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

Abstract

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.