Comparative evolutionary genetics of deleterious load in sorghum and maize

Authors: LOZANO, ROBERTO - Cornell University; GAZAVE, ELODIE - Cornell University; DOS SANTOS, JHONATHAN P.R. - Universidad De Sao Paulo; VALLURU, RAVI - Cornell University; BANDILLO, NONOY - Cornell University; FERNANDES, SAMUEL - University Of Illinois; BROWN, PATRICK - University Of California, Davis; SHAKOOR, NADIA - Danforth Plant Science Center; MOCKLER, TODD - Danforth Plant Science Center; ROSS-IBARRA, JEFFREY - University Of California, Davis; Buckler, Edward - Ed; GORE, MICHAEL - Cornell University

Submitted to: Nature Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2020
Publication Date: 1/15/2021
Citation: Lozano, R., Gazave, E., Dos Santos, J., Valluru, R., Bandillo, N., Fernandes, S., Brown, P.J., Shakoor, N., Mockler, T., Ross-Ibarra, J., Buckler IV, E.S., Gore, M.A. 2021. Comparative evolutionary genetics of deleterious load in sorghum and maize. Nature Plants. (7):17-24. https://doi.org/10.1038/s41477-020-00834-5.
DOI: https://doi.org/10.1038/s41477-020-00834-5

Interpretive Summary: Sorghum and maize share a similar evolutionary development and comparing their genomic variation reveals the genetic commonalities and differences between each species. This study specifically compared the deleterious mutations (mutations in the gene sequence that threaten the health of the species) in both corn and maize. One conclusion of this study is that unlike maize, sorghum has not experienced higher deleterious mutations as a result of domesticating formerly wild varieties. This study was also able to estimate with some accuracy the impact of genetic mutations in both species genes. This information will be useful for future breeding efforts in sorghum and maize.

Technical Abstract: Sorghum and maize share a close evolutionary history that can be explored through comparative genomics. To perform a large-scale comparison of the genomic variation between these two species, we analyzed 13M variants called from the whole genome resequencing (WGS) of 468 sorghum lines together with 25M variants previously identified in 1,218 maize lines. Deleterious mutations in both species were prevalent in pericentromeric regions, enriched in non-syntenic genes, and present at low allele frequencies. A comparison of deleterious burden between sorghum and maize revealed that sorghum, in contrast to maize, departed from the “domestication cost” hypothesis, which predicts a higher deleterious burden among improved compared to wild lines. Additionally, sorghum and maize population genetic summary statistics were used to predict a gene deleterious index with accuracies higher than 0.5. Our data refines previous estimates of deleterious mutations in sorghum, opening a venue to further characterize their impact on sorghum’s biology and breeding efforts.