INTRUDER ALERT: Buds growing from under the bark in a yew tree (1) split the wood open down to the vascular tissue, allowing pathogenic fungi (red) to enter. Endophytic fungi (blue) grow towards the crack to combat the invasion (2). The pathogen gives off chloromethane (red cloud) as it starts to decay the surrounding wood (3). This induces the endophytes to release hydrophobic spheres (gray balls) containing the antifungal chemical Taxol. The chloromethane encounters the spheres and causes the Taxol to be released (blue spray), killing the pathogenic fungi (4). The hydrophobic spheres also accumulate and seal up the crack to prevent future infection (5).
View image larger: JPG© LISA CLARK
The paper
S.S.M. Soliman et al., “An endophyte constructs fungicide-containing extracellular barriers for its host plant,” Curr Biol, 25:2570-76, 2015.
Taxol (paclitaxel) is a potent cell-division inhibitor and anticancer drug produced naturally by yew trees (Taxus) and their resident nonpathogenic fungi, called endophytes. In 2008, Sameh Soliman, a PhD student in Manish Raizada’s lab at the University of Guelph in Ontario, was trying to coax a Taxus endophyte (Paraconiothyrium) to ramp up its Taxol production. To Soliman’s surprise, he not only detected Taxol in the growth media, but also a resinous substance that turned out to be hydrophobic spheres containing the compound. “It was a really unique structure,” says Soliman.
To find out more, Soliman and Raizada stepped out of the lab and into the ...
