Monday, January 9, 2012


First plant to use buried leaves to catch worms found

 Scanning electron micrograph of nematodes for dinner (<i>Image: Caio G. Pereira/Rafael S. Oliveira et al/PNAS</i>)
Scanning electron micrograph of nematodes for dinner (Image: Caio G. Pereira/Rafael S. Oliveira et al/PNAS)
A sticky end awaits worms that stray too close to a scrawny-looking plant unique to Brazil. Philcoxia minensis is the first carnivorous plant discovered to trap and devour prey in the soil with the help of sticky leaves prodded below the surface.
Earlier investigations had shown that P. minensis's tiny subterranean leaves, each just 1.5 millimetres wide, were covered with grains of sand and the corpses of nematode worms.
Now, Rafael Silva Oliveira of the State University of Campinas in Sao Paulo, Brazil and his colleagues say they have proof that the plants qualify as carnivores by digesting the nematodes.
The team placed P. minensis in soil filled with nematodes containing the rare isotope nitrogen-15. Oliveira's team showed that the leaves that snared the nematodes rapidly absorbed the isotope. Within a day, 5 per cent of the weight of isotope provided had been assimilated into the leaves, with 15 per cent gone after two days.
Oliveira also discovered that the leaves were covered with phosphatases, enzymes that rapidly break down flesh, allowing the plants to digest it.

Nematode traps

 "Undoubtedly, the most unique feature about how Philcoxia kills its prey is the underground placement of leaves that function as effective nematode traps," says Oliveira.
Oliveira says that the strategy makes sense in the plant's barren, rocky environment – despite the apparently counterproductive adaption of burying light-harvesting leaves underground in the dark. The team now hope to investigate how other plants in the bleak habitat secure their nutrients.
"This is a beautiful discovery," says Walter Federle who studies carnivorous plant  at the University of Cambridge. "It would be interesting to find out if the traps capture other soil animals, whether the plant specifically attracts nematodes, and whether the worms are mechanically trapped in the sticky secretion or killed by a toxin."

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1114199109

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