Fast phenotyping of LFS-silenced (tearless) onions by desorption electrospray ionization mass spectrometry (DESI-MS).
Fast 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 MS(2) 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.
The New Zealand Institute for Plant and Food Research Limited, Christchurch, New Zealand. nigel.joyce@plantandfood.co.nz
Nigel I
NI
Joyce
Colin C
CC
Eady
Patrick
P
Silcock
Nigel B
NB
Perry
John W
JW
van Klink
D049452:Green Fluorescent Proteins / Q000032:analysis / Q000737:chemistry; D019746:Intramolecular Oxidoreductases / Q000032:analysis* / Q000737:chemistry; D019697:Onions / Q000737:chemistry*; D010641:Phenotype; D018515:Plant Leaves / Q000737:chemistry; D011522:Protons; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013455:Sulfur
D011522:Protons; D049452:Green Fluorescent Proteins; D013455:Sulfur; D019746:Intramolecular Oxidoreductases; C570346:lachrymatory factor synthase, Allium cepa