Study: Soybeans seem to inherit the bad memories of their parents
Research may lead to more resilient crops
University of Arkansas System Division of Agriculture
image:
A soybean looper (Chrysodeixis includens) caterpillar feeds on the leaf of a soybean plant as part of Arkansas Agricultural Experiment Station research on the impacts of drought-stress and herbivory.
view moreCredit: U of A System Division of Agriculture photo by Manish Gautam
By John Lovett
University of Arkansas System Division of Agriculture
Arkansas Agricultural Experiment Station
FAYETTEVILLE, Ark. — 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.
Pros and cons of stress memory
Kariyat and his doctoral candidates conducted multi-layered experiments to test if soybean plants under drought stress are more vulnerable to insects, and how much of the parental plant’s memory — its response to stress — is passed on to its progeny to cope with specific kinds of herbivory.
Progeny of stressed plants had seeds with higher nitrogen and protein content, key markers of plant fitness. Offspring also produced more flowers and had a greater density of trichomes, the tiny hair-like structures that defend against pests. Kariyat noted that these positive effects were strongest when parent plants experience both drought and herbivory pressure.
Despite these advantages, the stress memory came at a cost — strong defenses but weaker growth. Stressed progeny showed reduced yield, including a higher rate of empty pods.
Defensive trichomes also declined with maturity, suggesting that the enhanced defenses may be short-lived or age-dependent. The research suggests that there is a costly trade-off between survival and productivity, Kariyat said.
Kariyat concluded that their research so far points to stress memory in soybeans being a double-edged sword. While it can improve defense and early vigor, it also leads physiological trade-offs that ultimately reduce fitness and yield.
Experiment spotlight: Caterpillars on a bridge
To see whether insects could detect past drought stress in soybeans, the researchers built tiny bridges between previously drought-stressed plants and plants that had consistently received enough water. They observed soybean looper caterpillars pausing, rotating their heads and often reversing course back to the healthier plants, the study noted.
The scale of damage by the caterpillars on consistently watered plants was significantly higher than the plants that had recovered from drought stress, supporting the “plant vigor hypothesis” that pests prefer robust hosts.
First contact matters
Most previous studies focus on a single stressor, but real farm conditions often involve multiple. Kariyat’s team tested what happens when soybean looper and fall armyworm attack in sequence. What they found was surprising.
When soybean looper came first, soybean plant progeny had 40 percent higher nitrogen content, more flowers and pods, and better protein levels than when the order was reversed.
While this might suggest herbivory can prime soybeans for better performance, Kariyat cautions the effect depends on the type, timing and severity of stressors.
“It’s not that herbivory always improves the plant performance, but the type, severity and combination of stressors determine whether the responses would be beneficial or detrimental,” Kariyat said. “From the research so far, while moderate or minimum biotic stress may induce resilience in soybeans — and this is also found in other systems — the combined abiotic and biotic stress may lead to exhaustive performance, triggering expensive defensive responses that often compromise yield and fitness.”
For example, the hair-like structures on plants called trichomes increased in the progeny of plants that had been exposed to drought and herbivory treatments more so than those just for drought. However, when sequential herbivory was tested, there was no difference in trichome density, which suggested the plants were investing in physiology and fitness traits over physical defenses when coping with just herbivory.
This indicates that drought may play a major role in tipping the balance from beneficial stress to harmful overload.
Read the research
- “Drought and Herbivory Have Selective Transgenerational Effects on Soybean Eco-Physiology, Defence and Fitness,” was published in July in Plant, Cell & Environment by Gautam and Kariyat.
- “Transgenerational Imprints of Sequential Herbivory on Soybean Physiology and Fitness Traits,” by Shafi and Kariyat, was published in Plant-Environment Interactions in June.
- “Drought and Herbivory Drive Physiological and Phytohormonal Changes in Soybean (Glycine max Merril): Insights From a Meta-Analysis,” was published in Plant, Cell & Environment by Gautam and Kariyat in April.
- An earlier study by Gautam, Kariyat and Shafi on drought and herbivory in soybean was published in August 2024 by Environmental and Experimental Botany under the title “Compensation of physiological traits under simulated drought and herbivory has functional consequences for fitness in soybean (Glycine max (L.) Merrill).”
