Applying the pthA effector protein of Xanthomonas citri subsp. citri for production of specific antibodies and its application for detection of infected plants

  • Hamideh Raeisi
  • Mohammad Reza SafarnejadEmail author
  • Seyed Mehdi Alavi
  • Seyed Ali Elahinia
  • Naser Farrokhi
Original Article


Bacterial citrus canker, caused by Xanthomonas citri subsp. citri, is a major disease of citrus throughout the world. The pthA bacterial effector protein, as an essential element for pathogenesis, is present within the infected plants. Here, development of a specific antibody raised against pthA as an early diagnostic tool is reported. For this aim, partial sequence at the C-terminus of pthA gene (606 bp), was PCR-amplified and cloned. The coding region of truncated pthA, t-pthA, was inserted into the pET28a(+) bacterial expression vector. The recombinant t-pthA was expressed in Escherichia coli strain Rosetta (DE3) and purified via affinity chromatography. The purity and integrity of expressed protein was confirmed by SDS-PAGE followed by Western blot analysis using anti-His antibody. The purified recombinant t-pthA was used for immunization of rabbits. Immunoglobulin was purified using protein A Sepharose. The binding ability of prepared IgG was confirmed via a suppression assay performed by direct injection of purified IgG into tobacco leaves followed by infiltration of purified t-pthA protein into leaves. This assay revealed that the presence of anti-pthA IgG prevents hypersensivity response (HR) of t-pthA within the infiltrated leaves. Further in vitro assays such as PTA-ELISA, Dot Immunobinding Assay (DIBA), and Western blot analysis proved the ability of prepared antibody for efficient detection of infected citrus plants. To the best of our knowledge, this is the first report for applying bacterial effector protein, such as pthA, as an antigen for developing a diagnostic approach against a plant bacterial disease.


Citrus bacterial canker Effector protein Recombinant protein Anti-pthA IgG 



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Copyright information

© Società Italiana di Patologia Vegetale (S.I.Pa.V.) 2019

Authors and Affiliations

  1. 1.Department of Plant Protection, College of Agricultural SciencesGuilan UniversityRashtIran
  2. 2.Department of Plant Viruses, Iranian Research Institute of Plant ProtectionAgricultural Research Education and Extension Organization of Iran (AREEO)TehranIran
  3. 3.Department of Plant BiotechnologyNational Institute of Genetic Engineering and BiotechnologyTehranIran
  4. 4.Departement of Cell & Molecular Biology, Faculty of Life Sciences & BiotechnologyShahid Beheshti University G.CTehranIran

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