The stability of fatty acid composition in sunflower oil is dependent on environment and affected by structural variation

Authors: INGOLD, MARKUS - Johannes Gutenberg University; GAO, QINGMING - Cibus; REINERT, STEPHAN - Friedrich-Alexander University; MANDEL, JENNIFER - University Of Memphis; BARB, JESSICA - University Of Georgia; RIESENBERG, LOREN - University Of Colorado; BURKE, JOHN - University Of Georgia; Hulke, Brent

Submitted to: bioRxiv
Publication Type: Pre-print Publication
Publication Acceptance Date: 5/7/2026
Publication Date: 5/7/2026
Citation: Ingold, M., Gao, Q., Reinert, S., Mandel, J.R., Barb, J., Riesenberg, L.H., Burke, J.M., Hulke, B.S. 2026. The stability of fatty acid composition in sunflower oil is dependent on environment and affected by structural variation. bioRxiv. https://doi.org/10.64898/2026.05.04.722759.
DOI: https://doi.org/10.64898/2026.05.04.722759

Interpretive Summary: In sunflower and all oilseeds, fatty acid composition is an important factor of marketability of the oil product. For sunflower, specifically, there is an emphasis on maximizing the amount of the omega-9 oleic acid, because it is oxidatively stable in storage and high temperature and has characteristics favorable for heart health. However, the high oleic sunflower trait expresses differently across environments. We determined the genes responsible for this difference in fatty acid composition across environments. Genes that result in high oleic acid minimally account for differences across environments. This finding will allow us to breed sunflower with high oleic acid in the seed oil with reduced differences based on environment in which the crop is grown.

Technical Abstract: In sunflower (Helianthus annuus L.), the composition of fatty acids in the seeds, primarily oleic, linoleic, stearic and palmitic acid, are of utmost importance for oil quality. In spite of this, the genetic basis of this trait and its interaction with the environment is poorly understood. Understanding this interaction is critical to improvement of sunflower. In this work, we incorporated fatty acid composition measurements from the sunflower SAM population and eight environments across a geographic cline into GWAS. The SAM panel consists of 287 varieties representing approximately 90% of sunflower diversity and for which 2.2 million high quality SNPs with a MAF > 5% are available. For increased power, multivariate GWAS incorporating the four fatty acids were used. Multivariate GWAS was performed with four different inputs: (i) mean fatty acid composition within each environment without omitting high oleic varieties, (ii) mean fatty acid composition within each environment omitting high oleic varieties, (iii) trait stability within environments quantified by standard errors within replicates (a stability) and (iv) Eberhart and Russell’s ß which quantifies trait stabilities across environments (ß stability). All four analyses yielded highly significantly associated SNPs. We found that high oleic varieties also coincided with high beta trait stability, resulting in markers between analysis (i) and (iv) largely overlapping, with signals being fairly consistent between environments in analysis (i). For analysis (ii) and (iii), significantly correlated markers tended to vary between trials. For all significant SNPs across analyses, 147 candidate genes were identified, including promising candidates such as 15 fatty acid metabolism genes, 6 heat shock proteins and 22 transcription factors. Lastly, a large introgression on Chromosome 5 was found to coincide with standard errors in the Georgia trial, suggesting a role in seed homogeneity in relation to FA composition under high heat conditions.