Quantitative ambient mass spectrometry imaging in plants: A perspective on challenges and future applications

Mass spectrometry imaging (MSI) is a powerful approach to understanding plant chemistry in a native context because it retains key spatial information that is otherwise averaged out, permitting chemical compounds to be mapped to specific tissue structures. Identifying the spatial localization of compounds in plant tissues has provided insights into the synthesis and functional role of a wide range of endogenous molecules. The power and utility of MSI is being further expanded through the development of quantitative methodologies, which enable relative and absolute quantification of target analytes. Here, we briefly summarize applications of MSI in plant studies. We then turn our discussion to the challenges and developments in quantitative MSI, with a particular focus on ambient liquid extraction-based methods. Quantitative MSI is an emerging discipline in plant studies and holds great promise for revealing new information about the molecular composition of plant tissues and the pathways that regulate plant physiology.