Molecular analysis of double mutants for flower fragrance and coloration in fragrant cyclamen

Flower fragrance and coloration are important traits in flowering plants. We previously produced the white-flowered fragrant cyclamen mutant ‘Kinu-no-mai’ (KN) from the purple-flowered cultivar ‘Kokou-no-kaori’ (KO) by ion-beam irradiation. HPLC analysis showed that malvidin 3,5-diglucoside is the main component of flower coloration in KO, while, in contrast, no anthocyanins were found in the petals of KN. In addition, we analyzed and compared the aroma components of KO and KN using GC/MS. Cinnamaldehyde, hydro-cinnamic alcohol and cinnamyl alcohol, which are aromatic compounds, were detected only in KO, while no significant differences were found for other monoterpenes and sesquiterpenes. From these results, we conclude that a double mutation affecting anthocyanin and aroma component biosynthesis pathways have occurred in KN. To determine the mutated factors, we tried RNA-seq analysis and compared the expression of several genes that might be involved in flower coloration and fragrance between KO and KN. Expression of a new glutathione S-transferase (CkoGST) that has not been reported previously, was significantly lower in the petals of KN compared to KO. Moreover, in KN, some genes related to cinnamyl alcohol biosynthesis showed lower expression compared with KO. Our study contributes to the development of new cyclamen cultivars with excellent fragrance and new colors.