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Research Reveals Corn Plants’ Evolving Water-Detection Abilities

A recent study led by researchers at Stanford University indicates that certain corn varieties, particularly those bred for high yield in the United States, may have diminished capabilities in locating water in soil. This insight is especially critical as climate change is exacerbating drought conditions, suggesting that there is an urgent need to develop corn strains that can better withstand these challenges.

The findings, published in the journal Science, provide a deeper understanding of the genetic controls involved in “hydropatterning”—the process by which corn roots adjust their growth toward water sources while steering clear of arid patches in the soil. The team highlighted the role of ethylene, a gaseous plant hormone typically associated with ripening in fruits like bananas, as a key factor influencing root behavior.

According to José Dinneny, senior author of the study and a professor of biology at Stanford, “Plants have an intricate method for detecting moisture in the soil. The genes tied to this ability are crucial for forming a root system that efficiently captures water.” Dinneny explained how corn roots utilize ethylene, which is generated by the roots themselves, to perceive air spaces in the soil, leading to regulated branching decisions.

Understanding Water-Responsive Root Systems

The Dinneny lab’s previous research showcased corn roots’ acute sensitivity to moisture, but the current study underscores that the effectiveness of this sensitivity varies significantly among different corn varieties. Researchers established a novel approach to study root water sensitivity, allowing them to evaluate 250 corn varieties that represent the genetic diversity seen in contemporary corn breeding practices.

The results revealed that corn varieties originating from tropical or subtropical regions, like Mexico, excelled in branching toward moist areas while evading drought-stricken zones. In contrast, varieties adapted to temperate climates in North America often developed roots in arbitrary directions, failing to differentiate between wet and dry sections of the soil. This research benefited from an international collaboration involving experts in quantitative genetics, evolution, and root development.

The team also suggested that modern agricultural practices in the U.S. may have inadvertently compromised the plants’ ability to seek moisture through their roots. Observations from field studies indicated that enhanced hydropatterning correlates with increased root depth.

Lead author Johannes Scharwies noted, “Plants that effectively locate water tend to develop deeper root systems. A possible explanation is that by avoiding unproductive areas, the plant can redirect energy toward deeper growth, where moisture is more abundant.”

Improving Drought Resistance in Corn

Investigations into the genetic makeup of these corn varieties disclosed that two plant hormones—auxin and ethylene—are influential in how roots respond to water availability. While auxin was previously recognized as a critical player in this process, the study’s insights into ethylene’s role were novel. The researchers conducted experiments with thale cress (Arabidopsis thaliana), finding that the signaling pathways of both hormones work in tandem: auxin promotes root branching towards moisture, whereas ethylene constrains it in oxygen-rich conditions.

While the researchers acknowledge the necessity for further inquiry to fully unravel these genetic interactions, their study emphasizes the significance of localized root responses. “Every root tip functions akin to a sensor, actively searching for water and nutrients and determining the direction for new root branches,” stated Scharwies. “To foster more drought-resistant corn varieties, we need to concentrate on these localized responses to comprehensively understand plant behavior.”

The study included contributions from other Stanford researchers, such as technician Taylor Clarke and lab manager Andrea Dinneny, along with collaborators from esteemed institutions like the Howard Hughes Medical Institute and Iowa State University, among others. Additionally, funding for this research was provided by several organizations, including the U.S. Department of Energy and the European Research Council.

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