Comparative structural profiling of trichome specialized metabolites in tomato (Solanumlycopersicum) andS. habrochaites: acylsugar profiles revealed by UHPLC/MS and NMR.
Many plants accumulate large quantities of specialized metabolites in secretory glandular trichomes (SGTs), which are specialized epidermal cells. In the genusSolanum, SGTs store a diverse collection of glucose and sucrose esters. Profiling of extracts from two accessions (LA1777 and LA1392) ofSolanum habrochaitesusing ultra-high performance liquid chromatography-mass spectrometry (UHPLC/MS) revealed wide acylsugar diversity, with up to 11 isomers annotated for each individual elemental formula. These isomers arise from differences in ester chain lengths and their positions of substitution or branching. Since fragment ion masses were not sufficient to distinguish all isomers, 24 acylsucroses were purified fromS. habrochaitesaccessions and cultivated tomato (Solanum lycopersicumM82) and characterized using NMR spectroscopy. Two-dimensional NMR spectra yielded assignments of positions of substitution of specific acyl groups, and locations of branching. The range of substitution was wider than reported earlier, and in contrast to previous reports, tetra- and penta-acylsucroses were substituted at position 2 with acyl groups other than acetate. Because UHPLC/MS fails to yield sufficient information about structure diversity, and quantitative NMR of acylsugar mixtures is confounded by structural redundancy, the strategic combination of NMR and UHPLC/MS provides a powerful approach for profiling a class of metabolites with great structural diversity across genotypes.
Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, Biochemistry Building, Room 212, East Lansing, MI 48824 USA.
Banibrata
B
Ghosh
Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, Biochemistry Building, Room 212, East Lansing, MI 48824 USA.
Thomas C
TC
Westbrook
Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, Biochemistry Building, Room 212, East Lansing, MI 48824 USA.|Department of Chemistry, Michigan State University, East Lansing, MI 48824 USA.
A Daniel
AD
Jones
Acylsugars; Collision-induced dissociation; Comparative profiling; Glandular trichomes; Metabolite identification