Chemical Imaging Reveals Diverse Functions of Tricarboxylic Acid Metabolites in Root Growth and Development

Abstract: Understanding how plants grow is critical for agriculture and fundamental for illuminating principles of multicellular development. Here, we apply chemical mapping of the developing maize root using desorption electrospray ionization mass spectrometry imaging (DESI-MSI). This technique reveals a range of small molecule distribution patterns across the gradient of stem cell differentiation in the root. To understand the developmental logic of these patterns, we examined tricarboxylic acid (TCA) cycle metabolites. In both Arabidopsis and maize, TCA metabolites are enriched in developmentally opposing regions, suggesting that stem-cell specific TCA metabolite localization may be conserved in evolutionarily divergent species. We find that these metabolites, particularly succinate, aconitate, citrate, and α-ketoglutarate, control root development in diverse and distinct ways. Critically, the effects of metabolites on stem cell behavior can be independent of their canonical role in ATP production. These results present new insights into development and suggest practical means for controlling plant growth.