Genetic loci and causal genes for seed fatty acids accumulation across multiple environments and genetic backgrounds in soybean

Soybean is a major oil crop in the world, and fatty acids are the predominant components for oil bio-synthesis and catabolism metabolisms and also are the most important energy resources for organisms. In view of this, two recombinant inbred line (RIL) populations (ZL-RIL and ZQ-RIL) and one natural population were evaluated for five individual seed fatty acid contents (palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid) under four different environments, simultaneously. In total, sixteen additive QTL clusters were identified in ZL-RIL population, and fifteen were stably expressed across multiple environments or had pleiotropic effects on various fatty acid contents. Furthermore, five and five of these 16 QTL clusters were verified in ZQ-RIL population and natural population, respectively. Among these consistent and stable QTL clusters, one QTL cluster controlling fatty acid on chromosome 5 with pleiotropic effect was identified under all of the environments in ZL-RIL and ZQ-RIL populations and also was validated in the natural population. Meanwhile, another stable QTL cluster was detected on chromosome 9 with pleiotropic effect under multiple environments in ZL-RIL population and was further verified by the natural population. More importantly, some causal genes, such as the genes on chromosome 9, involving in the fatty acid catabolism process were found in these stable QTL clusters, and some of them, such as Gm09G042000, Gm09G041500, and Gm09G047200 on chromosome 9, showed different expressions in ZL-RIL parents (Zheng92116 and Liaodou14) based on the transcriptome sequencing analysis at different seed developmental stages. Thus, the study results provided insights into the genetic basis and molecular markers for regulating seed fatty acid contents in soybean breeding program.