When a germinating seed is placed on its side, some roots bend earthward immediately, while others turn more slowly. Plant roots must be directed toward gravity for water and nutrients to be available. Understanding these directional mechanisms could help improve agriculture and ensure food security as global climate changes. A new study used machine vision to measure changes in growth direction in response to gravity (gravitropism) in thousands of corn seedling roots. It mapped the genomic regions in corn that influence the process.
When the researchers compared previous results from similar experiments on the distantly related Arabidopsis plant to their data from corn, they discovered four genes that control root gravitropism.
Gravitropism is an intriguing response to a change in the external circumstances of a plant. Many plant responses to environmental changes take days or weeks, but gravitropism can be seen in minutes to hours. For a long time, biologists have been fascinated by it. This study was intended to be the first step toward identifying genes that detect the direction of the gravity vector and adjust growth to follow it.
Knowing about gravitropism in detail may aid in modifying crop species to produce steeper roots, allowing them to access deeper water reserves. Shoots with steeper branch angles above ground may tolerate denser planting in fields.