Deep below the Arctic Ocean, some plants have adapted to photosynthesize in almost near darkness

Plants can grow with much less light than previously thought, according to a new study on tiny water-based organisms called microalgae that has been published in Nature Communications. The German-led team of researchers lowered light sensors into Arctic water to a depth of 164 feet (50 metres) to test how low light levels must become before plant life ceases to exist, with incredible results.

They found that plants were able to perform photosynthesis — the process in which their leaves convert sunlight into energy — with very little light indeed. Not only did the microalgae carry out this process at the lowest light levels ever recorded (just 0.04 micromoles of photons m⁻²/s⁻¹), this wasn't very far from what computer simulations predict to be the lowest light possible in any circumstances (0.01 micromoles of photons m⁻²/s⁻¹).

To put this in context, typical light conditions outside on a clear day in Europe are between 1,500-2,000 micromoles of photons m⁻²/s⁻¹ — that's more than 37,000-50,000 times the amount of light required by those Arctic microalgae. It is an amazing discovery that some plants are adapted to survive with so much less light.

This discovery offers several exciting possibilities for the field of plant Sciences:

1. Extended growing seasons

Many areas around the world receive too little sunlight because they are far from the equator and endure long winters, or are persistently covered by cloud. The UK is affected by cloud cover, for instance: in 2024 it is on the way to having one of the worst periods of total light hours since the 1900s (only the 1930s and early 1990s were worse).

Now that we know how little light is required for photosynthesis, scientists could develop crops that require much less light to thrive in such places by learning from these Arctic microalgae. By unlocking their genetic potential, many crops could benefit by using plant breeding or biotech approaches to alter them accordingly.

In particular, this could help to eke more out of short growing seasons and increase food production. Even in a relatively southerly place like the UK, breeding plants that can photosynthesise with less light would potentially increase crop yields.