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Small RNAs play a major role in the post-transcriptional regulation of gene expression in eukaryotes. Despite the evolutionary importance of streptophyte algae, knowledge on small RNAs in this group of green algae is almost non-existent. We used genome and transcriptome data of 34 algal and plant species, and performed genome-wide analyses of small RNA (miRNA & siRNA) biosynthetic and degradation pathways. The results suggest that Viridiplantae started to evolve plant-like miRNA biogenesis and degradation after the divergence of the Mesostigmatophyceae in the streptophyte algae. We identified two major evolutionary transitions in small RNA metabolism in streptophyte algae; during the first transition, the origin of DCL-New, DCL1, AGO1/5/10 and AGO4/6/9 in the last common ancestor of Klebsormidiophyceae and all other streptophytes could be linked to abiotic stress responses and evolution of multicellularity in streptophytes. During the second transition, the evolution of DCL 2,3,4, and AGO 2,3,7 as well as DRB1 in the last common ancestor of Zygnematophyceae and embryophytes, suggests their possible contribution to pathogen defense and antibacterial immunity. Overall, the origin and diversification of DICER and AGO along with several other small RNA pathway-related genes among streptophyte algae suggested progressive adaptations of streptophyte algae during evolution to a subaerial environment.
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http://dx.doi.org/10.1038/s42003-021-01933-5 | DOI Listing |
NPJ Biofilms Microbiomes
September 2025
GFZ Helmholtz Centre for Geosciences, Potsdam, Germany.
Eukaryotic algae-dominated microbiomes thrive on the Greenland Ice Sheet (GrIS) in harsh environmental conditions, including low temperatures, high light, and low nutrient availability. Chlorophyte algae bloom on snow, while streptophyte algae dominate bare ice surfaces. Empirical data about the cellular mechanisms responsible for their survival in these extreme conditions are scarce.
View Article and Find Full Text PDFNew Phytol
August 2025
Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna Biocenter, Vienna, 1030, Austria.
The ability of a cell to polarise, and direct cell growth or orient cell division, for example, is fundamental for the morphogenesis of multicellular organisms. A key molecular system for signalling cell polarity in diverse eukaryotes involves the RHO family of small GTPases. Since its origin in early eukaryotes, the RHO family has evolved independently in different lineages, and the plant-specific subfamily of RHO - RHO of plants (ROP) - was established in the streptophyte algal ancestors of land plants.
View Article and Find Full Text PDFCurr Biol
July 2025
Institute of Microbiology and Genetics, Göttingen Centre for Molecular Biosciences (GZMB), Campus Institute Data Science (CIDAS), Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany. Electronic address:
Over the last decade, collaborative efforts in plant evolutionary research have elucidated the phylogenetic relationships in the green plant lineage and provided insights into the emergence of land plants from a group of terrestrial and freshwater streptophyte algae. A foremost finding was that the genetic underpinnings of several key traits emerged much earlier than land plants - they were present in their streptophyte algal progenitors. Currently, the field is at a crossroads, transitioning from genomics-informed descriptions of streptophyte algae to a functional understanding of molecular mechanisms underlying their unique physiology, as well as to understanding their origin and evolution.
View Article and Find Full Text PDFPlant J
June 2025
Department of Applied Bioinformatics, Institute of Microbiology and Genetics, University of Goettingen, Goldschmidtstr. 1, Goettingen, 37077, Germany.
We computed co-expression networks from more than 2200 samples of nine species across 600 million years of divergent streptophyte evolution and infer that the streptophyte algal ancestors of land plants already had a remarkable fraction of the embryophytic stress response system. Despite its phytohormone-independent origin, homologs of all core components of the drought hormone abscisic acid (ABA) subnetwork are present, and we find that most are co-expressed in streptophyte algae and land plants; this subnetwork was thus co-opted in embryophytes by bringing it under the regime of ABA. The last common ancestor of embryophytes and Zygnematophyceae algae had ancient stress-responsive pathways, enabling it to face the stresses typical of the land environment - even before the origin of land plants - while evolution on land led to the adaptive refinement of these responses.
View Article and Find Full Text PDFNew Phytol
August 2025
Plant Physiology Department, Faculty of Mathematics and Natural Sciences, University of Rostock, Einsteinstr. 3, 18059, Rostock, Germany.
Oxygenic photosynthesis in streptophytic algae, such as Charophyceae, is often impeded by low CO levels in aquatic habitats. Consequently, many algal groups evolved a CO-concentrating mechanism (CCM). However, its presence in Charophyceae remains controversial.
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