Shafi is co-advised by Ioannis Tzanetakis, professor of plant virology for the experiment station and director of the Arkansas Clean Plant Center.
To learn more about the Division of Agriculture research, visit the Arkansas Agricultural Experiment Station website. Follow us on X at @ArkAgResearch, subscribe to the Food, Farms and Forests podcast and sign up for our monthly newsletter, the Arkansas Agricultural Research Report. To learn more about the Division of Agriculture, visit uada.edu. Follow us on X at @AgInArk. To learn about extension programs in Arkansas, contact your local Cooperative Extension Service agent or visit uaex.uada.edu.
About the Division of Agriculture
The University of Arkansas System Division of Agriculture’s mission is to strengthen agriculture, communities, and families by connecting trusted research to the adoption of best practices. Through the Agricultural Experiment Station and the Cooperative Extension Service, the Division of Agriculture conducts research and extension work within the nation’s historic land grant education system.
The Division of Agriculture is one of 20 entities within the University of Arkansas System. It has offices in all 75 counties in Arkansas and faculty on three system campuses.
Pursuant to 7 CFR § 15.3, the University of Arkansas System Division of Agriculture offers all its Extension and Research programs and services (including employment) without regard to race, color, sex, national origin, religion, age, disability, marital or veteran status, genetic information, sexual preference, pregnancy or any other legally protected status, and is an equal opportunity institution.
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Journal
Plant-Environment Interactions
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Transgenerational Imprints of Sequential Herbivory on Soybean Physiology and Fitness Traits
Scientists get back to basics with minimal plant genomes
Salk Institute
image:
Todd Michael
view moreCredit: Salk Institute
Background: Ancient events in plant evolution have left behind large, duplicated regions in their genomes.
New discovery: Salk Institute scientists found that deleting these large blocks of DNA can still lead to normal plants.
The findings demonstrate that large chromosomal deletions are a viable strategy in plant genetic engineering, which could now accelerate the development of streamlined, minimal plant genomes—a major goal in industries looking to create new plant-based biotechnologies.
The new study, led by Salk Research Professor Todd Michael and computational scientist Ashot Papikian, was published in Proceedings of the National Academy of Sciences on August 11, 2025.
More details: The researchers used CRISPR-Cas9 to delete four large, duplicated blocks in Arabidopsis thaliana, a model plant commonly used in plant biology research. The deletions were then verified using whole-genome sequencing, which revealed minimal off-target effects.
While two deletion lines showed distinct phenotypes resulting from the loss of many genes, two others displayed no obvious defects. RNA-sequencing revealed that expression compensation, where deletions of duplicated genes led to the upregulation of intact duplicates, was not a general response to the deleted regions under these conditions.
The results suggest that it is possible to obtain viable plants when deleting large fragments that may be redundant or that contain non-essential genes.
Why this is important: These findings challenge the assumption that these duplicated regions are essential and highlight the potential redundancy or modularity within plant genomes. The scientists’ approach of removing entire duplicated blocks now offers a powerful strategy to functionally dissect conserved genomic regions, investigate gene linkage and dosage effects, and accelerate the development of streamlined, minimal plant genomes with broad implications for plant biology, synthetic genomics, and biotechnology.
Other authors include: Rachel J. Rattner, Jenni Kao, Neil Hauser, Nicholas Allsing, Allen Mamerto, Nolan T. Hartwick, and Kelly Colt at Salk.
Funding: This work was supported by the Harnessing Plants Initiative at the Salk Institute, with funding from TED Audacious and the Bezos Earth Fund.
About the Salk Institute for Biological Studies:
Unlocking the secrets of life itself is the driving force behind the Salk Institute. Our team of world-class, award-winning scientists pushes the boundaries of knowledge in areas such as neuroscience, cancer research, aging, immunobiology, plant biology, computational biology, and more. Founded by Jonas Salk, developer of the first safe and effective polio vaccine, the Institute is an independent, nonprofit research organization and architectural landmark: small by choice, intimate by nature, and fearless in the face of any challenge. Learn more at www.salk.edu.
Journal
Proceedings of the National Academy of Sciences
Method of Research
Experimental study
Article Title
Targeted deletions of large syntenic regions in Arabidopsis thaliana
Article Publication Date
11-Aug-2025
