[thedoc (OP)]

In 2006, scientists discovered that plants produce significant amounts of the greenhouse gas, methane.  The research caused quite a stir and it led to a rethink about the role of plants and forests in global warming.  One of the questions that needed answering is how plants emits methane.  And so, a research group at the University of Edinburgh set up the aptly named, ‘Methane Project’...
Read a transcript of the interview by clicking here

or [chapter podcast=4067 track=12.08.05/Naked_Scientists_Show_12.08.05_10541.mp3] Listen to it now[/chapter] or [download as MP3]

[Jens]

The default assumption is that the methan is produced by methanogenic archaea.
Those archea have a very special and difficult metabolism und produce large amounts of methan as a part of their energy metabolism (also in the ruman of cows). Personally I do not know any other pathway which leads to methan. But of course plants have a very rich metabolism. So it might be that in a strange side pathway they produce methan. However, plants a reducing CO2 via a lot of sunlight energy consumption to produce sugar and basically all their carbon containing biomolecules. From this perspective it is a giant waste of energy for a plant to release the most reduced form of carbon which is CH4 (methan) into the environment.

Out of the interview it was not clear, what were actually the hints that plants are producing the methan and not methanogenic archaea in the soil the plants are growing.
Are there any hints?