A graft between
two genotypes of Arabidopsis thaliana, shown in a confocal microscopy image.
One genotype has
plasma membranes marked in yellow, and the other marked in red. Researchers
studied the
movement of sRNAs across the graft junction, and the resulting epigenetic
changes in
the plants’
genome. Credit: Charles Melnyk at The Sainsbury Laboratory, Cambridge
University
(January 19, 2016) Salk
scientists find tiny molecules drive gene silencing across grafted shoots
Agricultural grafting dates back nearly 3,000 years. By
trial and error, people from ancient China to ancient Greece realized that
joining a cut branch from one plant onto the stalk of another could improve the
quality of crops.
Now, researchers at the Salk Institute and Cambridge
University have used this ancient practice, combined with modern genetic
research, to show that grafted plants can share epigenetic traits, according to
a new paper published the week of January 18, 2016 in the Proceedings of the
National Academy of Sciences.
“Grafting is something done often in the commercial world,
and yet, we really don’t completely understand the consequences for the two
plants,” says Joseph Ecker, one of the senior authors of the paper and director
of Salk’s Genomic Analysis Laboratory. “Our study showed genetic information is
actually flowing from one plant to the other. That’s the surprise to me.”
That genetic information shared between plants isn’t DNA—the
two grafted plants keep their original genomes—but epigenetic information is
being communicated within the plant.
In epigenetics, chemical markers act on existing genes in a
plant or animal’s DNA to turn genes on or off. Epigenetics can determine
whether a cell becomes muscle cell or a skin cell and determine how a plant
reacts to different soils, climates and disease.
“In the future, this research might allow growers to exploit
epigenetic information to improve crops and yields,” says Mathew Lewsey, one of
the first authors of the paper and a Salk research associate.