Identification of endogenous N-(3-indoleacetyl)aspartic acid in scots pine( Pinus sylvestris L.)by combined gas chromatography-mass spectrometry, using high-performance liquid chromatography for quantification

Abstract

N-(3-indoleacetyl)aspartic acid (IAAsp), a conjugate of the phytohormone 3-indoleacetic acid (IAA), was conclusively identified by combined gas chromatograhy-mass spectrometry (GC—MS) in dormant shoots of Scots pine ( Pinus sylvestris L.). A procedure based on reversed-phase liquid chromatography and flurescense detection is described for quantitative analysis of IAAsp levels in pine tissue. The current year's shoots of dormant seven-year-old trees of Scots pine contained 60 ng/g IAAsp fresh weight. The sensitivity of this method for IAAsp, applied to this material, was 1 ng, and 200 pg for pure standard. The preceding clean-up of the extract included the use of Amberlite XAD-7, a polyacrylic ester, which transfer organic compounds from a water phase to small volumes of organic solvents, an excellent alternative to the often used buffer-organic solvent extractions.