How did carnivorous plants evolve their love for meat? Scientists have been puzzled how these carnivorous plants developed these behavior, as it is often the animals that eat plants for food and not the other way around.
Now, a new study published in Nature Ecology & Evolution sheds light on how these leafy meat eaters became predators.
For the new study, biologist Victor Albert, from the University at Buffalo, and colleagues have found that the genetic changes linked to carnivory in Asian, Australian, and American pitcher plants.
Venus Flytrap And The Pitcher Plant
The Venus flytrap and the pitcher plant are among the most popular of meat-eating plants. The Venus flytrap has jaws that snap shut to capture its prey. The pitcher plant, on the other hand, traps insects into its cup-shaped leaf with slippery sides by luring the potential prey to the sweet nectar at the base of the pitcher.
Once the prey gets into the bottom of the cup, it gets stuck in the liquid. As the insect struggles to escape, the digestive enzymes of the plant begin to break down its body, eventually becoming the carnivorous plants' meal and providing the nutrients needed by the pitcher plant to survive in a resource-poor environment.
Carnivorous Plants Underwent Similar Genetic Changes
For the new study, researchers initially focused on the Australian pitcher plant (Cephalotus follicularis). After sequencing the plant's' DNA and comparing the results with those of the digestive enzymes of the American and Asian pitcher plants, the researchers concluded that while all three of these meat-loving plants evolved in distantly related lineages, they became carnivorous because of similar genetic changes that involve key enzymes.
The analysis hinted that over the course of their evolution, the plant protein in these three species of meat-eating plants that was originally involved in protecting the plants against disease and other stresses developed the digestive enzymes present in predatory plants today.
The enzymes include basic chitinase, which is responsible for breaking down chitin, the major component on the hard exterior exoskeletons of insects, and purple acid phosphatase, which allows the plants to get phosphorous, a crucial nutrient from their prey's body parts.
Researchers also found that a fourth carnivorous species, the lance-leaved sundew, appears to share this same evolutionary road with the pitcher plants.
"Analysis of digestive fluid proteins from C. follicularis and three other carnivorous plants with independent carnivorous origins revealed repeated co-options of stress-responsive protein lineages coupled with convergent amino acid substitutions to acquire digestive physiology," the researchers wrote in their study, which was published on Feb. 6.
"These results imply constraints on the available routes to evolve plant carnivory."
Researchers said that their findings represent an example of the so-called convergent evolution, through which unrelated species evolve independently to develop similar traits.
"It suggests that there are only limited pathways for becoming a carnivorous plant," Albert said. "These plants have a genetic tool kit, and they're trying to come up with an answer to the problem of how to become carnivorous. And in the end, they all come up with the same solution."