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biophotonics
cell walls
fruit color
honest signaling
plant color
plant lipids
plant-animal interaction
seed dispersal
structural color
TEM tomography
anthocyanin
lipid
chemistry
color
fruit
genetics
lipid metabolism
metabolism
physiology
pigmentation
structure activity relation
Viburnum
Anthocyanins
Lipids
Structure-Activity Relationship
Abstract:
Middleton et al. report that the metallic blue appearance of Viburnum tinus fruits relies on a layered nanostructure of lipid globules in the epidermal cell wall. As this lipid-based structural coloration correlates with a high fat content, it is proposed that this represents an honest signal of nutritional value. © 2020 Elsevier Inc. Viburnum tinus is an evergreen shrub that is native to the Mediterranean region but cultivated widely in Europe and around the world. It produces ripe metallic blue fruits throughout winter [1]. Despite its limited fleshy pulp [2], its high lipid content [3] makes it a valuable resource to the small birds [4] that act as its seed-dispersers [5]. Here, we find that the metallic blue appearance of the fruits is produced by globular lipid inclusions arranged in a disordered multilayer structure. This structure is embedded in the cell walls of the epicarp and underlaid with a dark layer of anthocyanin pigments. The presence of such large, organized lipid aggregates in plant cell walls represents a new mechanism for structural coloration and may serve as an honest signal of nutritional content. © 2020 Elsevier Inc.
