Roger Deal is trying to figure out how plants remember drought.
An assistant professor of biochemistry and genetics at Emory University, Deal says most plants have a kind of memory for stress. When experiencing water shortage, for example, plants close the holes in their leaves, called stomata, to reduce water loss from their tissues. This, in turn, slows photosynthesis and plant growth. If the plants recover and go through a similar situation again, their cells somehow recall what that stress was like, so they’re able to bounce back more rapidly.
Deal is focusing his attention on a close relative of alfalfa, Medicago truncatula, which seems to have a better memory than most. For some reason, Medicago is able to turn off its stress response much faster after drought eases — in a matter of hours versus days. As a result, it can recover more quickly and begin growing again as soon as better conditions arrive.