Plants Do Math
In The Highest Frontier, Jenny and her classmates study Arabididopsis plants with a nervous system. Fanciful–but what if plants can already do math?
So what math problem do plants have to solve? How to survive the night without light for photosynthesis. That may not sound too hard–after all, we animals fast through the night until “break-fast.” But for many smaller animals, that’s not so easy. Some rodents have to eat their own weight’s worth of food in a day. And bats have to consume enough insects by night to survive through the next day.
What’s amazing about plants is that somehow they seem to “know” just how much energy to store from photosynthesis to get them through the night. That’s important because whatever energy they don’t have to store can be used to growth their leaves and outcompete their neighbors for space in the sun. Apparently, Arabidopsis plants have a circadian timer (a mechanism timed to measure the daylength) that allows just enough starch storage to get the plant through the night.
But how does this timer work? What is the molecular basis? Researchers hypothesize that the plant has a way to compute the ratio of the amount of starch left to the amount of time left till dawn. To test this hypothesis, they seek mutants that have predicted defects. For instance, one mutant retains too much starch by dawn, more than it should need. Another mutant was found to be unable to adjust its starch levels to a change in night length. We still don’t know what the mutant proteins do, and we’re probably a few mutants away from an answer. But if plant cells can conduct arithmetic division, that might suggest clues as to how our own brains do it–something we really don’t know either.