In a new study led by the University of Würzburg, scientists have found that carnivorous plants share a basic set of genes. The researchers traced the carnivorous genes back to a duplication event that occurred millions of years ago.
Plants can generate energy through photosynthesis, but there are some plants that prefer to trap and eat insects instead. The current study is shedding new light on how carnivorous plants evolved.
The researchers sequenced the genomes of three carnivorous plant species: the Venus flytrap Dionaea muscipula, the waterwheel plant Aldrovanda vesiculosa, and the spoon-leaved sundew Drosera spatulata.
Despite the fact that these three species all belong to the sundew family, they have each adapted to unique habitats. The plants have also developed different trapping mechanisms.
In Dionaea and Aldrovanda, the ends of the leaves contain sensitive hairs that signal the leaves to snap shut, trapping whatever is inside. On the other hand, the sundew uses sticky tentacles on its leaves to catch prey.
The carnivorous plants may have different lifestyles, but the researchers found that their most essential genes are the same.
“The function of these genes is related to the ability to sense and digest prey animals and to utilise their nutrients,” said study co-author Rainer Hedrich.
“We were able to trace the origin of the carnivory genes back to a duplication event that occurred many millions of years ago in the genome of the last common ancestor of the three carnivorous species,” added study co-author Jörg Schultz.
The duplication of the entire genome provided an opportunity for new genetic material to arise, changing the structure and function of future descendants on a molecular level.
The researchers expected to find that carnivorous plants would require a larger set of genes. Instead, the three species were found to have substantially fewer genes. For example, most plants have between 30,000 and 40,000 genes, yet sundew has only 18,111.
“This can only mean that the specialization in animal food was accompanied by an increase in the number of genes, but also a massive loss of genes,” said Hasebe.
According to the researchers, most of the genes required for the insect traps can also be found in slightly different form in normal plants.
“In carnivorous plants, several genes are active in the trapping organs, which in other plants have their effect in the root. In the trapping organs, these genes are only switched on when the prey is secure,” said Hedrich.
This explains why the Venus flytrap and sundew have small roots and the waterwheel has no roots.
Next, the researchers plan to investigate the trapping function and compare its molecular structure among various carnivorous plants.
The study is published in the journal Current Biology.