Researchers offer hope for adapting crops to climate change

Source: Tiffany Stecker, E&E reporter • Posted: Friday, March 8, 2013

What if plants could switch their genes on and off, depending on which traits were important in a certain climate?

That’s what a team of researchers at the Salk Institute for Biological Studies investigated in a series of studies on Arabidopsis thaliana, a common mustard weed across the Northern Hemisphere. Their work has led to a deeper understanding of a hidden layer of genetic diversity that could bring further advances in plant breeding and bioengineering.

The potential of switching genes on and off falls under the relatively new field of epigenetics (the prefix “epi” means “on top of” in Greek). It is the study of a pattern of chemical markers that regulate genes that sit over the DNA sequence. Genetic mutations are caused by changes in the pattern of nucleotide bases — the building blocks of DNA. Epigenomic modifications do not affect these building blocks and therefore don’t leave a permanent change in DNA

Epigenetic modifications are, in theory, reversible. This means plants could temporarily activate or deactivate genes, said Joseph Ecker, a plant biologist at the Salk Institute and co-author of the compiled findings, published in the journal Nature yesterday.

“It might be reversed in response to stress or a change in the environment,” he said. For example, a plant might adapt to need less water during a drought period or to flower at higher temperatures than its plant ancestors did. Epigenetics also has applications in human genetics and could help scientists gain valuable insight into the study of cancer.

Genetic adaptation occurs through evolution — which can take hundreds of years. Adaptation through epigenetics might happen much faster, said Ecker. For the mustard weed A. thaliana, a plant that can reproduce a new generation every eight weeks, Ecker and his colleagues have observed what looked like epigenetic modifications after 30 generations, or about five years.

Creating genetic diversity in the lab

Epigenetics could also help promote diversity in species that have been steadily losing it. In the domestication process for agriculture, humans domesticated a rather small portion of wild plants to bring out certain traits, like high-yielding plants or tasty fruit.

This was a genetic bottleneck and led to limited diversity. Breedings techniques over the last several centuries have led to the loss of genes that could be helpful to plant geneticists looking for drought-tolerant, heat-withstanding varieties that could be valuable for agricultural climate change adaptation.

Two large agricultural organizations recently invested $109 million for seed banks, which collect and save seeds that could store important genetic traits (ClimateWire, Feb. 6).

Epigenetic research could save scientists from going into the wild to collect seeds to reclaim lost genetic material, said Ecker. Two groups, one in Switzerland and one in France, are creating epigenetic variation to replace genetic diversity in the lab.

“Using epimutations, they found the range of phenotypes can be great,” Ecker said. Phenotype is the physical manifestation of a gene. “There is potential for creating new diversity, epigenetic diversity.”

The research is still preliminary, said Ecker. The time period for many experiments hasn’t been long enough to observe the stability of epigenes. The study of epigenetics has only taken hold in the last decade, he added, and skeptics of the science do exist. It has yet to be proven as a useful approach to plant breeding, said Ecker.

“The bottom line is, we don’t fully understand the mechanisms,” he said.