Correlated production and consumption of chloromethane in the Arabidopsis thaliana phyllosphere

Abstract

Abstract Chloromethane (CH 3 Cl) is a toxic gas mainly produced naturally, in particular by plants, and its emissions contribute to ozone destruction in the stratosphere. Conversely, CH 3 Cl can be degraded and used as the sole carbon and energy source by specialised methylotrophic bacteria, isolated from a variety of environments including the phyllosphere, i.e. the aerial parts of vegetation. The potential role of phyllospheric CH 3 Cl-degrading bacteria as a filter for plant emissions of CH 3 Cl was investigated using variants of Arabidopsis thaliana with low, wild-type and high expression of HOL1 methyltransferase previously shown to be responsible for most of CH 3 Cl emissions by A . thaliana . Presence and expression of the bacterial chloromethane dehalogenase cmuA gene in the A . thaliana phyllosphere correlated with HOL1 genotype, as shown by qPCR and RT-qPCR. Production of CH 3 Cl by A . thaliana paralleled HOL1 expression, as assessed by a fluorescence-based bioreporter. The relation between plant production of CH 3 Cl and relative abundance of CH 3 Cl-degrading bacteria in the phyllosphere suggests that CH 3 Cl-degrading bacteria co-determine the extent of plant emissions of CH 3 Cl to the atmosphere.