Translocation of Oxytetracycline in Citrus Plants after Root Drench and Stem Delivery
Date
2020-07-03
Authors
Killiny, Nabil
Hijaz, Faraj
Al-Rimawi, Fuad
Nehela, Yasser
Batuman, Ozgur
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Abstract
Huanglongbing (HLB) is the most destructive disease to the citrus industry. In North America, HLB is caused by Candidatus
Liberibacter asiaticus (CLas) and is transmitted by the Asian citrus psyllid, Diaphorina citri. Recent studies
showed that antibiotics such as oxytetracycline and streptomycin were effective against the CLas pathogen in planta.
The objectives of this study were to investigate the uptake, translocation, and stability of oxytetracycline in citrus
seedlings. Oxytetracycline was delivered via root or stem. The level of oxytetracycline in treated plants was monitored
using high-performance liquid chromatography (HPLC) and/or enzyme-linked immunosorbent assay (ELISA). The
HPLC and the ELISA methods showed similar results at high concentrations; however, the ELISA was more sensitive
than the HPLC method. The highest level of oxytetracycline after root incubation was found in roots, followed by
stem-xylem, stem-phloem, and in leaves. On the other hand, the level of oxytetracycline in the xylem and phloem was
higher than that found in the root when delivered via stem. Oxytetracycline was still detectable in all tested tissues
thirty-five days after treatment, indicating that oxytetracycline was relatively stable in citrus plants and could inhibit
CLas growth for a few months in the field.