Flesh-eating plants have evolved to lure flies with the putrid smell of rotting meat, thanks to a genetic mutation that produces dimethyl disulfide, a stinky chemical associated with carrion.
The Stink of Death: How Plants Lure Flies with Rotting Flesh
Some flowers smell like death, and for the same reason. Malodorous members of the Eurya, Asarum, and Symplocarpus genera independently evolved changes in an enzyme that helps them attract pollinating flies with the unlovely smell of rotting meat.
Flesh-eating plants, also known as carnivorous plants, obtain essential nutrients by capturing and digesting insects, small animals, or even other plants.
These plants have adapted to grow in nutrient-poor soil, where water and sunlight are abundant but necessary minerals are scarce.
Examples of flesh-eating plants include Venus flytraps (Dionaea muscipula) and pitcher plants (Nepenthes spp.).
They use modified leaves, such as snap traps or pitfall traps, to capture prey.
The digestive process breaks down the captured organisms into a nutrient-rich soup that nourishes the plant.
The Science Behind the Stench
For years, scientists have been puzzled by how plants produce the carrion stench, usually associated with bacteria feasting on decaying corpses. Researchers in Japan used biochemistry and molecular and evolutionary genetics to determine that three unrelated plant lineages hit on the same evolutionary trick to produce this foul odor.
First, a gene called SBP1 was duplicated, which is a common occurrence in the evolution of most organisms, including humans. Then, the extra copy of the gene mutated, swapping a few amino acids in the enzyme it produces. This mutation led to the production of dimethyl disulfide, a stinky chemical that smells like rotten animal carcasses or feces.
The Unique Case of Symplocarpus renifolius
The Asian skunk cabbage (Symplocarpus renifolius) needed only two amino acid swaps to become malodorous. This is notable because other plants, such as the wild ginger (Asarum simile) and the East Asian eurya shrub (Eurya japonica), required three changes in their enzymes.
The Role of Methanethiol
SBP1 makes an enzyme that helps break down methanethiol, a chemical itself that is smelly. The original enzyme breaks methanethiol into hydrogen peroxide, hydrogen sulfide, and formaldehyde. However, the tweaked enzymes from stinky plants instead link two methanethiol molecules into dimethyl disulfide, responsible for the much more putrid scent of rotten meat.
Evolutionary Pressure
Among Asarum species, the ability to make dimethyl disulfide was gained and lost more than 18 times. The researchers found evidence that plants are under evolutionary pressure to make this foul-smelling molecule, which may attract more flies to pollinate them.
Evolutionary pressure is the driving force behind the adaptation and diversification of species.
It arises from the interaction between an organism's genetic makeup and its environment, leading to the survival and reproduction of individuals with favorable traits.
Natural selection, mutation, and gene flow are key mechanisms that contribute to evolutionary pressure.
In response to environmental pressures such as predation, climate change, or resource scarcity, populations adapt through genetic variation and natural selection, resulting in the evolution of new species.
- sciencenews.org | Putrid
