Microalgae proves to possibly be the oldest organism exploited by the Biotech industry. Now a mass research collaboration from Wisconsin (US), Cologne (Germany), Toulouse (France) and Norwich (UK) amongst others have published in PNAS that the microalgal genes needed for bacterial and fungal symbiosis were originally present before the transition of ancient plants to land.

The transition of plants to land from the ocean has been shown to have occurred in the early Devonian period around 450 millions years ago, paving a way for Metazoans (animals) to also colonize the barren landmasses. Green algae (Charophyta and Chlorophyta) can exist freely in water-masses, whereas land plants (Embryophyta) require adaptations for vascularisation and root support in order to thrive. For a much more in depth understanding of the current phylogenetic relationships in plant evolution check out this review by Leliaert et al. (here).

Algal Types

The two main groups of Green Algae – Chlorophyta and Charophyta – can exist freely in water, whereas Embryophyta (Land Plants) required symbiotic adaptations to allow them to colonize land soils.

Fossil records have since revealed that extinct species of arbuscular mycorrhizal (AM) spores were present around the same time. Since these fungi are a crucial group of symbiotes for embryophytes, such as flowering plants (Angiosperms), to be able to colonize soils and take up nutrients (e.g. Phosphorus, Sulfur and Nitrogen), this suggested that perhaps the genes required for such fungal symbiotic relationships were already present in plants long before this transition to land took place.

Now, a team assembled from the John Innes Centre in Norwich, University of Wisconsin-Madison, LRSV at the University of Toulouse, and the Cologne Biocenter have established this is indeed the case. Funded by the UK Biotechnology and Biological Sciences Research Council (BBSRC) and the US based National Science Federation, this international team has shown that the necessary genes needed for this transition in fact existed in ancient microalgal species before the rise of land plants (Embryophyta) and the later evolving Angiosperms (flowering vascular plants).

Published in the Proceedings of the National Academy of Sciences (PNAS), the research team concluded that the key genes for symbiosis and pre-cursors for downstream genes (for establishing roots etc.) evolved long before the existing of Embryophytes. A phylogenetic analysis of 259 transcritomes and 10 algal and basal land plants showed that the key gene in question  – a calcium and calmodulin-dependent protein kinase (a specific type of CDK regulator) – and its subsequent downstream genes associated with symbiosis appeared in a evolutionary step-wise manner, occurring first in extinct algal species (Chlorophytes).

Schematic represen- tation of the green lineage. Light blue: chlorophytes and basal charophytes; dark blue: advanced charophytes. Green bars on the left indicate the actual number of transcriptomes and genomes included in the extended dataset used in this study. (B) Schematic representation of the symbiotic genes.

Schematic representation of the green lineage. Light blue: chlorophytes and basal charophytes; dark blue: advanced charophytes. Green bars on the left indicate the actual number of transcriptomes and genomes included in the extended dataset used in this study. (B) Schematic representation of the symbiotic genes.

In Angiosperms, calcium regulation by CCaMDK have become a crucial regulator of the developmental process, as well as being responsible for the maintenance of bacterial/fungal symbioses. Since these CCaMDK regulators have therefore been shown to have already existed in Oceanic microalgae, this could be one reason behind their popularity in the biotech industry – i.e. they have an ancient mechanism to resist abiotic stresses (e.g. pathogentic attack or extreme climatic changes), making them valuable assets for research.

CCaMDK Regulators are crucial in Angiosperm (flowering plant) development, establishment of symbiotic relationships with A funghi and also help the plant resist biotic and abiotic stresses. (Source: Harper & Harman - Nature Reviews Molecular Cell Biology 6, 555-566 doi:10.1038/nrm1679)

CCaMDK Regulators are crucial in Angiosperm (flowering plant) development, establishment of symbiotic relationships with AM fungi and helping the plant resist biotic and abiotic stresses. (Source: Harper & Harman – Nature Reviews Molecular Cell Biology 6, 555-566 doi:10.1038/nrm1679)

Indeed, the exploitation of microalgae by Biotechs is quite impressive, with a diverse range of applications – from biofuels (here), to Omega-3 oil dietary supplements (e.g. Simris-Alg) to a source of textile ink for fashion designers (i.e. the Berlin based Algaemy project from Blond & Bieber).

So, algae are mighty old and amazingly versatile, and despite their pre-historic un-plant like forms, they are actually incredibly important to the biotech world.

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