Look at this cool photo of the experimental set-up! The O2 microsensor is inserted 350 µm into the petiole tissue of a 2-week-old Brassica napus (canola) seedling. The O2 minioptode monitors the water O2 status during the experiment. These experiments are conducted to address the critique raised by the referees when we first submitted our paper to an international plant journal. Our RNA data strongly suggest that the leaf tissues do not experience hypoxia during submergence – even in the dark. However, we had no direct measurements of tissue O2 since the paper focused on leaf gas films (visible as a silvery sheen on the leaves also on the photo above).
Nevertheless, the lead scientist – Prof Mustroph in Bayreuth – suggested that we walked the extra mile and actually conducted a series of additional experiments and one of these is the tissue measurements of petiole O2 status in light or in darkness. I still have to complete the last set of replicates but the initial measurements clearly show that the petiole tissues decline slightly below air equilibrium during darkness – but not to any critical levels.
I hope to be able to complete these measurements today but if not, I need to come in tomorrow since the plants keep growing the they are supposed to be between 15- and 17-day-old in order to reflect the time points used for other data in the paper e.g., underwater photosynthesis, underwater respiration, gas film retention time and gene expression.