Plants “remember” drought, adapt
Research carried out at the University of Nebraska-Lincoln (UNL; USA) shows that plants subjected to a previous period of drought learn to deal with the stress owing to their “memories” of the experience. The research also confirms for the first time the scientific basis for what home gardeners and nursery professionals have often observed: Transplants do better when water is withheld for a few days to drought-harden them before the move.
According to Michael Fromm, a plant scientist with UNL and one of the co-authors of the research, “This phenomenon of drought hardening is in the common literature but not really in the academic literature. The mechanisms involved in this process seem to be what we found” (newsroom.unl.edu/blog/?p=1034).
Working with Arabidopsis, a member of the mustard family, Fromm, plant molecular biologist Zoya Avramova, and post-doctoral fellow Yong Ding compared the reaction of plants that had been previously stressed by withholding water to those not previously stressed (see “Multiple exposures to drought ‘train’ transcriptional responses in Arabidopsis,” Nature Communications, doi:10.1038/ncomms1732, 2012).
The prestressed plants bounced back more quickly the next time they were dehydrated. That is, the nontrained plants wilted faster than trained plants, and their leaves lost water at a faster rate than trained plants. Fromm said, “The plants ‘remember’ dehydration stress. It will condition them to survive future drought stress and transplanting.”
The team found that the trained plants responded to subsequent dehydration by increasing transcription of a certain subset of genes. During recovery periods when water is available, transcription of these genes returns to normal levels, but following subsequent drought periods the plants remember their transcriptional stress response and induce these genes to higher levels in this subsequent drought stress.”
Arabidopsis forgets this previous stress after five days of watering, although other plants may differ in that memory time. This is the first instance of transcriptional memory found in any life form above yeasts.
This discovery may lead to breeding or engineering of crops that would better withstand drought, although practical applications of these findings in agriculture are years away, Fromm said.
Home gardeners, though, can make immediate use of these findings. “If I was transplanting something, I would deprive it of water for a couple of days, then water overnight, then transplant,” Fromm said.