3D-reconstructions of zygospores in Zygnema vaginatum (Charophyta) reveal details of cell wall formation, suggesting adaptations to extreme habitats.

Autor: Permann C; Department of Botany, University of Innsbruck, Innsbruck, Austria., Pichrtová M; Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic., Šoljaková T; Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic., Herburger K; Department of Botany, University of Innsbruck, Innsbruck, Austria.; Institute of Biological Sciences, University of Rostock, Rostock, Germany., Jouneau PH; Laboratoire Modélisation et Exploration des Matériaux, IRIG, CEA, Univ. Grenoble Alpes, Grenoble, France., Uwizeye C; Laboratoire de Physiologie Cellulaire et Végétale, CEA, CNRS, INRAE, Univ. Grenoble Alpes, Grenoble, France., Falconet D; Laboratoire de Physiologie Cellulaire et Végétale, CEA, CNRS, INRAE, Univ. Grenoble Alpes, Grenoble, France., Marechal E; Laboratoire de Physiologie Cellulaire et Végétale, CEA, CNRS, INRAE, Univ. Grenoble Alpes, Grenoble, France., Holzinger A; Department of Botany, University of Innsbruck, Innsbruck, Austria.
Jazyk: angličtina
Zdroj: Physiologia plantarum [Physiol Plant] 2023 Jul-Aug; Vol. 175 (4), pp. e13988.
DOI: 10.1111/ppl.13988
Abstrakt: The streptophyte green algal class Zygnematophyceae is the immediate sister lineage to land plants. Their special form of sexual reproduction via conjugation might have played a key role during terrestrialization. Thus, studying Zygnematophyceae and conjugation is crucial for understanding the conquest of land. Moreover, sexual reproduction features are important for species determination. We present a phylogenetic analysis of a field-sampled Zygnema strain and analyze its conjugation process and zygospore morphology, both at the micro- and nanoscale, including 3D-reconstructions of the zygospore architecture. Vegetative filament size (26.18 ± 1.07 μm) and reproductive features allowed morphological determination of Zygnema vaginatum, which was combined with molecular analyses based on rbcL sequencing. Transmission electron microscopy (TEM) depicted a thin cell wall in young zygospores, while mature cells exhibited a tripartite wall, including a massive and sculptured mesospore. During development, cytological reorganizations were visualized by focused ion beam scanning electron microscopy (FIB-SEM). Pyrenoids were reorganized, and the gyroid cubic central thylakoid membranes, as well as the surrounding starch granules, degraded (starch granule volume: 3.58 ± 2.35 μm 3 in young cells; 0.68 ± 0.74 μm 3 at an intermediate stage of zygospore maturation). Additionally, lipid droplets (LDs) changed drastically in shape and abundance during zygospore maturation (LD/cell volume: 11.77% in young cells; 8.79% in intermediate cells, 19.45% in old cells). In summary, we provide the first TEM images and 3D-reconstructions of Zygnema zygospores, giving insights into the physiological processes involved in their maturation. These observations help to understand mechanisms that facilitated the transition from water to land in Zygnematophyceae.
(© 2023 The Authors. Physiologia Plantarum published by John Wiley & Sons Ltd on behalf of Scandinavian Plant Physiology Society.)
Databáze: MEDLINE
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