Genomic selection as an approach to select for reduced aflatoxin contamination in peanut under terminal drought stress

Authors: GIMODE, DAVIS - University Of Georgia; WALLACE, JASON - University Of Georgia; Holbrook, Carl - Corley; ISLEIB, THOMAS - North Carolina State University; CHU, YE - University Of Georgia; VIRK, SIMIR - University Of Georgia; PORTER, WES - University Of Georgia; OZIAS-AKINS, PEGGY - University Of Georgia

Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2024
Publication Date: 5/30/2024
Citation: Gimode, D., Wallace, J., Holbrook Jr, C.C., Isleib, T.G., Chu, Y., Virk, S., Porter, W., Ozias-Akins, P. 2024. Genomic selection as an approach to select for reduced aflatoxin contamination in peanut under terminal drought stress. Peanut Science. 51(1):18-31. https://doi.org/10.3146/0095-3679-51-PS23-4.
DOI: https://doi.org/10.3146/0095-3679-51-PS23-4

Interpretive Summary: Peanut is an important crop that is widely grown in all tropical and sub-tropical regions in the world. An important constraint to its production is contamination by aflatoxin. Pre-harvest aflatoxin contamination (PAC) occurs when the peanut is exposed to severe drought and heat stress prior to harvest. Development of genotypes that are either resistant or limiting to Aspergillus infection and/or that can curtail aflatoxin production is a key objective in peanut breeding. PAC is an extremely variable trait with a low heritability. Genomic selection is an approach that breeder might use to develop resistant genotypes. Unfortunately, this study did not show clear advantages of this method over conventional selection.

Technical Abstract: Pre-harvest aflatoxin contamination (PAC) occurs when the peanut is exposed to severe drought and heat stress prior to harvest. Development of genotypes that are either resistant or limiting to Aspergillus infection and/or that can curtail aflatoxin production is a key objective in peanut breeding. Using SNP markers and phenotype data on aflatoxin resistance collected in previous years, we utilized genomic selection (GS) to study PAC resistance in peanut. The technique was validated in the Florida-07 x GP-NC WS 16 recombinant inbreed population by assessing high heritability traits. GS was then deployed to study PAC resistance in the Tifrunner x C76-16 and Florida-07 x C76-16 populations. The resultant models yielded prediction accuracy values of 0.24 and 0.23 which while low, were comparable to the heritability values of 0.31 and 0.1 for each population, respectively. Using genomic estimated breeding values (GEBVs), entries were selected for two drought shelter studies. Manual scoring and multispectral imaging were used to acquire end season drought stress data. Low correlation values (-0.15 for shelter A and 0.32 for shelter B) were observed between the GEBVs and actual end season aflatoxin content. Correlations between visual drought ratings and PAC were also low (0.23 and 0.16 for shelter A and B, respectively). While strong inverse correlations were observed between GNDVI and visual drought ratings (-0.74 and -0.73 for shelter A and B, respectively). GNDVI did not confer a clear advantage for selection of PAC resistance. Ideally, the use of genome-spanning markers in GS may enable selection for a difficult to phenotype trait like PAC resistance. Although this study did not show clear advantages of the method over conventional selection, it is an important step for implementation of GS and use of GEBVs for trait selection in peanut.