Links between vase-life, carotenoid composition, and retrograde signalling gene expression in lilies

Lilies (LA hybrid) flowers with white or yellow hues attain their colours due to a differential carotenoid composition. To explore how floral longevity might be related to the accumulation of carotenoid pigments, we assessed flower opening and senescence dynamics in cut stems of LA hybrid flowers. Among the four varieties tested, each evaluated through the analysis of over 150 flowers, yellow ‘Beau soleil’ had strongest evidence of chloroplast retention at anthesis and longer lifespan. In contrast, white ‘Litouwen’ developed more rapidly and lost photosynthetic capacity faster. ‘Beau soleil’ and ‘Litouwen’ were selected to further understand biochemical and molecular strategies against oxidative stress and signalling. ‘Beau soleil’ had significantly higher lutein contents and increased xanthophyll thermal dissipation at initial flower opening, but it was α-tocopherol which correlated with the maximum quantum yield of PSII ( F v F m ) and lipid peroxidation products. A putative developmental specialisation in retrograde signalling was found with higher transient increased expression of an EXECUTER2 orthologue at anthesis. We conclude that carotenoid composition influences flower opening and longevity by retaining photosystem II activity and increasing photoprotective mechanisms. This study suggests new breeding targets for the cut flower industry showing the relevance of oxidative stress in variety selection that should be further validated in additional varieties of lilies as well as extended to other flowers with chloroplast degradation during flower opening.