Plants have an incredible knack for greening and flowering in sync with the seasons. We've been trying to figure out how they do it for years, and scientists have now uncovered evidence that memory is involved. Of course, we aren't talking about memories stored in neurons. It's something much stranger.
Misfolded proteins called prions — which lead to personality changes, dementia and death in humans — may serve as a type of long-term memory in plants. That's the fascinating possibility raised by a new study in the Proceedings of the National Academies of Sciences, which shows that a plant protein involved in responding to light and temperature may have shapeshifting, prion-like powers, allowing it to form environmental memories that can distinguish a single cold night from a shift in seasons.
Prions are proteins that can change their shape and induce shape changes in other proteins. In most cases, a protein needs to stick to a specific conformation in order to function, which is why prions trigger all sorts of horrible diseases when they infect otherwise healthy humans. Rare and fatal neurodegenerative disorders, including Creutzfeldt-Jakob, multiple system atrophy and Fatal familial insomnia, are all caused by prions.
But in plants, these notorious molecules appear to play a more benign role. A protein called called luminidependens (LD) helps plants control their growth and flowering time by responding to changes in temperature and daylight. Now, research led by Susan Lindquist of the Whitehead Institute for Biomedical Research has uncovered evidence that LD acts like a prion. By inserting a snippet of the LD gene into yeast, Lindquist created a protein that misfolds, and spreads misfolding in a heritable manner.
Speaking with Nature News, Lindquist emphasised her results don't offer ironclad proof that LD is a prion. But if the hypothesis can be confirmed by follow-up studies, it points to a fascinating, memory-like mechanism in plants. Lindquist and her co-authors speculate that LD uses its shapeshifting abilities to create a physical trace of the outside environment, allowing cells to "remember" changes from previous seasons and years, and to put out leaves and flowers accordingly.
So, next time you're feeling frustrated that your daffodils popped up a few weeks early, bear in mind that everybody's memory plays tricks sometimes. In plants as in humans, we're still trying to figure out why.