Genome-Wide Association Study of Metabolic Traits in the Duckweed Spirodela polyrhiza

The exceptionally high growth rate and high contents of flavonoids make the giant duckweed Spirodela polyrhiza (L.) Schleid. (Arales: Lemnaceae) an ideal organism for food production and metabolic engineering. To facilitate this, identification of the genetic basis underlying growth and metabolic traits is essential. Here, we characterized the genetics underpinning the growth and contents of 42 metabolites in S. polyrhiza using a genome-wide association (GWA) approach. We found that biomass positively correlates with contents of many free amino acids, including L-Glutamine, L-Tryptophane and L-Serine, but negatively correlates with many specialized metabolites, such as flavonoids. GWA analysis showed that several candidate genes were simultaneously associated with several metabolic traits, qualifying them as targets for growth manipulation and metabolic engineering. Together, this study provides insights into the metabolic diversity of S. polyrhiza and its underlying genetic architecture, paving the way for industrial applications of this plant via targeted breeding or genetic engineering.