How plants evolved into carnivores

Ewen Callaway in Nature:

Any insect unlucky enough to land on the mouth-like leaves of an Australian pitcher plant will meet a grisly end. The plant's prey is drawn into a vessel-like ‘pitcher’ organ where a specialized cocktail of enzymes digests the victim. Now, by studying the pitcher plant's genome — and comparing its insect-eating fluids to those of other carnivorous plants — researchers have found that meat-eating plants the world over have hit on the same deadly molecular recipe, even though they are separated by millions of years of evolution.

…Australian pitcher plants produce deadly ‘pitcher’ leaves — which resemble a toothy grin — as well as flat leaves. After sequencing the species’ genome, Albert’s team identified genes that are activated differently between the pitcher-like leaves and the plant's other, non-carnivorous, leaves. These included genes involved in making starches and sugars that may help to produce the nectar that lures insects to their deaths, as well as genes encoding waxy substances that may make it hard to escape from the pitcher. To determine how pitchers eat their prey, the researchers sampled the digestive cocktail from Cephalotus and several other unrelated carnivorous plants and identified a total of 35 proteins, using mass spectrometry. Many of the proteins are related to those that other flowering plants use to fend off pathogens^2–5. For instance, plants typically produce enzymes that break down a polymer called chitin as a defence against fungi, which make their cell walls out of the chemical. But Albert suspects that Australian pitchers and other carnivorous plants have repurposed the enzyme to digest insect exoskeletons, which are also made of chitin.

More here.