Characterization of chloroplast iridescence in Selaginella erythropus

Abstract

Iridescence in shade-dwelling plants has previously been described in only a few plant groups, and even fewer where the structural colour is produced by intracellular structures. In contrast with other Selaginella species, this work reports the first example in the genus of structural colour originating from modified chloroplasts. Characterization of these structures determines that they form one-dimensional photonic multilayers. The Selaginella bizonoplasts present an analogous structure to recently reported Begonia iridoplasts; however, unlike Begonia species that produce iridoplasts, this Selaginella species was not previously described as iridescent. This therefore raises the possibility of widespread but unobserved and uncharacterized photonic structures in plants.

Gigantic chloroplasts, including bizonoplasts, are common in shade‐adapted species of the ancient vascular plant family Selaginellaceae

“…Recently, Masters et al. (, pp. 1, 6) successfully characterized iridescence in S. erythropus and determined that it is from “one‐dimensional photonic multilayers” (the upper zone of the Bp).…”

The Role of Periodic Structures in Light Harvesting

“…The results obtained corresponded to the color of the plant, thereby describing not only the color of leaves but also the iridescence visible on them [ 4 ]. Masters, in his work [ 5 ], investigated bizonoplasts in S. Erythropus. These bizonoplasts are a unique form of chloroplasts and, at the same time, a one-dimensional photonic crystal.…”

“…The formation of plant pigments, their effect on color, and efficiency of photosynthesis have been studied for a long period of time [ 1 , 2 , 3 ]. Nevertheless, the importance of structural coloration has only recently begun to be taken into consideration [ 4 , 5 , 6 , 7 , 8 ], thanks to new methods that use high resolution to examine the structure [ 4 ]. Structural coloration is thought of as resonant reflection or transmission that emerges due to the ordering of objects.…”

“…They also have an ability to control both the speed of optical radiation in such structures [ 13 ] and the localization of electromagnetic waves [ 14 ]. Examples of these structures, such as iridoplasts in begonia [ 4 ], chloroplasts of Selaginella erythropus [ 5 ], bisonoplasts [ 15 ], giant chloroplasts [ 16 ], lamelloplasts [ 17 ], algae [ 18 ], epicuticular wax [ 6 ], and others [ 19 ], have been described in a number of studies.…”

Light-Dependent Morphological Changes Can Tune Light Absorption in Iridescent Plant Chloroplasts: A Numerical Study Using Biologically Realistic Data

“…Their photonic properties were recently characterized for the first time (32). A schematic of their structure is represented in Figure 4 a and it behaves as a one-dimensional photonic crystal which reflects strongly in the blue, around 450 nm (21,22,32,33).…”