Light dependent morphological changes can tune light absorption in iridescent plant chloroplasts

Abstract

Chloroplasts, the organelles responsible for photosynthesis in most plants and algae, exhibit a variety of morphological adaption strategies to changing light environments which can have important yet overlooked light scattering effects. This can be even more significant for iridoplasts, specialized chloroplasts whose tissue is arranged as a photonic multilayer producing a characteristic strong blue reflectance associated to a wavelength selective absorption enhancement relevant for photosynthesis. In this work, we study how the photonic properties of iridoplasts are affected by light induced dynamic changes using realistic data extracted from previous reports. Our results show a reflectance red-shift from blue to green under increasing light intensity. Consequently, the light absorption enhancement induced by the photonic nanostructure is also redshifted. We also show that the photonic properties are resilient to biologically realistic levels of disorder in the structure. We extended this analysis to another photonic nanostructure-containing chloroplast, known as a bisonoplast, and found similar results, pointing towards similar properties in different plant species. We finally found that all types of chloroplasts can tune light absorption depending on light conditions. In general, our study opens the door to understanding how dynamic morphologies in chloroplasts can affect light scattering and absorption.