In Situ Dynamic Molecular Monitoring of Single Seed Exudates by Induced Electrospray Ionization Mass Spectrometry

Seed exudates are essential for seed germination and shaping the microbiome. However, analyzing single seed exudates in situ is challenging due to their low volume and complexity. This study utilized tapered glass capillary emitters as miniature Petri dishes as well as induced electrospray ionization mass spectrometry (iESI-MS) for in situ collection and real-time analysis of single seed exudates. Through this innovative platform, we observed dynamic changes in amino acids (AAs) and organic acids (OAs) in the central carbon metabolism pathway of single Arabidopsis seed exudates during the imbibition process. Quantitative results revealed that the levels of AAs and OAs exhibited a pattern of an initial increase followed by a decrease. Furthermore, the onset and peak levels of AAs occurred earlier than those of OAs, suggesting that the seeds may adopt a two-step defense mechanism to regulate the composition of the microbiome. This study provides a valuable tool for gaining insight into seed exudates and microbiome interactions.