Toward the quantitation of plant hormones from single cells

Abstract

To understand the mechanisms by which plant hormones regulate physiological processes, it is crucial to exactly know their endogenous concentrations at cellular levels.　We recently established a method to determine the levels of abscisic acid （ABA） and jasmonoyl-isoleucine （JA-Ile） from single cells by employing “live-single cell mass spectrometry （MS）”.　Single cell contents were taken from Vicia faba leaves by using nano-electrospray ionization tips under a stereomicroscope.　Stable isotope-labeled hormones were then added to the samples as internal standards to normalize ionization efficiencies and quantify the hormone levels.　The samples were directly introduced into a mass spectrometer and subjected to MS/MS analysis.　With careful validation of the data obtained, we succeed in the detection of stress-induced accumulation of ABA and JA-Ile from living single cells.　In this article, we summarize our challenge to establish a method to quantify plant hormones by single cell MS analysis.