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Abstract:
Developmental senescence is a coordinated physiological process in plants and is critical for nutrient redistribution from senescing leaves to newly formed sink organs including young leaves and developing seeds. Progress has been made concerning genes involved and the regulatory networks controlling senescence. The resulting complex metabolome changes during senescence have not been investigated in detail yet. Therefore, we conducted a comprehensive profiling of metabolites including pigments, lipids, sugars, amino acids, organic acids, nutrient ions, and secondary metabolites and determined approximately 260 metabolites at distinct stages in leaves and siliques during senescence in Arabidopsis thaliana. This provided an extensive catalogue of metabolites and their spatio-temporal co-behavior with progressing senescence. Comparison to silique data provides cues to source-sink relations. Further, we analysed the metabolite distribution within single leaves along the basipetal sink-source transition trajectory during senescence. Ceramids, lysolipids, aromatic amino acids, branched chain amino acids and stress induced amino acids accumulated, and an imbalance of Asn/Asp, Glu/Gln and nutrient ions in the tip region of leaves was detected. Furthermore, the spatio-temporal distribution of TCA cycle intermediates was already changed in the pre-senescent leaves and glucosinolates, raffinose and galactinol accumulated in the base region of leaves with proceeding senescence. These results are discussed in the context of current models of the metabolic shifts occurring during developmental and environmentally induced senescence. As senescence processes are correlated to crop yield, the metabolome data and the approach provided here can serve as a blueprint for the analysis of traits and conditions linking crop yield and senescence.
