Underground networks of roots forage for nutrients and water for plants sustenance. Yet, the genetic and molecular mechanisms that govern which parts of the soil roots explore remain largely unknown. In a breakthrough that will help reduce atmospheric carbon from plants, researchers from Salk Institute have discovered a gene that determines the depth of root growth in the soil. The findings of this study will allow researchers to develop plants that can help combat climate change as part of Salk's Harnessing Plants Initiative.

The researchers used thale cress (Arabidopsis thaliana) to identify genes that regulate the way auxin works. Auxin is a hormone which plays a key role in controlling the root system architecture of plants. The team found that the gene called EXOCYST70A3 directly regulates root system architecture by controlling the auxin pathway without disrupting other pathways. The gene does this by affecting the distribution of PIN4, a protein that influences auxin transport. When the researchers altered the EXOCYST70A3 gene, they found that the orientation of the root system shifted and more roots grew deeper into the soil.

In addition to developing plants that can grow deeper root systems that will store more carbon, this discovery could help scientists understand how plants address the seasonal variance in rainfall and how to help plants adapt to changing climates.

For more details, read the news article in Salk News.

Figure: Normal Arabidopsis thaliana plant with shallow root system architecture. Right: Arabidopsis thaliana mutant showing deeper root system architecture. (Roots are colored yellow in the image for better visibility.)

Credit: Salk Institute