Effect of X-irradiation on Citrus Canker Pathogen Xanthomonas citri subsp. citri of Satsuma Mandarin Fruits

Song, Min-A;Park, Jae Sin;Kim, Ki Deok;Jeun, Yong Chull

  • Received : 2015.06.08
  • Accepted : 2015.08.06
  • Published : 2015.12.01


Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is one of the most important bacterial diseases of citrus. Because citrus canker is not found in many countries including European Union and Australia, Xcc is strictly regulated in order to prevent its spread. In this study, the effects of X-irradiation on Xcc growth either in the suspension or on the surface of citrus fruits were investigated. The suspension containing $1{\times}10^7cfu/ml$ of Xcc was irradiated with different absorbed doses of X-irradiation ranging from 50 to 400 Gy. The results showed that Xcc was fully dead at 400 Gy of X-irradiation. To determine the effect of X-irradiation on quarantine, the Xcc-inoculated citrus fruits were irradiated with different X-ray doses at which Xcc was completely inhibited by an irradiation dose of 250 Gy. The $D_{10}$ value for Xcc on citrus fruits was found to be 97 Gy, indicating the possibility of direct application on citrus quarantine without any side sterilizer. Beside, presence of Xcc on the surface of asymptomatic citrus fruits obtained from citrus canker-infected orchards was noted. It indicated that the exporting citrus fruits need any treatment so that Xcc on the citrus fruits should be completely eliminated. Based on these results, ionizing radiation can be considered as an alternative method of eradicating Xcc for export of citrus fruits.


