Barley root exudates collection and primary metabolite profiling

Abstract Plant exudates are one of the main drivers for the proliferation of the rhizosphere microbiota. We developed a protocol to quantify primary metabolites in exudates of the global crop barley. We used 2- and 3-week-old barley plants grown in sterilised sand and their root exudates were collected for 6 hours in ddH2O water to avoid degradation/transformation of the compounds. These samples were used to determine total carbon and total nitrogen by Dumas. Finally, we profiled primary metabolites in collected exudates by gas chromatography/mass spectrometry (GC-MS).