Scientists have figured out how plants called “living stones” get enough sunlight even though they grow partially underground.
The little succulents survive in the blazing deserts and rocky ground of southern Africa by blending in with surrounding pebbles to avoid being eaten and by burying themselves underground.
The study shows that Lithops combine a top surface with “windows” of translucent tissue that allows light through to photosynthetic tissues deep in the underground portion of the leaf, with a biochemical sunscreen to block out harmful UV light.
To offset damage associated with too much sunlight, the plants also use a protective mechanism known as non-photochemical quenching in the above-ground parts of the leaves.
The below-ground parts of the leaves are adapted more towards a shaded way of life, with highly specialized cell shapes, tissue chemistry, and crystalline deposits to help maximize limited light levels.
“This work highlights the incredible adaptations that have evolved in ‘living stones’ in response to the blazing sunshine they experience in their desert habitat,” says Katie Field, who carried out the research with Rachel George at the University of Sheffield and Matthew Davey at the University of Cambridge. Their findings appear in PLOS ONE.
“Unlike most members of the plant kingdom, these amazing little plants photosynthesize underground. We’ve discovered that by using a sunscreen and moving their photosynthetic machinery beneath the soil, “living stones” manage to avoid the effects of too much sun yet simultaneously maximize photosynthesis through previously unrecorded mechanisms. This suits them for life both in full sun and in full shade, at the same time.
“This research helps us to understand how plants cope with extreme environments on Earth and may play a part in future development of efficient crop plants.”
Source: University of Sheffield