The evolution of photosynthesis represents one of the key biological innovations responsible for the rise of complex life on planet Earth. Dr Tanai Cardona from Imperial College London recently published a review in Open Biology that challenges common myths in this field. We asked him a few questions about his work and what’s next in his career.




Tell us about yourself and your research?
I grew up on the Caribbean coast of Colombia, in a place called Montería. I travelled to Bogotá to study biology and there I became very interested in photosynthesis. After graduating, I went to Sweden to do my PhD in photosynthesis research at Uppsala University. After that, I spent two years at the CEA in Paris for my postdoc, before moving to the UK seven years ago. I am in the lab of Prof. A. William Rutherford FRS at Imperial College. I must say that 15 years since leaving Colombia, my love for photosynthesis research has only grown. I have the privilege now to lead an independent research programme to study the evolution of photosynthesis and photosynthetic reaction centres. Photosynthetic reaction centres are nature’s solar cells. These molecular machines are so amazingly ancient, yet so structurally and functionally complex, that I can never stop wondering: “how did these intricate machines originate? How did they evolve? When exactly?” I want to solve these questions at the greatest level of detail possible, that is, at the atomic level.


What is your article about and what are the main points readers should take from it?
The article is a critical assessment of the fundamental principles that underpin the study of the evolution of photosynthesis. There are two types of photosynthesis: oxygenic and anoxygenic photosynthesis. Oxygenic photosynthesis uses light to extract electrons from water, releasing oxygen as a by-product. Anoxygenic photosynthesis cannot split water and does not release oxygen. The importance of oxygenic photosynthesis for the evolution of life can hardly be overemphasised. It represents one of the key innovations that transformed Earth and paved the way for the rise of complex life.


It is universally accepted that anoxygenic photosynthesis is the more primitive type and that it gave rise to oxygenic photosynthesis. There is currently an unquestionable belief that this is indeed the case. This is important because our best scenarios for the evolution of life and Earth during the first half of the plant’s history depend on when photosynthesis originated and on when oxygen becomes available to life for the first time. At the beginning I had no reason to doubt this, but the closer I looked at the available data, the more I found inconsistencies and contradictions. My own research showed that the traditional view has no support, or that at the very least it was not accurate enough. I started to wonder, “Where does the confidence in this traditional view come from when all the evidence has been ambiguous, at best, or paradoxical, at worst?” I started to trace the history of the subject and discovered that this traditional view emerged from speculative commentary long before we understood the process well enough. So, I wanted to debunk some of the mythology that has built up around the subject and provide a new framework for the study of the evolution of photosynthesis. This new framework is better supported by multiple independent lines of evidence and is informed by our extensive understanding of photosynthesis today. It clarifies ambiguities, dispels paradoxes, and has more explanatory power. I think it is a big deal, text-book rewriting stuff.


The main points I would like the reader to take away, especially younger audiences, is that there are fascinating stories yet to be told on this fundamental topic. That there is a lot of scope for new research and new views. And finally, that trying to solve the puzzle of why life is the way it is can be an exciting and rewarding career endeavour.


Your review received good attention via; as a researcher, how have you found preprint servers helpful?
I am a huge advocate of open science. I upload all of my articles into a preprint service and try to engage with the community online via Researchgate, a science blog, and Twitter. I share unpublished data, openly discuss topics of interest in my field, and try to provide commentary and feedback on preprints that are within my expertise. I have found the preprint service very useful, both as a dissemination tool and as a way to receive feedback from other scientists before the paper is finally published.


Why did you submit to Open Biology and how was your experience publishing with Royal Society Publishing?
There were several reasons behind my decision to submit to Open Biology. The most important one is that Open Biology explicitly encourages the submissions of critical reviews. Flexibility in the submission format and structuring of the manuscript were also very important. The fact that it is published by the Royal Society was also something that I liked. My experience was good and smooth, the flexibility on submission format made the process more convenient than other journals with stricter formatting rules.


What’s next for you?
As an early-career scientist, my main objective at the moment is to consolidate my independence and to take the necessary steps towards establishing a research group. So I am currently working towards getting a tenured position. That brings some uncertainty, of course. Having said that, I have a few ongoing interesting projects. For example, I have a project that combines computational and lab-based approaches to reconstruct ancestral forms of photosynthesis. I want to experimentally test some of the predictions on the evolution of photosynthesis that are derived from my research. This project is funded by the Leverhulme Trust.


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Image credits:

1 – Tanai Cardona, Imperial College London.

2 – Molecular structures of ‘nature’s solar cells’, Tanai Cardona.


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