Deciphering the genetics of phyllodulcin biosynthesis and development of markers for breeding

The natural secondary metabolite phyllodulcin, a taste-active substance with a sweet profile in specific applications, is exclusively synthesized by individual varieties of Hydrangea macrophylla subspecies serrata , so-called tea-hortensias. To unravel the genetics of phyllodulcin biosynthesis, we crossed the tea-hortensias ‘Odoriko-Amacha’ and ‘Yae Amacha’ and developed an F 1 population comprising of 435 plants. The segregation of phyllodulcin, hydrangenol and thunberginol G contents at different harvest dates indicated a strong genetic control of these metabolite contents. Subsequent quantitative trait locus (QTL) analysis based on 282 randomly selected individuals of the first filial generation (F 1 ) detected 2–5 QTL per metabolite and parental map, which co-localized on chromosomes 6, 12, 15, 18 and two regions on chromosome 16. Alleles suppressing or promoting phyllodulcin, hydrangenol and/or thunberginol G biosynthesis were identified in both parental plants and a genotype-specific biosynthetic interaction among these metabolites was observed. Metabolite profiling of genotype-specific F 1 plant groups unraveled specific steps of phyllodulcin biosynthesis and a model was established including the phenyldihydroisocoumarins phyllodulcin, hydrangenol and the thunberginols C, D, E and G. • We unraveled the genetics and biosynthesis of the natural aromatic sweetener phyllodulcin. • The contents of phyllodulcin and its precursor metabolites, hydrangenol and thunberginol G, are genetically controlled. • Loci on chromosomes 6, 12, 15, 16, and 18 control phyllodulcin, hydrangenol and/or thunberginol G contents. • A biosynthetic model including phyllodulcin, hydrangenol and the thunberginols C, D, E and G was proposed.