Bacterial blight - Xanthomonas oryzae pv. oryzae

EEffective: August 18, 2010 - August 10, 2011
Resources: Pest Tracker CAPS Pest Datasheet
Screening Aids:
Taxonomic Position: Xanthomonadales : Xanthomonadaceae
Pest Type: Bacteria
Pest Code (NAPIS): FBZAXBM
No manual – See Host Matrix
These Approved Methods are appropriate for:
Major Hosts identified in the Host Matrix:
Rice

This list includes important economic or environmental hosts but does not represent all major hosts of the pest. Check CAPS pest datasheet for complete list of hosts.
Pest is vectored by:
No known vector.
Survey
Approved Method(s):
Method Instructions NAPIS Survey Method
Visual Collect symptomatic leaf samples. For a preliminary indications of seed infection, look for bacterial streaming (Singh and Rao, 1977) 3031 - General Visual Observation
Signs:
Amber colored bacterial exudates on surface of lesions with bacterial leaf streak. Bacteria "ooze" out of water pores on hydathodes with bacterial blight.
Symptoms:
Bacterial blight (X. oryzae pv. oryzae) appears on leaves of young plants, after planting out, as pale-green to gray-green and water-soaked streaks near the leaf tip and margins. These lesions coalesce and become yellowish-white with wavy edges. Lesions become dry and wilted (a symptom known as "kresek").

Bacterial leaf streak (X. oryzae pv. oryzicola) is seen as narrow, dark-greenish, water-soaked, interveinal streaks of various lengths on the leaf blades. The lesions enlarge and turn yellow orange to brown and coalesce. The lesions then turn grayish white and die.

Seed may be discolored and poorly filled with bacterial blight. There are no symptoms on seeds with bacterial leaf streak.
Key Diagnostics


ID/Diagnostic: Multiple

Morphological: Colony morphology: The pathogen is difficult to isolate directly from seed due to slow growth of bacterium and overgrowth by other organisms. Jones et al. (1989) describe a new culture medium for culturing X. oryzae pv. oryzae from rice seed. Yuan (1990) developed a semi-selective medium, called XOS, to isolate both pathovars from rice seed. Gnanamanickam et al. (1994) tested three strains for growth on TZC, WF-P, YCM, YAT, MXO, and XOS semi-selective media. Results varied for each isolate used, but worked best when using monoclonal antibodies to confirm the genus and pathovar. Serological: Monoclonal antibodies: Genus and pathovar specific antibodies can be used in an ELISA reaction (Alvarez et al., 1985; Benedict et al., 1989.
Mistaken Identities:
In the early stage of disease, the symptoms are similar to narrow brown leaf spot. At the later stage, when the streaks have coalesced, symptoms of bacterial blight and bacterial leaf streak are similar. The shape of the edges of the lesions differs; straight in leaf streak and wavy in leaf blight. X. oryzae pv. oryzicola may be distinguished from X. oryzae pv. oryzae by colony morphology in typical isolates, strong starch and gelatin hydrolysis, and by biochemical and molecular methods.
In Progress / Literature-based Diagnostics:
Molecular:

PCR/BIO-PCR: Vera Cruz et al. (1995) and Vera Cruz et al. (1996) compared Rep-PCR using repetitive DNA sequences with RFLPS.

Leach et al. (1990) used a repetitive DNA sequence (pJEL101) to distinguish X. oryzae pv. oryzae from other pathovars and species of Xanthomonas.

PCR assays using primers that amplify internal fragments IS 1112 and IS 1113 of X. oryzae pv. oryzae (Cottyn et al., 1994; et al., 1997) have been used as well.

Sakthivel et al.. (2001) developed a PCR technique to detect X. oryzae pv. oryzae in rice seed. A combined biological and enzymatic amplification (BIO-PCR) technique was used to detect the pathogen in naturally infected seed.

Kang et al.. (2008) developed a specific PCR detection system (targets a membrane fusion protein gene) for X. oryzae pv. oryzicola.

Real-time PCR: Zhao et al.. (2007) developed a real-time PCR to detect X. oryzae pv. oryzae and can distinguish it from X. oryzae pv. oryzicola.

Liao et al. (2003) developed a real-time PCR that can distinguish the two pathovars.

Computational Genomics/Multiplex PCR: Lang et al. (2010) used a computational genomics pipeline to compare sequenced genomes of Xanthomonas species to identify regions for development of highly specific diagnostic markers. A suite of primers were selected to monitor diverse loci and to distinguish the rice bacterial blight and leaf streak pathogens. A subset of primers were combined into a multiplex PCR to accurately distinguish the two rice pathogens in a geographically diverse collection from other xanthomonads and other plant pathogenic and plant-or seed associated bacteria.
Notes:
There are two pathovars of X. oryzae pathovar oryzae causes bacterial blight while pathovar oryzicola causes bacterial leaf streak.
X. oryzae pv. oryzae was detected in Louisiana and Texas. Strains were of low virulence compared to Asian strains (Jones et al., 1989)

Discussion with the authors indicates that this find should be a new pathovar and has not been found since they have stopped planting susceptible hosts.

Xanthomonas oryzae is on the Select Agent List.
References
  1. Alvarez, A.M., Benedict, A.A., and Mizumoto, C.Y. 1985. Identification of xanthomonads and grouping of strains of Xanthomonas campestris pv. campestris with monoclonal antibodies. Phytopathology 75: 722-728.
  2. Alvarez, A.M., Rehman, F.U., and Leach, J.E. 1997. Comparison of serological and molecular methods for detection of Xanthomonas oryzae pv. oryzae in rice seed. In: Seed Health Testing: Progress Towards the 21st Century. J.D. Hutchins and J.C. Reeves (eds.). pp. 175-183.
  3. Benedict, A.A., Alvarez, A.M., Berestecky, J., Imanaka, W., Mizumoto, C.Y., Pollard, L.W., Mew, T.W., and Gonzalez, C.F. 1989. Pathovar-specific monoclonal antibodies for Xanthomonas campestris pv. oryzae and for Xanthomonas campestris pv. oryzicola. Phytopathology 79: 322-328.
  4. Cottyn, B., Bautista, A.T., Nelson, R.J., Leach, J.E., Swings, J., and Mew, T.W. 1994. Polymerase chain reaction amplification of DNA from bacterial populations of rice using specific oligonucleotide primers. International Rice Research Note 19: 30-32.
  5. Gnanamanickam, S.S., Shigaki, T., Medalla, E.S., Mew, T.W., and Alvarez, A.M. 1994. Problems in detection of Xanthomonas oryzae pv. oryzae in rice seed and potential for improvement using monoclonal antibodies. Plant Disease 78: 173-178.
  6. Jones, R.K., Barnes, L.W., Gonzalez, C.F., Leach, J.E., Alvarez, A.M., and Benedict, A.A. 1989. Identification of low-virulence strains of Xanthomonas campestris pv. oryzae in the United States. Phytopathology 79(9): 984-990.
  7. Kang, M.J., Shim, J.K., