An international team of researchers led by The Pennsylvania State University (Penn State) have found a gene that regulates the angle of root growth in corn, a discovery that will enable the breeding of deeper-rooting crops with enhanced ability to take up nitrogen.

The gene, called ZmCIPK15, was found to be missing in a naturally occurring mutant corn line that grows roots at steeper angles that make them go deeper into the soil. They identified the gene using a genome-wide association study, which involves statistical analysis of a genome-wide set of genetic variants in different plant lines to see what genes are associated with a trait.

The Penn State team screened nearly 500 lines of corn over four years in South Africa. Roots of selected plants were excavated and measured, validating the functional importance of the ZmCIPK15 gene. The researcher found that it caused an approximate 10-degree change in root angle. The steeper root growth angle markedly improved nitrogen capture. Infield studies under suboptimal nitrogen availability, the cipk15 mutant with steeper growth angles had 18% greater shoot biomass and 29% greater shoot nitrogen accumulation compared to the wild type, after 70 days of growth.
(Source: Crop Biotech Update, International Service for Acquisition of Agri-Biotech Applications.

These images of root architecture in the field show the cipk15 mutant corn genotype had significantly steeper angles compared to the wildtype genotype. Plants were grown in low nitrogen conditions. The mutant corn line that produced the root on the right lacks a gene that regulates root growth. Photo Credit: Hannah Schneider/Penn State