A little while ago we looked at auxotrophic algae getting a helping hand from bacteria; now we’ll take a look at ‘proper plants’ that get a little help from animals (in a sort of mixotrophy). But it’s not exactly willing on the animal’s part! We talk of those amazing angiosperms known as carnivorous plants (‘the most wonderful plants in the world’) who supplement their nitrogen requirements by digesting animals that they often trap.
Impressive as that is, a danger with this external digestion is that other opportunistic organisms could help themselves to the products of that expensively-produced enzyme catabolism, thereby increasing the costs of this behaviour to the carnivore. Well – and surely providing evidence that either plants are clever or that they’ve been intelligently designed – Wolfram Adlassnig et al. report that several carnivorous plant species engage in endocytosis of intact proteins in addition to absorption of digested products.
A potential advantage of this endocytosis (a cellular process whereby cells internalise materials by ‘engulfing’ them rather than absorbing them across the cell membrane) is that it reduces the need to release enzymes into the environment (which proteins are themselves expensively-produced, nitrogen-rich molecules that are presumably not resorbed) and so lessens the chances of other organisms appropriating the results of the plant’s extra-corporeal digestive activities. Such endocytotic behaviour was detected in Nepenthes, Drosera, Dionaea, Aldrovanda, Drosophyllum and Cephalotus (but not in Genlisea and Sarracenia).
Yes, I know what you’re thinking. No, not that this is a nice bit of plant cell biology/ecology (which it is!), but what on earth is a non-arabidopsis paper doing in the Plant Journal…? Well, maybe that organ’s own coverage will one day be as broad as the Annals of Botany’s, which would be evidence for plant evolution!