Tuesday, 28 September 2010

Fungus Fart



This charming little story comes care of friend and colleague Jim Croft, who is always on the look out for botanical novelty and novel botanicalty.

I wasn't sure whether to use Jim's original title, Fungi Farts, or the more adjectival Fungal Farts. In the end I went with the more classical approach, borrowing from Titus Groan.

The story comes from the latest edition of the Proceedings of the National Academy of Science, via New Scientist, via Jim.

But enough of the prelude. It seems that some fungi fart, or more politely, 'produce wind'.

They do this to spread their spores further, so they can find new hosts to bother or debri to compost. In general they use the wind, just like many flowering plants do when they produce winged and feathery seeds. But as New Scientist point out, sometimes there just isn't a good breeze.

Researchers at the University of California, in Berkeley, lead by Marcus Roper, have been studying what I used to call ascomycetes. Goodness knows whether they are still called this but all ascomycetes produce spores in little sacks called 'asci' - hence the name.

These asci-producing fungi have a range of vessels for holding and releasing these spore sacks, and about 8,000 of them produce what are called 'apothecia'. These apothecia are cup-shaped structures lined with asci. So there you go. That's pretty much what I remember along with what New Scientist provides as background.

The problem for any fungus is that its spores are small, extremely small. If they were to be ejected one-by-one they might only travel a few millimetres and it would be a pretty energy intensive process to fire of each ascus.

Instead it seems that some species, and maybe all, use a shot of air to fire off all their spores.

Roper and his team have been filming the spore ejections, as they call them, from fungus called Sclerotinia slerotiorum, which causes White Mold and other nasty rashes and diseases in a range of crop plants.

What they found was by ejecting thousands of spores at the one time (from their asci in the apothecia...) a small jet of air resulted in the spores travelling 10 centimetres rather than 3 millimetres if a single asci releases alone.

It's thought a drop in air pressure triggers this syncronised release, starting with a few 'pioneer spores' and then leading to changes in the apothecia tissue causing the mass ejection.
While it's fun to use this research as an excuse to head a posting with Fungus Farts, something like $1 billion is spent each year in the US to protect crops like tomotoes and sunflowers from Sclerotinia slerotiorum. Marcus Roper tells New Scientist that understanding disperal better may lead to vastly improved control of this troublesome pathogen.

Image: What I hope is an ascomycete, beside Roses Gap Road in the Grampians, in Victoria, about this time last year. I know it looks a lot like a chocolote confectionary of some kind, but it certainly isn't that.