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Laying Deeper Roots on Earth and Beyond

Researchers at Noble are gaining a better understanding of how deep and in what direction plant roots grow. Their hope is to provide knowledge that enables breeding of plants better able to utilize limited water and nutrient resources with the help of deeper roots.  

By Sabrina Chin, Postdoctoral Fellow

Posted Apr. 22, 2020

Oklahoma’s location between the humid eastern and semi-arid western zones of the USA make it vulnerable to drought. Furthermore, generations of farming in ways that don’t regenerate soil health have led to soils with poor nutrient and water retention. Researchers in Noble Research Institute’s Plant Cell Biology Laboratory are seeking ways to mitigate such problems by conducting basic research on roots. In doing so, they expect to contribute to pre-breeding efforts that will lead to new crop cultivars or novel chemical applications to make roots grow deeper and, thus, become more efficient in utilizing limited water and nutrient resources. In addition, their research has the potential to enhance not only farming and ranching on Earth, but also agriculture in space.

Roots and Gravity

The plant cell biology laboratory studies how roots grow down toward the soil by following gravity. This process is called gravitropism and is essential for roots to grow deeper into soil to reach soil zones with more moisture and nutrients.

Gravitropism was first studied by Charles Darwin as early as 1880. Despite centuries of study, plant scientists still do not completely understand how roots orchestrate this process. A recent research article published by the plant cell biology laboratory has added to this understanding.

Studying a Natural Plant Chemical Connected to Root Growth

In their new publication, researchers in the group, including current lab members Sabrina Chin, Alan Sparks and Elison Blancaflor, found that an internal plant chemical called brassinolide participates in telling the root to change its growth direction. In their experiments, they showed that roots of corn and legume seedlings treated with brassinolide had stronger gravitropism when compared with non-treated seedlings. Using a combination of high-powered microscopes and molecular tools to label living plant cells, the researchers found that brassinolide affected a component of the root cell called the cytoskeleton. The cytoskeleton, or cell skeleton, is also found in animal and human cells, such as muscle and nerve cells. Brassinolide caused the cytoskeleton to become less dense and organized.

Figure showing untreated roots and roots treated with brassinolide.Roots of corn seedlings respond to gravity more strongly when treated with a substance called brassinolide (top image). Green fibers show how the cytoskeleton in cells of a legume seedling look like under a microscope. Recent work from Noble Research Institute’s Plant Cell Biology Laboratory discovered that brassinolide instructs roots to grow down by regulating the cytoskeleton.

Could Brassinolide Help Roots Grow Deeper?

Although this research looks at what is going on at the cellular level, the results can potentially be applied to enhance crop production. For example, brassinolide and other chemicals that the laboratory are working on can be used as tools to investigate if seedling roots that redirect their growth toward gravity more quickly lead to deeper roots. Crops with deeper roots will likely improve crop productivity and yield as well as producer profitability by reducing irrigation dependency, soil erosion and fertilizer use.

Building Better Plants for Space

In addition to enhancing agriculture on Earth, this research is of interest to NASA, which partially funded this work. This is because the results can help guide the development of plants more suited to growth in space. With reduced gravity in space, roots have less control of their growth direction. A crucial question is whether reduced gravity will negatively affect the plants that are grown for food on future space missions. If so, can knowledge about brassinolides or the cytoskeleton be a target for designing plants with roots that are better adapted to life with minimal gravity? Thus, finding the root of root’s secrets is the key that will launch a thousand (space) ships!