Agricultural bacterial diseases such as bacterial spot, citrus canker, and Huanglongbing (HLB) are debilitating the industry. HLB is particularly devastating as the disease affects the entire host plant. Antibiotics are presently the leading methodology for systemic treatment of plant systemic bacterial diseases such as HLB disease. The bacteria which causes HLB disease is <i>Candidatus Liberibacter</i> and lives in the phloem of the plant. In addition, in recent years there have been developments towards using systemically targeted nanoengineered pesticides. Detecting if and where these materials localize systemically, and how they translocate through the vascular tissue of the plant is a challenging task due to the absence of methods in the field that can provide direct systemic localization with high resolution.<br/>Here we propose Fluorescence lifetime imaging microscopy (FLIM) as a technique to track suspected systemic pesticides in-planta. Using FLIM, the localization and translocation kinetics of delivered pesticide was determined.  We found that cargo designed with long excited state lifetime properties was easily detected with FLIM throughout the plant even in the presence of significant plant tissue autofluorescence. We found that translocation occurs within just 3 hours of delivery, with full translocation within 24 hours for small molecules. Nanoengineered pesticides were found to translocate much more slowly, or not at all, which we suggest is related to particle size and surface charge. Interestingly, little translocation into the roots was detected even after a week from delivery. In addition, we explored the effect of delivery method on systemic behavior of small molecule and nanoengineered pesticides. Through microneedle roller delivery followed by tree wrap we were able to directly deliver to the phloem.<br/>

Using fluorescence lifetime imaging microscopy for tracking translocation of small molecule pesticides in citrus seedlings

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.