An enhanced plant lipidomics method based on multiplexed liquid chromatography-mass spectrometry reveals additional...

Within the lipidome of plants a few bulk molecular species hamper the detection of the rest, which are present at relatively low levels. In addition, low-abundance species are often masked by numerous isobaric interferences, such as those caused by isoelemental species and isotopologues. This scenario not only means that minor species are underrepresented, but also leads to potential misidentifications and limits the structural information gathered by lipidomics approaches. In order to overcome these limitations we have developed a multiplexed liquid chromatography-mass spectrometry lipidomics platform able to achieve an enhanced coverage of plant lipidomes. The platform is based on a single extraction step followed by a series of ultra-performance liquid chromatography separations. Post-column flow is then directed to both a triple quadrupole analyzer for targeted profiling and a time-of-flight analyzer for accurate mass analysis. As a proof of concept, plants were subjected to cold or drought, which are known to trigger widespread remodeling events in plant cell membranes. Analysis of the leaf lipidome yielded 393 molecular species within 23 different lipid classes. This enhanced coverage allowed us to identify lipid molecular species and even classes that are altered upon stress, allowing hypotheses on role of glycosylinositolphosphoceramides (GIPC), steryl glycosides (SG) and acylated steryl glycosides (ASG) in drought stress to be addressed and confirming the findings from numerous previous studies with a single, wide-ranging lipidomics approach. This extended our knowledge on membrane remodeling during the drought response, integrating sphingolipids and sterol lipids into the current glycerolipid-based model.