et al, 2018), (ii) the tissue deformation in the wounded region (Anandan et al, 2018;Mylo et al, 2020), (iii) the squeezing of sealing cells into fissures (Busch et al, 2010) and (iv) the discharge of mucilage (e.g. cacti) or latex (e.g.…”