What Keeps Plant Roots Growing Toward Gravity? Study Identifies Four Genes
Published:19 Oct.2022 Source:University of Illinois College of Agricultural, Consumer and Environmental Sciences
What happens belowground in a corn field is easy to overlook, but corn root architecture can play an important role in water and nutrient acquisition, affecting drought tolerance, water use efficiency, and sustainability. If breeders could encourage corn roots to grow down at a steeper angle, the crop could potentially access important resources deeper in the soil.
A first step toward that goal is learning the genes involved in gravitropism, root growth in response to gravity. In a new study published in the Proceedings of the National Academy of Sciences, University of Wisconsin scientists, in collaboration with researchers at the University of Illinois. identify four such genes in corn and the model plant Arabidopsis.
When a germinating seed is turned on its side, some roots make a sudden, steep turn towards gravity, while others turn a fraction more slowly. The researchers used machine vision methods to observe subtle differences in root gravitropism in thousands of seedlings and combined that data with genetic information for each seedling. The result mapped the likely positions of gravitropism genes in the genome.
The map got the researchers to the right neighborhood in the genome -- regions of a few hundred genes -- but they were still a long way from identifying specific genes for gravitropism. Fortunately, they had a tool that could help.
"Because we had previously performed the same experiment with the distantly related Arabidopsis plant, we were able to match genes within the relevant regions of the genome in both species. Follow-up tests verified the identity of four genes that modify root gravitropism. The new information could help us understand how gravity shapes root system architectures," says Edgar Spalding, professor in the Department of Botany at the University of Wisconsin and lead author of the study.