Huanglongbing (HLB), more commonly known as citrus greening disease (CGD), is an insect-borne bacterial disease affecting citrus crops worldwide [1]. CGD symptoms can be visually seen throughout the plant, displaying yellowing veins, asymmetrical chlorosis and blotchy leaves, leading to underdeveloped fruit with green colored and stained seeds [1]. The mottling discoloration has been linked to zinc deficiency in the plant, thus monitoring varying concentrations of zinc ions in plants (in particular the phloem tissue) as well as the intake of zinc ions through roots and leaves could help in the understanding of disease progression and possibly therapy [2]. Here, the use of solid contact micro-ion selective electrodes (m-ISEs), equipped with a m-Ag/AgCl reference electrode will provide a method for monitoring free zinc content in the phloem of plants and zinc ions intake in plants in-situ. First, the development, optimization and characterization of the µ-ISE was performed. Figures of merit are calibration curves, selectivity, stability and reproducibility of the sensor. Preliminary studies have yielded a near Nernstian slope of around 26.0 mV response with a limit of detection (LOD) of around 5x10-7 M for zinc ions. The µ-ISE was also used to monitor the intake of zinc ions over time via surface micro profile (MIFE) of a zinc solution. Here, MIFE offers a non-destructive, high spatial and temporal resolution method to quantify the uptake of zinc by the plant through ion flux calculations. For the first-time a (m-ISE) shows promise for application of in situ plant analysis.

A potentiometric solid contact micro-sensor to monitor intake of zinc ions in plants

255th National Meeting (2018)

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