UNIVERSITY PARK — By manipulating the expression of one gene, geneticists can induce a form of “stress memory” in plants that is inherited by some progeny, giving them the potential for more vigorous, hardy and productive growth, according to Penn State researchers, who suggest the discovery has significant implications for plant breeding.
And because the technique is epigenetic — involving the expression of existing genes and not the introduction of new genetic material from another plant — crops bred using this technology could sidestep controversy associated with genetically modified organisms and food.
“One gene, MSH1, gives us access to what is controlling a broad array of plant resiliency networks,” said Sally Mackenzie, professor of plant science in the College of Agricultural Sciences and professor of biology in the Eberly College of Science. “When a plant experiences a stress such as drought or prolonged extreme heat, it has the ability to adjust quickly to its environment to become phenotypically ‘plastic’ — or flexible.”
There are many ways to inactivate the MSH1 gene, researchers explain, and in this context they all work. In well-studied plant species, such as Arabidopsis, tomato or rice, it is possible to identify mutations in the gene. In others, and for commercial testing, it is possible to design a transgene that uses “RNA interference” to specifically target MSH1 for gene silencing. Any method that silences MSH1 results in very similar outcomes, they report.
“When plants are modified epigenetically, they can modify many genes in as simple a manner as possible,” Mackenzie pointed out. That includes adjusting the circadian clock — detecting light and triggering growth and reproductive phases — and modifying hormone responses to give them maximum flexibility, making them more resilient.
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 reported, and passed in selective breeding through many generations.
The researchers identify pathways that enhance root growth and plant vigor — increasing yield. They present their results on May 5 in Nature Communications. When an MSH1-modified plant is crossed or grafted, this enhanced plant vigor becomes quite pronounced.
Researchers contend that plants can be “reprogrammed” epigenetically to express genes differently without altering genotype, which constitutes a non-traditional approach to breeding.
