Fragmentation pathway studies of several plant hormones using an electrospray ionization-quadrupole/time-of-flight mass spectrometer

Auxins, cytokinins (CKs), gibberellins (GAs), and abscisic acid (ABA) are four classes of plant hormones, which play important roles in phytophysiology. However, few mass spectrometric fragmentation pathway studies of these compounds have been performed using a high-resolution mass spectrometer. Therefore, there is an urgent need to research the fragmentation pathways of classic plant hormones. In this study, the fragmentation pathways of four types of plant hormones were studied by employing an electrospray ionization-quadrupole/time-of-flight (ESI-Q/TOF) mass spectrometer. The accurate masses of the ions in the mass spectrometer (MS) and the product ions in the MS/MS were combined and used to obtain the MS fragmentation pathways of these compounds. The exact mass-to-charge ratio for each product ion was determined to deduce the elemental compositions for each compound. Most of the ions were assigned according to the collected high-resolution accurate mass data, and typical fragmentation pathways of the four classes of plant hormones were proposed. Furthermore, a comprehensive MS/MS spectra library of the plant hormones was established for the first time using ESI-Q/TOF. For instance, a characteristic mass signal of m/z 130 was identified for the product ions of the indole 3-acetic acid homologue auxins in the positive ion mode and for the characteristic neutral loss of CO2CO2H2O for gibberellin in the negative ion mode. These findings are valuable for the identification of a variety of plant hormones and could also provide a basis for developing MS-based methods of detecting or screening a target class of plant hormones in plant extracts.

Figure optionsDownload high-quality image (122 K)Download as PowerPoint slideHighlights
► The MS fragmentation pathways of several plant hormones were studied.
► Our experimentation is based on the high-resolution TOF mass spectrometry studies.
► m/z 130 was the characteristic product ions of the IAA homologue auxins in ESI+.
► Characteristic neutral loss of CO2CO2H2O for gibberellins in the ESI−.