By John Lovett
When soybean plants survive attacks from insects and periods of drought, they remember.
While plants don’t remember in the way animals do, research out of the Arkansas Agricultural Experiment Station shows that soybean plants can pass on adaptive responses to stress like those hungry insects across generations without changing their DNA.
Scientists call this kind of adaptation across generations “transgenerational plasticity,” and the consensus has been the independent stressors of drought and herbivory, or animals feeding on plants, can induce gene expression possibly through epigenetics. Unlike genetic changes, or mutations, epigenetic changes are reversible and don’t change the DNA sequence, but rather how an organism read its DNA sequence.
Implications for agriculture
In soybean one of the world’s most important crops researchers with the experiment station, the research arm of the University of Arkansas System Division of Agriculture, have found the first evidence that drought and insect herbivory can create lasting, transgenerational effects. These stressors not only affect the parent plants but alter the traits and defenses of their offspring.
The research demonstrates some of the positive and negative impacts the stressors have on a plant’s progeny and could be used to develop more resilient crops in the same season.
As a vaccine can build immunity, techniques such as “priming” and “hardening” in the early vegetative stages might enable the plants to withstand future setbacks with minimum reduction in yield, according to Rupesh Kariyat, associate professor of crop entomology in the entomology and plant pathology department for the Division of Agriculture and the Dale Bumpers College of Agricultural, Food and Life Sciences.
“This gives us the opportunity where we can manipulate the degree of stress of soybean to bolster defenses early in the season without compromising the final yield of the crop,” Kariyat said. “But there is a catch we have yet to quantify the threshold under drought and herbivory stress that may cause more harm than good to the plants.”
For the past two years, Kariyat and doctoral students Manish Gautam and Insha Shafi have looked at how the caterpillars of two insects soybean looper and fall armyworm interact with soybean plants, and their effects on parent and progeny plants in a variety of situations including the coincidence of drought and sequential herbivory.
Ecology and economics
Kariyat, who holds the Clyde H. Sites Endowed Professorship in International Crop Physiology, notes that climate change is already making insect threats worse.
“Insects are getting bigger, and they’re going through multiple generations each year,” he said. “That leads to increased pesticide use, which isn’t sustainable.”
Improving soybean resilience through stress memory could reduce pesticide dependence, with significant ecological and economic benefits. While U.S. farmers typically purchase fresh seed annually, in Brazil and Kenya, many farmers rely on saved seeds to avoid the high cost of commercial varieties. In such systems, traits passed from parent plants to offspring become especially relevant.
Source : uada.edu