Distributions of Silica and Biopolymer Structural Components in the Spore Elater of Equisetum arvense, an Ancient Silicifying Plant

Abstract

Equisetum species are primitive vascular plants that benefit from the biogenesis of silica bio-organic inclusions in their tissues and participate in the annual biosilica turnover in local eco-systems. As means of Equisetum reproduction and propagation, spores are expected to reflect the evolutionary adaptation of the plants to the climatic conditions at different times of the year. Combining methods of Raman and scanning electron microscopy and assisted with density functional theory, we conducted material spatial-spectral correlations to characterize the distribution of biopolymers and silica based structural elements that contribute to the bio-mineral content of the elater. The elater tip has underlying skeletal-like structural elements where cellulose fibers provide strength and flexibility, both of which are necessary for locomotion. The surface of the elater tips is rich with less ordered pectin like polysaccharide and shows a ridged, folded character. At the surface we observe silica of amorphous, colloidal form in nearly spherical structures where the silica is only a few layers thick. We propose the observed expansion of elater tips upon germination and the form of silica including encapsulated biopolymers are designed for ready dispersion, release of the polysaccharide-arginine rich content and to facilitate silica uptake to the developing plant. This behavior would help to condition local soil chemistry to facilitate competitive rooting potential and stem propagation.

Fungal pigments on paper: Raman and quantum chemistry studies of Alternaria Sp

“…biology [51]. Indeed, comparing our experimental and theoretical studies [26], a lignin-like component is likely to contribute into Raman activities at 1606 and 1700 cm -1 . In Supplementary information Fig.…”

“…Furthermore, Alternaria group is known to exhibit active lignin biochemistry [51]. In this contribution we used the results of our theoretical studies on a lignin-like structural segment reported previously [26].…”

“…To develop systematic diagnostics of fungal species at the molecular level we must distinguish different chromophores/pigments. Raman spectroscopy is a useful tool in this respect as the technique has a number of practical advantages: (1) it has sensitivity to detect responses from several molecules under light microscopic spatial resolution; (2) signals are characteristic of molecular structure; (3) it has an unprecedented specificity to excitation wavelength and to the polarization of light [23][24][25]; (4) Raman samples can be taken in vivo outside of a lab and sampling can be noninvasive; (5) Raman signals can be computed using Quantum Chemistry; (6) using results of Quantum Chemistry we may model orientational molecular distributions of chemical entities using observed Raman intensities when sampled at interfaces; and (7) sampling of Raman signals may be correlated with mass spectrometry and scanning electron microscopy [26]. The starting point in developing systematic Raman diagnostics is possible as signals are characteristic of molecular structure as in (2) above.…”

High‐speed video and plant ultrastructure define mechanisms of gametophyte dispersal

“…Some studies have moved beyond the above‐mentioned microscopy techniques to gain additional insights into gametophyte dispersal. The combination of SEM with chemical spectral techniques displays the distribution of elements and polymers involved in spore dispersal in the horsetail Equisetum (Volkov et al, 2019 ). 3D images can be obtained using X‐ray computed tomography and used to further understand soft tissue structure (Staedler et al, 2013 ).…”

“…Capsule walls and dehiscence grooves (Duckett and Pressel, 2019), arrangement of organs (Taylor et al, 2006;Whitaker et al, 2007;Zhang et al, 2020), water-absorbing potential (Taylor et al, 2006;Zhang et al, 2020), cavitation and gas bubbles (Hovenkamp et al, 2009;Poppinga et al, 2015) SEM Ultrastructure of surfaces (spores, dispersal organs, etc.) ~1,000,000× Standard or cryopreservation, environmental conditions Characteristics of diaspores (Pohjamo et al, 2006;Hovenkamp et al, 2009;Poppinga et al, 2015;Zanatta et al, 2016;Gómez-Noguez et al, 2017), sporophyte dispersal organs (Hovenkamp et al, 2009;Poppinga et al, 2015;Duckett and Pressel, 2019;Zhang et al, 2020), mechanism (Hovenkamp et al, 2009;Poppinga et al, 2015;Duckett and Pressel, 2019), elemental analysis (Volkov et al, 2019) TEM Subcellular structures ~2,000,000×…”