In situ separation and visualization of isomeric auxin derivatives in Arabidopsis by ion mobility mass spectrometry imaging.

In situ separation and visualization of synthetic and naturally occurring isomers from heterogeneous plant tissues, especially when they share similar molecular structures, are a challenging task. In this study, we combined the ion mobility separation with desorption electrospray ionization mass spectrometry imaging (DESI-IM-MSI) to achieve a direct separation and visualization of two synthetic auxin derivatives, auxinole and its structural isomer 4pTb-MeIAA, as well as endogenous auxins from Arabidopsis samples. Distinct distribution of these synthetic isomers and endogenous auxins in Arabidopsis primary roots and hypocotyls was achieved in the same imaging analysis from both individually treated and cotreated samples.

New fluorescently labeled auxins exhibit promising anti-auxin activity.

The plant hormone auxin is a key player in the regulation of plant growth and development. Despite numerous studies devoted to understanding its role in a wide spectrum of physiological processes, full appreciation of its function is linked to a comprehensive determination of its spatio-temporal distribution, which plays a crucial role in its mode of action. Conjugation of fluorescent tracers to plant hormones enables sensitive and specific visualization of their subcellular and tissue-specific localization and transport in planta, which represents a powerful tool for plant physiology.