By Andi Anderson
A new University of Michigan study has revealed how nutrient-rich soil can influence the evolution of plant defenses. Led by U-M scientist Mia Howard, the research focused on goldenrod plants and how they adapt to protect themselves from insects.
The study, published in the journal Oikos, showed that goldenrods growing in fields treated with agricultural levels of nitrogen were more likely to develop a defense called "nodding." This trait causes the plants to bend their stems, making it harder for insects to lay eggs in the stem tips.
Goldenrod, a common North American plant, often falls victim to insects that inject eggs into its stems. These eggs form galls, which become protective homes for larvae. However, goldenrods with the nodding trait can avoid this problem by bending their stems when insects are most active.
Howard conducted her research at Michigan State University’s W.K. Kellogg Biological Station. The site has long-term experimental plots treated with nitrogen fertilizer. Howard compared goldenrod plants in fertilized plots to those in nearby unfertilized plots. She found a higher number of nodding goldenrods in the fertilized fields.
Nodding is a genetic trait, meaning only goldenrod plants with this ability will display it, regardless of the soil’s nitrogen levels. This made it easy for researchers to identify and track nodding plants during their field surveys.
Howard emphasized the value of long-term experiments in understanding plant evolution. Thanks to the decades-long study at Kellogg, researchers could observe meaningful changes in goldenrod populations over time.
The research highlights how environmental factors like soil nutrients can shape plant defenses. Howard called it an exciting example of plant evolution happening in real time, showcasing the importance of continued scientific observation.
This study also shows how natural defenses in plants might become stronger when resources in the environment change, especially with increased nutrient availability.
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Categories: Michigan, Education