an appraisal on the source-to-sink relationship in plants: an application of desorption electrospray ionization mass spectrometry imaging

Amino acids/ureides and carbohydrates are the main nutrients for the plants growth. these metabolites are continuously translocated through the plant organism via well-known transportation mechanisms. the well-established source-to-sink relationship involves the transfer of these nutrients from mature (source) to young (sink) leaves. desorption electrospray ionization mass spectrometry imaging (desi-msi) is used herein to determine the spatial distribution of amino acids/ureides and carbohydrates in the imprintings of mentha × piperita l. leaves at three distinct maturation stages: young, expanding, and mature. hence, chemical images of some typical carbohydrates (glucose, sucrose, sorbitol/mannitol) and free amino acids/ureides (phenylalanine, leucine, histidine, aspartate, asparagine, tyrosine, glutamate, allantoic acid) clearly point to a source-to-sink relationship, as the young leaves are the final destination for some of these key metabolites. these results therefore reveal the high potential of desi-msi to investigate biochemical processes in plants, a still underexplored area.