Shade-loving Begonia plants have iridescent blue leaves as a result of a cell organelle that allows them to efficiently harvest light in low-light conditions.

Credit: M. Jacobs et al./Nature Plants

Plants rely on organelles called chloroplasts for photosynthesis. Heather Whitney at the University of Bristol, UK, and her colleagues used light and electron microscopy to study the structure of a variant of these organelles, called an iridoplast, in the surface layers of Begonia plants (hybrid of B. grandis and B. pavonina, pictured). The team found that the iridoplasts' membranes are stacked in piles of three or four in a highly regular manner — a structure not seen in normal chloroplasts.

Data modelling showed that this structure allows iridoplasts to absorb predominantly green light, which is abundant in forest shade, and enhances photosynthetic efficiency by up to 10%.

Nature Plants (2016)