Media Releases

New research shows forest trees remember their roots

July 12, 2011

TORONTO, ON — When it comes to how they respond to the envi­ron­ment, trees may not be that dif­fer­ent from humans.

Recent stud­ies showed that even genet­i­cal­ly iden­ti­cal human twins can have a dif­fer­ent chance of get­ting a dis­ease. This is because each twin has dis­tinct per­son­al expe­ri­ences through their life­time.

It turns out that the same is like­ly true for for­est trees as well, accord­ing to new research from the Uni­ver­si­ty of Toron­to Scar­bor­ough (UTSC).

“The find­ings were real­ly quite stun­ning,” says Mal­colm Camp­bell, a biol­o­gist and lead author of the study. “Peo­ple have been talk­ing about a so-called “nurs­ery effect” for a long time.”

The study looked at the the­o­ry that trees and oth­er plants, even when they were genet­i­cal­ly iden­ti­cal, grew dif­fer­ent­ly and respond­ed to stress dif­fer­ent­ly depend­ing on the nurs­ery that the plants were obtained from. Camp­bell says the research find­ings not only pro­vide a strong affir­ma­tion of this effect, but also reveal insight on a mol­e­c­u­lar lev­el. “Our results show that there is a form of mol­e­c­u­lar ‘mem­o­ry’ in trees where a tree’s pre­vi­ous per­son­al expe­ri­ence influ­ences how it responds to the envi­ron­ment.”

In the new study, Camp­bel­l’s grad­u­ate stu­dent Sherosha Raj used genet­i­cal­ly iden­ti­cal poplar trees that had been grown in two dif­fer­ent regions of Cana­da. These stem cut­tings were then used to regrow the trees under iden­ti­cal cli­mate-con­trolled con­di­tions in Toron­to. Raj sub­ject­ed half of the trees to drought con­di­tions while the remain­ing trees were well watered.

Since the trees were regrown under iden­ti­cal con­di­tions, Camp­bell and his research group pre­dict­ed all the spec­i­mens would respond to drought in the same man­ner, regard­less of where they had come from. Remark­ably, genet­i­cal­ly iden­ti­cal spec­i­mens of two poplar vari­eties respond­ed dif­fer­ent­ly to the drought treat­ment depend­ing on their place of ori­gin.

Camp­bel­l’s research group also showed that this dif­fer­ence occurred at the most fun­da­men­tal lev­el – the one of gene activ­i­ty. Even though the spec­i­mens were all genet­i­cal­ly iden­ti­cal, trees that had been obtained from Alber­ta used a dif­fer­ent set of genes to respond to drought than the ones that had been obtained from Saskatchewan.

The find­ings of this study are rel­e­vant to foresters and gar­den­ers in high­light­ing the impor­tance of the nurs­ery source for trees and oth­er plants, which can deter­mine how the plant will grow and resist stress in a for­est or the gar­den. Addi­tion­al­ly, the “mem­o­ry” of pre­vi­ous expe­ri­ence dis­cov­ered in this study could also help deter­mine plant sur­vival in response to changes in cli­mate, or oth­er envi­ron­men­tal stress­es like dis­eases or pests.

Dr. Camp­bel­l’s research team includ­ed co-first author Dr. Katha­ri­na Bräutigam, Erin Haman­ishi and Dr. Olivia Wilkins, all of the Uni­ver­si­ty of Toron­to. The work was done in col­lab­o­ra­tion with col­leagues at the Uni­ver­si­ty of British Colum­bia, Simon Fras­er Uni­ver­si­ty, and the Uni­ver­si­ty of Alber­ta.

The research was sup­port­ed by Nat­ur­al Sci­ences and Engi­neer­ing Research Coun­cil of Cana­da com­pet­i­tive research funds, and in kind con­tri­bu­tions from Alber­ta Pacif­ic For­est Indus­tries, and Agri­cul­ture and Agri­food Cana­da.

The study appears in this week’s issue of PNAS: The Pro­ceed­ings of the Nation­al Acad­e­my of Sci­ences.


For more infor­ma­tion, please con­tact:

Karen Ho
Media and Com­mu­ni­ca­tions Assis­tant
Uni­ver­si­ty of Toron­to Scar­bor­ough