Chemical imaging of trichome specialized metabolites using contact printing and laser desorption/ionization mass spectrometry
Cell transfer by contact printing coupled with carbon-substrate-assisted laser desorption/ionization was used to directly profile and image secondary metabolites in trichomes on leaves of the wild tomato Solanum habrochaites. Major specialized metabolites, including acyl sugars, alkaloids, flavonoids, and terpenoid acids, were successfully detected in positive ion mode or negative ion mode, and in some cases in both modes. This simple solvent-free and matrix-free sample preparation for mass spectrometry imaging avoids tedious sample preparation steps, and high-spatial-resolution images were obtained. Metabolite profiles were generated for individual glandular trichomes from a single Solanum habrochaites leaf at a spatial resolution of around 50 μm. Relative quantitative data from imaging experiments were validated by independent liquid chromatography–mass spectrometry analysis of subsamples from fresh plant material. The spatially resolved metabolite profiles of individual glands provided new information about the complexity of biosynthesis of specialized metabolites at the cellular-resolution scale. In addition, this technique offers a scheme capable of high-throughput profiling of metabolites in trichomes and irregularly shaped tissues and spatially discontinuous cells of a given cell type.
KeywordsMass spectrometry imaging Glandular trichomes Plant specialized metabolites Single-cell analysis
The authors thank Christoph Benning for providing access to a light microscope, Greg Swain for providing glassy carbon, Sigma-Aldrich Supelco for the prototype high-performance LC column, the Michigan State University Center for Advanced Microscopy for assistance with optical imaging, Robert Last, Tony Schilmiller, Eran Pichersky, and Feng Shi for valuable discussions, and the RTSF Mass Spectrometry and Metabolomics Core at Michigan State University. Support for this research was provided by NSF grants IOS-1025636 and DBI-0604336 (R.L. Last principal investigator), and Michigan AgBioResearch.
- 7.Luckwill LC (1943) The genus Lycopersicon, an historical, biological, and taxonomic survey of the wild and cultivated tomatoes. University Press, AberdeenGoogle Scholar
- 13.Katsuragi T, Tani Y (2001) Single-cell sorting of microorganisms by flow or slide-based (including laser scanning) cytometry. Acta Biotechnol 21(2):99–115. doi: 10.1002/1521-3846(200105)21:2<99::Aid-Abio99>3.3.Co;2-O CrossRefGoogle Scholar
- 28.Varner JE, Ye Z (1994) Tissue printing. FASEB J 8(6):378–384Google Scholar
- 31.Gaston SM, Soares MA, Siddiqui MM, Vu D, Lee JM, Goldner DL, Brice MJ, Shih JC, Upton MP, Perides G, Baptista J, Lavin PT, Bloch BN, Genega EM, Rubin MA, Lenkinski RE (2005) Tissue-print and print-phoresis as platform technologies for the molecular analysis of human surgical specimens: mapping tumor invasion of the prostate capsule. Nat Med 11(1):95–101. doi: 10.1038/nm1169 CrossRefGoogle Scholar
- 32.McDowell ET, Kapteyn J, Schmidt A, Li C, Kang JH, Descour A, Shi F, Larson M, Schilmiller A, An LL, Jones AD, Pichersky E, Soderlund CA, Gang DR (2011) Comparative functional genomic analysis of Solanum glandular trichome types. Plant Physiol 155(1):524–539. doi: 10.1104/pp. 110.167114 CrossRefGoogle Scholar
- 35.Cha SW, Zhang H, Ilarslan HI, Wurtele ES, Brachova L, Nikolau BJ, Yeung ES (2008) Direct profiling and imaging of plant metabolites in intact tissues by using colloidal graphite-assisted laser desorption ionization mass spectrometry. Plant J 55(2):348–360. doi: 10.1111/j.1365-313X.2008.03507.x CrossRefGoogle Scholar