Penn State researcher Sally Mackenzie didn’t really set out to scare soybeans. But that’s what she did when she silenced the plants’ MSH1 gene. Though the plants were growing in perfect conditions, they suddenly sensed they were encountering a wide range of stresses all at once – drought, extreme cold and heat, high light levels and more. Plants reacted by amplifying gene responses to deal with the stresses. Then, when Mackenzie crossbred those plants with the original stock, the progeny “remembered” the stress of the parent plants and grew up more vigorous, resilient and productive. The discovery has important implications for breeding plants prepared for climate extremes.
A Decade in the Making
It took Mackenzie discovered the MSH1 gene about a decade ago. It’s something that all plants have, but at the time, she didn’t realize it’s importance.
“Recently, by serendipity, we discovered that after we replace the MSH1 gene, the plant has a ‘memory’ of that stress — and by memory I mean its growth features are very different from the plant we started with,” she said. “And it will remember the stress generation after generation after generation, as long as we don’t make any crosses and keep it in the same lineage.”
Plants that “detect” stress after the MSH1 gene is silenced can adjust their growth and change root configuration, limit above-ground biomass, delay flowering time and alter their response to environmental stimuli. Those responses are “remembered,” researchers report, and are passed in selective breeding through many generations.
As part of their recent research, plants derived from crosses with the “memory” soy bean plants were grown at large scale in four different field conditions at four widely separated locations in Nebraska. They were more vigorous, higher-yielding and better adapted to their environment than typical soybean plants.
“What it means,” says Mackenzie, “is that we can take our very best crop varieties and possibly get more out of them and make them more resilient with a fairly straightforward manipulation,” she said. “We saw a significant enhancement in yield and growth performance, which is unexpected because we didn’t introduce any new genes. We just changed the way they are expressed. And all of a sudden, we had a 13-14 percent increase in the yield of soybeans.”
Mackenzie suggests that all plants have this capacity, and that “the condition we describe is likely to be an important part of how plants transmit memory of their environment to precondition progeny.” Her team chose to work with soybeans because it is the most widely grown legume in the world, and second only to grasses in economic importance. But they have begun to work with other plants as well.
Why do we care?
This work has significant implications for plant breeding. Unlike Genetically Modified Organisms, new genetic material is not inserted into the plant. Rather, this technique is “epigenetic” involving the expression of existing genes.
It also has significant implications for our ability to grow food in climates that may become harsher in the future. We may be able to breed more heat and drought tolerant grasses, grains and legumes. In fact, Mackenzie has been pursuing this line of research in an effort to improve food security across the planet.
In places like Syria and Lebanon that have been hit so hard by climate change and war that they cannot produce their own food, this will be especially important, she noted.
“If you start adding up countries that really are not food secure, it is scary,” Mackenzie said. “Because if they can’t feed their own people, who is going to do it? It is not reasonable to think that we can increase our food production on this continent to manage all of that. One way or another, we have to find ways to produce food in those recalcitrant, difficult environments.”
Stay tuned! I’ll be looking for examples of this technique being used to the benefit of graziers in the future.