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Fast Phenotyping of LFS-Silenced (Tearless) Onions by Desorption Electrospray Ionization Mass Spectrometry (DESI-MS)
journal contribution
posted on 2013-02-20, 00:00 authored by Nigel I. Joyce, Colin C. Eady, Patrick Silcock, Nigel
B. Perry, John W. van KlinkFast MS techniques have been applied to the analysis
of sulfur
volatiles in Allium species and varieties
to distinguish phenotypes. Headspace sampling by proton transfer reaction
(PTR) MS and surface sampling by desorption electrospray ionization
(DESI) MS were used to distinguish lachrymatory factor synthase (LFS)-silenced
(tearless; LFS−) onions from normal, LFS-active (tear-inducing;
LFS+), onions. PTR-MS showed lower concentrations of the lachrymatory
factor (LF, 3) and dipropyl disulfide 12 from tearless onions. DESI-MS of the tearless onions confirmed the
decreased LF 3 and revealed much higher concentrations
of the sulfenic acid condensates. Using DESI-MS with MS2 could distinguish zwiebelane ions from thiosulfinate ions. DESI-MS
gave reliable fast phenotyping of LFS+ versus LFS– onions by
simply scratching leaves and recording the extractable ions for <0.5
min. DESI-MS leaf compound profiles also allowed the rapid distinction
of a variety of Allium cultivars to aid plant breeding
selections.