Pollen Metabolome Dynamics: Biochemistry, Regulation and Analysis

The metabolome of an organism represents the readout of its biochemistry comprising numerous and tightly regulated metabolic pathways. Experimental analysis of the metabolome and its interpretation in a biochemically and physiologically meaningful context is focused by the research field of metabolomics which has become an integral part of many systems biological studies. Pollen development, germination and tube growth comprise numerous steps of metabolic regulation resulting in significant metabolome dynamics. To unravel involved regulatory molecular processes and to promote the understanding of developmental reprogramming and stress tolerance mechanisms in pollen, it is crucial to quantitatively resolve dynamics in the pollen metabolome. Since these dynamics affect various substance groups with different physico-chemical properties, different experimental platforms are needed for robust compound identification and quantification. It has been shown that developmentally and stress-induced metabolic reprogramming in pollen significantly affects the redox homeostasis as well as metabolism of carbohydrates, amino acids, lipids, polyamines, flavonoids and phytohormones. In this chapter, mechanisms of metabolic reprogramming are summarized and discussed in the context of pollen development and stress exposure. Finally, it is discussed how these metabolome dynamics can be resolved methodologically in order to unravel molecular physiological mechanisms of pollen development.