The 2020 derecho revealed limited overlap between maize genes associated with root lodging and root system architecture

Roots anchor plants in soil, and the failure of anchorage (i.e., root lodging) is a major cause of crop yield loss. Anchorage is often assumed to be driven by root system architecture. We made use of a natural experiment to measure the overlap between the genetic regulation of root system architecture and anchorage. After one of the most devastating derechos ever recorded in August 2020, we phenotyped root lodging in a maize (Zea mays) diversity panel consisting of 369 genotypes grown in six environments affected by the derecho. Genome-wide association studies and transcriptome-wide association studies identified 118 candidate genes associated with root lodging. Thirty-four percent (40/118) of these were homologs of genes from Arabidopsis (Arabidopsis thaliana) that affect traits such as root morphology and lignin content, expected to affect root lodging. Finally, Gene Ontology enrichment analysis of the candidate genes and their predicted interaction partners at the transcriptional and translational levels revealed the complex regulatory networks of physiological and biochemical pathways underlying root lodging in maize. Limited overlap between genes associated with lodging resistance and root system architecture in this diversity panel suggests that anchorage depends in part on factors other than gross characteristics of root system architecture.