Profiling Environmental Variations in Condensed Tannins and Other Metabolites of Birdsfoot Trefoil (Lotus corniculatus L.) Genotypes

<i>Lotus corniculatus</i> L., also known as birdsfoot trefoil (BFT), is a perennial, non-bloating, temperate forage legume widely grown due to its accumulation of high levels of condensed tannins (CTs) in foliage. However, variations in the CT levels and other plant metabolites in BFT genotypes in response to environmental and yearly factors under field conditions remain largely unexplored. Here, we combine conventional CT quantification and metabolome profiling with high-resolution liquid chromatography-mass spectrometry (LC-MS) to understand how environmental factors impact CT and other metabolite profiles. Eight BFT genotypes grown in Kentville, Canada, and Rhode Island and Utah in the United States were investigated, revealing significant genotypic variations in soluble CT contents. The global metabolome profiles of the eight BFT genotypes clustered predominantly based on geographical location. These results demonstrate that geographical location strongly influences CT accumulation and metabolome composition, offering potential for selecting genotypes adapted to specific environments. Our findings provide an opportunity for targeted breeding strategies to optimize CT levels, improve forage quality, and enhance stress resilience in birdsfoot trefoil.