Integrated Metabolomics and Selection Signal Analysis Provide Insights Into the Selection for Flavonol Biosynthesis Associated With Lettuce Quality Improvement.

Lettuce is a critical leafy vegetable consumed worldwide and is a substantial dietary source of health-promoting compounds. Exploring changes in metabolism during lettuce domestication under artificial selection conditions is important to facilitate further breeding and cultivation for quality improvement. A liquid chromatography-mass spectrometry-based metabolomics approach was used to putatively identify 237 metabolites from 40 accessions, of which 130 were identified as metabolite identification level 1. Subsequently, 29 metabolites linked to lettuce quality improvement and their potential associated genes involved in lettuce domestication and differentiation were analysed. Muti-omics approach showed that metabolites involved in flavonol biosynthesis are the main metabolic distinctions between wild and modern cultivars, which is attributable to the selection signal observed in LsF3'H, a key enzyme involved in the catalysis of flavonoid hydroxylation at the 3'-position. These findings provide a comprehensive view of quality- and flavour-related metabolite variation in lettuce, reveal the potential for quality improvement associated with flavonol biosynthesis, and offer valuable insights into the genetic basis for improving lettuce flavour and nutrition.