Nutrient-poor habitats have led some plants to become carnivores and to capture insects by trapping them inside leaves. Once inside, the digestive fluids of the vegetable are responsible for undoing the meat of their prey and their exoskeletons to take advantage of the nitrogen and phosphorus they need .
Curiously, the carnivorous plants of Australia, Asia and America , despite having evolved separately, use this same method to nourish themselves. A study led by the National Institute of Biology of Japan, with the participation of the University of Barcelona (UB) and published in Nature Ecology & Evolution 2017, identified the genetic changes that have made it possible to adapt to the carnivorous diet of three plant species: Australian Cephalotus follicularis , Asian Nepenthes alata and American Sarracenia purpurea .
They first sequenced the genome of Cephalotus follicularis , a small carnivorous plant native to Australia that has modified, jar-shaped leaves that function as a well into which insects fall for food. Cephalotus has well differentiated insectivorous leaves –the ones that serve as a trap– from non-insectivorous leaves, similar to those of normal plants. The genome of this species is relatively large , almost half the human genome. The researchers identified more than 36,000 genes.
According to Julio Rozas, from the Department of Genetics, Microbiology and Statistics of the UB, ” the ability of carnivorous plants to eat animals in impoverished soils is the result of the action of natural selection that has promoted several genetic changes on the same set of Genes By comparing the genes that are differentially expressed in the two types of leaves, this research has identified the genetic changes associated with the carnivorous diet in plants. “
An example of evolutionary convergence
Genetic analyzes show that, during their evolution towards the carnivorous diet, the leaves that trap insects have acquired new enzymatic functions. There is a specific group of proteins that have evolved to act as digestive enzymes, according to Pablo Librado, another of the authors, who works at the Center for Geogenetics at the University of Copenhagen. Over time, in all three species, the families of plant proteins that originally aided in self-defense against disease and other threats became today’s digestive enzymes , such as basic chitinase – capable of breaking down chitin, the main component of the exoskeletons of prey–, and purple acid phosphatase –which allows plants to obtain phosphorus from decomposed bodies–.
It is as if these plants have a genetic toolbox and are trying to find an answer to become carnivorous. In the end, they all come up with the same solution. The case of insectivorous plants is a clear example of evolutionary convergence, probably due to the strong biological restrictions imposed by extreme ecosystems.
Source: SINC
Referencia: Kenji Fukushima et al. “Genome of the pitcher plant Cephalotus reveals genetic changes associated with carnivory” NatureEcology & Evolution 6 de febrero de 2017
