Metabolic imaging: Analysis of different sections of white Asparagus officinalis shoots using high-resolution mass spectrometry.

Many plant metabolism processes are currently not completely understood despite the numerous studies. These include the events in plant shoots and especially in the apical meristem. To understand the various mechanisms on a molecular level, a combined approach of target and non-targeted fingerprinting analysis was worked out on different white asparagus spear segments using high resolution mass spectrometry. By means of various multivariate analysis strategies, numerous distinctions within diverse substance classes were observed. While most of the investigated metabolites were present in relatively higher concentrations in the tip of the asparagus spears, others were more accumulated at the bottom, some, in turn, did not show any concentration differences along the shoot. Using pathway analysis, the most significant metabolites were classified in the biological context. To our knowledge for the first time, a non-targeted metabolomics approach is used with the aim of metabolic profiling of plant sprouts.

Effects of elevated CO2 concentration on leaves and berries of black elder (Sambucus nigra) using UHPLC-ESI-QTOF-MS/MS and gas exchange measurements.

The effect of elevated CO2 concentration on leaves of black elder (Sambucus nigra) was investigated based on leaf gas exchange, chlorophyll content as well as on the analysis of the underlying metabolite profile of the fruits. The measurements were carried out once a month over a period of time of 4 months. The CO2 uptake rate, the transpiration rate and stomatal conductance were significantly higher in plants under ambient CO2, in comparison to plants grown under elevated CO2 concentrations. On the other hand, at the initial phase of the experiments, the photosynthesis rate was higher in CO2 loaded plants compared to plants grown under normal conditions. Remarkably, after about one month a habituation effect could be observed leading to a decrease of the photosynthetic efficiency approaching again the normal level. To understand the observed effects on a molecular level, non-targeted fingerprinting analysis was performed on the ripe elder berries using LC-qToF-ESI-MS(/MS). Differences in the composition of various phenols, triglycerides and PC (36:5) as well as a stigmasterole-derivate could be detected. In contrast, central metabolic pathways such as photosynthesis, the tricarboxylic acid cycle as well as the biosynthesis of essential amino acids obviously are not considerably affected.