Active Fluorescence Plant Activator N-FBT: A New Tool for the Study of Defense Signaling Pathway in Plants

Traditional methods for mechanism studies such as immunoassays and immunocytochemical analysis are comparatively expensive and time-consuming and cannot analyze the targets in a living sample directly. In this paper, we developed a new fluorescence-active compound as a tool to directly study the defense signaling pathway of plant activators in plants. At first, with the active and commercial plant activators FBT and BTH as the starting materials, the two new active fluorescence plant activators N-FBT and N-BTH were designed and synthesized; the second, based on a system for the study of protein-protein interactions, a new nucleolus-tethering system (New-NoTS) especially for the study of interaction between small molecules and proteins was developed. With these two new tools, a series of studies for the defense signaling pathway of new plant activators was conducted. The results showed that N-FBT could interact with both SABP2 (SA pathway) and MYC2 (JA pathway) at the same time while N-BTH only interacted with SABP2. This means that FBT can induce the plant immune system by activating both SA and JA signaling pathways, which directly supported the extensive activities of FBT not only for disease but also for insects. On the other hand, with this method, the interactions between fluorescent plant activators and proteins could be studied directly by visualization.