Biosynthetic and Functional Color–Scent Associations in Flowers of Papaver nudicaule and Their Impact on Pollinators

Abstract

Despite increasing evidence for biosynthetic connections between flower pigments and volatile compounds, examples of such relationships in polymorphic plant species remains limited. Herein, color-scent associations in flowers from Papaver nudicaule (Papaveraceae) have been investigated. The spectral reflectance and scent composition of flowers of four color cultivars was determined. We found that pigments and volatiles occur in specific combinations in flowers of P. nudicaule. The presence of indole in the bouquets is strongly associated with the occurrence of yellow pigments called nudicaulins, for which indole is one of the final biosynthetic precursors. Whereas yellow flowers emit an excess of indole, orange flowers consume it during nudicaulin production and lack the substance in their bouquet. By using the honeybee, Apis mellifera, evaluations were made on how color and scent affect the discrimination of these flowers by pollinators. Honeybees were able to discriminate artificial odor mixtures resembling those of the natural flower odors. Bees trained with stimuli combining colors and odors showed an improved discrimination performance. The results indicate that the indole moiety of nudicaulins and emitted indole might be products of the same biochemical pathway. We propose that conserved pathways account for the evolution of color-scent associations in P. nudicaule and that these associations positively affect flower constancy of pollinators.

Formation of Nudicaulins In Vivo and In Vitro and the Biomimetic Synthesis and Bioactivity of O-Methylated Nudicaulin Derivatives

“…In orange petals, a mixture of red pelargonidin glucosides and yellow nudicaulins is responsible for the color. Under natural conditions, the low level of indole [11] probably confines the conversion of an excess of pelargonidin glucosides into nudicaulins. Therefore, drops of an aqueous indole solution were applied to the surface of orange petals.…”

Coordination among flower pigments, scents and pollinators in ornamental plants

“…Research indicates that the combination of floral scent and color provides more reliable rewards for foraging bees, ultimately increasing flower reproductive success. In Papaver nudicaule, the combination of scent and color cues significantly enhances the discrimination of honeybees, suggesting the positive influence of color-scent associations on pollinator constancy (Martínez-Harms et al 2018). Moreover, bumblebees demonstrate improved discrimination abilities when the scent pattern corresponds to a matching visual color pattern.…”

Chemistry, biosynthesis and biology of floral volatiles: roles in pollination and other functions

“…96 Intriguing reports describe an amino acid-derived oral volatile that also has a role in the biosynthesis of a oral pigment. The volatile indole (94), derived from the tryptophan biosynthetic pathway, is released directly from the owers of certain poppy species, 100 and also appears to combine with avonoids to form the unique pigments called nudicaulins 101 via reactions that still need investigation.…”