1. Please state project objectives and what work was done this quarter to address them:
Objective 1: Using callose inhibitors to improve systemic uptake and reduce HLB symptoms.
leaf sample collection of 5-month (March 4th 2024) after 4 treatments : (1) injected control (water), (2) Oxytetracycline (2 g per tree), (3) DDG (0.1mM) + Oxytetracycline (2 g per tree), (4) 3AB (0.1mM) + Oxytetracycline (2 g per tree).
because of the lack of watering in 2023 and 2024 (Pretreatment, 10-day, 1-month, 3-month and 5-month after treatments), we restarted the field trial of trunk injection on a healthier group of 72 sweet orange (around 8-10 years old) trees. Here, we focused on the 3AB callose inhibitor and Oxytetracycline (OTC) according to 6 different treatments: (1) injected control (water), (2) OTC (2 g per tree), (3) 3AB (1mM), (4) 3AB (1mM)+ OTC (2 g per tree), (5) 3AB (10mM), (6) 3AB (10mM)+ OTC (2 g per tree). Before applying treatments, baseline stomatal conductance data and data related to trunk diameter, canopy volume and canopy density was collected, and CLas titer and quantify callose level of each tree were measured in May 1st 2024. The trunk injection was employed in May 2nd 2024. Following to the scheduled dates, we collected six mature leaf samples per tree to measure the CLas titer and quantify callose level of each tree 15-day (May 17th 2024) after treatments.
Objective 2: Maintaining water-saturated injection site: Sealed trunk injection ports that stay functional by avoiding wound
responses.
Field experiments for this objective have been completed. None of the approaches tested resulted in continued uptake beyond two days after injection. Injury responses appear to trump water-saturation in xylem occlusion.
Objective 3: Targeted root delivery.
Experiment began in January and roots were harvested in May. Data analysis is ongoing. Observations look promising.
2. Please state what work is anticipated for next quarter:
The following scheduled dates of leaf sample collection will start monthly from June 3rd 2024 (1-month after treatments) to August 2nd 2024 (3-month after treatments). We will evaluate the trees for callose level and CLas titre to measure the effect of the callose inhibitor (3AB) with different concentrations on trees, compared to control treatment.
3. Please state budget status (underspend or overspend, and why):
Underspend- we are having problems to initiate the work proparly.
4. Please show all potential commercialization products resulting from this research, and the status of each:
We are still evaluating the effect of the callose inhibitor in the field trials