citrus disease;environment friendly;exportation;radioactivity;sterilization


  1. Abu-Tarboush, H. M., Al-Kahtani, H. A., Atia, M., Abou-Arab, A. A., Bajaber, A. S. and El-Mojaddidi, M. A. 1997. Sensory and microbial quality of chicken as affected by irradiation and postirradiation storage at $4.0^{\circ}C$. J. Food Prot. 60:761-770.
  2. Ahn, H. J., Kim, J. H., Kim, J. K., Kim, D. H., Yook, H. S. and Byun, M. W. 2005. Combined effects of irradiation and modified atmosphere packaging on minimally processed Chinese cabbage (Brassica rapa L.). Food Chem. 89:589-597.
  3. Aquino, K. A. S. 2012. Sterilization by gamma irradiation. In: Gamma Radiation, ed. by A. Feriz, pp. 171-206. InTech Press, Croatia.
  4. Aquino, S., Ferreira, F., Ribeiro, D. H. B., Correa, B., Greiner, R. and Villavicencio, A. L. C. H. 2005. Evaluation of viability of Aspergillus flavus and aflatoxins degradation in irradiated samples of maize. Braz. J. Microbiol. 36:352-356.
  5. Bell, C. H., Price, N. and Chakrabarti, B. 1996. The methyl bromide issue. eds. by Wiley and Sons, Chichester, UK. 400 pp.
  6. Cao, M., Fu, Y., Guo, Y. and Pan, J. 2009. Chlamydomonas (chlorophyceae) colony PCR. Protoplasma 235:107-110.
  7. Coletta-Filho, H. D., Takita, M. A., Souza, A. A., Neto, J. R., Destefano, S. A. L., Hartung, J. S. and Machado, M. A. 2006. Primers based on the rpf gene region provide improved detection of Xanthomonas axonopodis pv. citri in naturally and artificially infected citrus plants. J. Appl. Microbiol. 100:279-285.
  8. Clavero, M. R., Monk, J. D., Beuchat, L. R., Doyle, M. P. and Brackett, R. E. 1994. Inactivation of Escherichia coli O157: H7, Salmonellae, and Campylobacter jejuni in raw ground beef by gamma irradiation. Appl. Environ. Microbiol. 60:2069-2075.
  9. Das, A. K. 2003. Citrus canker-A review. J. Appl. Hort. 5:52-60.
  10. Del Campo, R., Russi, P., Mara, P., Mara, H., Peyrou, M., De Leon, I. P. and Gaggero, C. 2009. Xanthomonas axonopodis pv. citri enters the VBNC state after copper treatment and retains its virulence. FEMS Microbiol. Lett. 298:143-148.
  11. Dezordi, C., Maringoni, A. C., Menten, J. O. M. and Camara, R. C. 2009. Semi-selective culture medium for Xanthomonas axonopodis pv. malvacearum detection in cotton seeds (Gossypium hirsutum L.). Asian J. Plant Pathol. 3:39-49.
  12. Drake, S. and Neven, L. 1997. Quality response of 'Bing' and 'Rainier' sweet cherries to low dose electron beam irradiation. J. Food Process Preserv. 21:345-351.
  13. Elgazzar, A. H. and Kazem, N. 2015. Biological effects of ionizing radiation. In: The pathophysiologic basis of nuclear medicine, ed. by Elgazzar, A. H., pp. 369-370. Springer-Verlag, Berlin, Germany.
  14. Farkas, J. 2006. Irradiation for better foods. Trends Food Sci Technol. 17:148-152.
  15. Fields, P. G. and White, N. D. G. 2002. Alternatives to methyl bromide treatments for stored-product and quarantine insects. Annu. Rev. Entomol. 47:331-359.
  16. Gareau, B. J. 2010. A critical review of the successful CFC phase-out versus the delayed methyl bromide phase-out in the montreal protocol. Int. Environ Agreements Polit Law Econ. 10:209-231.
  17. Golmohammadi, M., Cubero, J., Penalver, J., Quesada, J., Lopez, M. and Llop, P. 2007. Diagnosis of Xanthomonas axonopodis pv. citri, causal agent of citrus canker, in commercial fruits by isolation and PCR-based methods. J. Appl. Microbiol. 103:2309-2315.
  18. Gottwald, T. R., Graham, J. H. and Schubert, T. S. 2002. Citrus canker: The pathogen and its impact. Plant Health Prog. 10:1-34.
  19. Gottwald, T. R., Hughes, G., Graham, J. H., Sun, X. and Riley, T. 2001. The citrus canker epidemic in Florida: the scientific basis of regulatory eradication policy for an invasive species. Phytopathology 91:30-34.
  20. Graham, J. H., Gottwald, T. R., Cubero, J. and Achor, D. S. 2004. Xanthomonas axonopodis pv. citri: Factors affecting successful eradication of citrus canker. Mol. Plant Pathol. 5:1-15.
  21. Grieb, T. A., Forng, R. Y., Stafford, R. E., Lin, J., Almeida, J., Bogdansky, S., Ronholdt, C., Drohan, W. N. and Burgess, W. H. 2005. Effective use of optimized, high-dose (50 kGy) gamma irradiation for pathogen inactivation of human bone allografts. Biomaterial 26:2033-2042.
  22. Hallman, G. J. 2011. Phytosanitary applications of irradiation. Compr. Rev. Food Sci. Food Saf. 10:143-151.
  23. Han, S. H., Jeun, Y. C. and Song, S. J. 2014. Changes of physical character and quality in Satsuma mandarin fruit irradiated by ${\gamma}$- and X-ray during low temperature storage. In: Physiology and Production, The third International Symposium on Citrus Biotechnology, Shizuoka, International Society For Horticultural Science (ISHS), Leuven, Belgium.
  24. Hartung, J. S., Daniel, J. F. and Pruvost, O. P. 1993. Detection of Xanthomonas campestris pv. citri by the polymerase chain reaction method. Appl. Environ. Microbiol. 59:1143-1148.
