A research breakthrough has unearthed the genetic foundations that enabled macroalgae, or "seaweed," to evolve into multicellular organisms and increased the total number of sequenced macroalgal genomes from 14 to 124.
Macroalgae play a critical role in global climate regulation and ecosystems, and have a whole range of applications in biotechnology and eco-engineering, all of which are directly linked to their genomes. However, until now, not a lot has been known about their genomes.
To address this – in a first of its kind study – at the Technology Innovation Institute (TII), Dr. Alexandra Mystikou, Lead Researcher in our biotechnology team in Abu Dhabi, along with an international team of researchers, began investigating the evolution of macroalgal multicellularity through genomics. The goal was to provide valuable insight into the potential compounds and applications that different macroalgal species can offer across industries.
The research findings are now available to read in Dr. Mystikou’s paper: Macroalgal deep genomics illuminate multiple paths to aquatic, photosynthetic multicellularity, which has also recently been published in Molecular Plant, one of the top Cell Press, peer-reviewed, scientific journals.
Investigating macroalgal evolution
Macroalgae or “seaweed” are aquatic autotrophs that live in both fresh and seawater. They are complex multicellular organisms with distinct organs and tissues. This differentiates them from microalgae, which are microscopic and unicellular.
There are three main groups of macroalgae: red (Rhodophyta), green (Chlorophyta), and brown (Ochrophyta). Each independently evolved multicellularity at very different times and in very different environmental conditions. Rhodophytes and Chlorophytes both evolved multicellularity over a billion years ago, while Ochrophytes only became multicellular in the past 200,000 years.
In order to investigate the evolution of macroalgal multicellularity, we sequenced 110 new macroalgal genomes from 105 different species originating from fresh and saltwater habitats, in diverse geographies and climates, including the UAE.
A blueprint for building multicellular organisms
What we found were several metabolic pathways that distinguish macroalgae from microalgae, with some pathways potentially playing a role in the success of invasive macroalgal species.
Macroalgae acquired many new genes that are not present in microalgae on their road to multicellularity. For all three groups, key acquisitions included genes involved in cell adhesion (which enables cells to stick together), cell differentiation (which allows different cells to develop specialized functions), cell communication, and inter-cellular transport.
Distinct features were also identified between the macroalgal groups. For example, we observed much more diversity between different species of Rhodophyte, which evolved multicellularity first and have thus had longer to diverge. Meanwhile, Chlorophytes were found to share many genomic features with land plants, suggesting that these genes may have already been present in the last common ancestor of Chlorophytes and plants.
Overcoming obstacles and leveraging technology
A key challenge we faced was that since this was the first extensive genomic resource for macroalgae – with only four seaweed genomes publicly available when the project began – there were no references or specialized bioinformatics pipelines. As a result, a benchmarking study was undertaken, leading to the development of innovative approaches to address these challenges.
Technology also played a pivotal role in the project, with the team utilizing cutting-edge genome sequencing platforms, bioinformatics tools, and machine learning models to manage vast amounts of data and derive meaningful conclusions and discoveries.
Genome-wide mapping that translates to application
This newly created, extensive genome resource offers valuable insights into the potential compounds (both known and unknown) that these 110 different macroalgal species can produce and the hope is that it will serve as the basis for further research.
Having by no means exhaustively explored all that there is in these genomes, we are keen to examine some of their features in more detail, as well as sequence and analyze even more macroalgal genomes in the future.
In the near term, ongoing research into the genomic environmental adaptation of macroalgae will be prioritized, which is crucial for maximizing their potential benefits. In this research study, key genes that enable algae to adapt to extreme environments have been identified, such as those found in the UAE, and has predicted which species are likely to be climate change survivors, making them ideal candidates for industrial applications.
Dr. Mystikou along with her team at TII are currently working on microalgal and macroalgal bioprospection and applications. They are leveraging genomics to discover and develop compounds applicable across vital sectors such as pharmaceuticals, cosmetics, energy and nutrition, while also utilizing algae to address significant national challenges.