Capturing in Vivo Plant Metabolism by Real-Time Analysis of Low to High Molecular Weight Volatiles

We have deployed an efficient secondary
electrospray ionization
source coupled to an Orbitrap mass analyzer (SESI-MS) to investigate
the emissions of a Begonia semperflorens. We document how hundreds of species can be tracked with an unparalleled
time resolution of 2 min during day–night cycles. To further
illustrate the capabilities of this system for volatile organic compounds
(VOCs) analysis, we subjected the plant to mechanical damage and monitored
its response. As a result, ∼1200 VOCs were monitored displaying
different kinetics. To validate the soundness of our in vivo measurements,
we fully characterized some key compounds via tandem mass spectrometry
(MS/MS) and confirmed their expected behavior based on prior gas chromatography/mass
spectrometry (GC/MS) studies. For example, β-caryophyllene,
which is directly related to photosynthesis, was found to show a periodic
day–night pattern with highest concentrations during the day.
We conclude that the capability of SESI-MS to capture highly dynamic
VOC emissions and wide analyte coverage makes it an attractive tool
to complement GC/MS in plant studies.