  25. Jeong, J. Y., Yoon, M. C., Lee, K. Y., Jung, K., Kim, H. J., Park, H. J. and Jeong, R. D. 2014. Effect of the combined treatment with gamma irradiation and sodium dichloroisocyanurate on postharvest Rhizopus soft rot of sweet potato. J. Plant Dis. Prot. 121:243-249.
  26. Jeong, R. D. 2014. Use of ionizing radiation as a phytosanitary treatment for postharvest disease control. J. Radiat Ind. 8:97-104.
  27. Kader, A. A. 1986. Potential applications of ionizing radiation in postharvest handling of fresh fruits and vegetables. Food Technol. 40:117-121.
  28. Kim, J. H. and Yun, S. C. 2014. Effect of gamma irradiation and its convergent treatments on lily leaf blight pathogen, Botrytis elliptica, and the disease development. Res. Plant Dis. 20:71-78 (in Korean).
  29. Kim, K. N., Song, M. A., Han, S. H., Song, S. J. and Jeun, Y. C. 2014. Inactivation of Xanthomonas citri subsp. citri and effect on infection of citrus canker by gamma irradiation. Res. Plant Dis. 20:283-288 (in Korean).
  30. Kositcharoenkul, N., Chatchawankanphanich, O., Bhunchoth, A. and Kositratana, W. 2011. Detection of Xanthomonas citri subsp. citri from field samples using single-tube nested PCR. Plant Pathol. 60:436-442.
  31. Lee, N. Y., Jo, C., Shin, D. H., Kim, W. G. and Byun, M. W. 2006. Effect of ${\gamma}$-irradiation on pathogens inoculated into ready-to-use vegetables. Food Microbiol. 23:649-656.
  32. Mahmoud, G. A., El-Tobgy, K. M. and Abo-El-Seoud, M. 2010. Application of combined biocides and gamma radiation for keeping good quality stored grapefruits. Arch. Phytopathol. Plant Prot. 43:712-721.
  33. Maity, J. P., Kar, S., Banerjee, S., Sudershan, M., Chakraborty, A. and Santra, S. C. 2011. Effects of gamma radiation on fungi infected rice (in vitro). Int. J. Radiat. Biol. 87:1097-1102.
  34. Mayer-Miebach, E., Stahl, M., Eschrig, U., Deniaud, L., Ehlermann, D. and Schuchmann, H. 2005. Inactivation of a non-pathogenic strain of E. coli by ionising radiation. Food Control. 16:701-705.
  35. Mohammadi, M., Mirzaee, M. and Rahimian, H. 2001. Physiological and biochemical characteristics of iranian strains of Xanthomonas axonopodis pv. citri, the causal agent of citrus bacterial canker disease. J. Phytopathol. 149:65-75.
  36. Mostafavi, H. A., Mirmajlessi, S. M., Fathollahi, H., Minassyan, V. and Mirjalili, S. M. 2013. Evaluation of gamma irradiation effect and pseudomonas flourescens against penicillium expansum. Afr. J. Biotechnol. 10:11290-11293.
  37. Niemira, B. A. 2003. Irradiation of fresh and minimally processed fruits, vegetables and juices. In: The microbial safety of minimally processed foods, eds. by John, S. N., Gerald, M. S. and Vijay, K. J, pp. 279-300. CRC Press, Florida, USA.
  38. Osteen, C. 2003. Methyl bromide phaseout proceeds: Users request exemptions. Amber Waves 1:23-27.
  39. Penner, J. E. 1999. Aviation and the global atmosphere. ed. Cambridge University Press, UK. 333 pp.
  40. Schaad, N. W., Postnikova, E., Lacy, G., Sechler, A., Agarkova, I. V. Stromberg, P. E., Stromberg, V. K. and Vidaver, A. K. 2006. Emended classification of xanthomonad pathogens on citrus. Syst. Appl. Microbiol. 29:690-695.
  41. Schubert, T. S., Rizvi, S. A., Sun, X., Gottwald, T. R., Graham, J. H. and Dixon, W. N. 2001. Meeting the challenge of eradicating citrus canker in Florida-Again. Plant Dis. 85:340-356.
  42. Sheu, D. S., Wang, Y. T. and Lee, C. Y. 2000. Rapid detection of polyhydroxyalkanoate-accumulating bacteria isolated from the environment by colony PCR. Microbiology 146:2019-2025.
  43. Sommers, C. H. and Boyd, G. 2006. Variations in the radiation sensitivity of food borne pathogens associated with complex ready-to-eat food products. Radiat Phys. Chem. 75:773-778.
  44. Stall, R. E. and Civerolo, E. L. 1991. Research relating to the recent outbreak of citrus canker in florida*. Annu. Rev. Phytopathol. 29:399-420.
  45. Van Kooij, J., Leveling, H. and Schubert, J. 1978. Food Preservation by Irradiation. Vol. II. IAEA, Vienna, Austria. 63 pp.
  46. Vauterin, L., Hoste, B., Kersters, K. and Swings, J. 1995. Reclassification of Xanthomonas. Int. J. Syst. Bacteriol. 45:472-489.
  47. Watson, R., Albritton, D., Anderson, S. and Lee-Bapty, S. 1992. Methyl bromide: Its atmospheric science, technology, and economics. In: Montreal Protocol Assessment Suplement, United Nations Environment Programme, Nairobi, Kenya. 234 pp.
  48. World Health Organization (WHO). 1981. High dose irradiation. In: Wholesomeness of irradiated food. WHO Technical Report Series 659. Geneva, Switzerland.
  49. Yoon, M. C., Jung, K., Lee, K. Y., Jeong, J. Y., Lee, J. W. and Park, H. J. 2014. Synergistic effect of the combined treatment with gamma irradiation and sodium dichloroisocyanurate to control gray mold (Botrytis cinerea) on paprika. Radiat Phys. Chem. 98:103-108.
  50. Youssef, B. 1994. Microbial flora of frozen beef burger as affected by gamma radiation. Egypt. J. Microbiol. 29:105-113.


Supported by : Ministry of Agriculture, Food and Rural Affairs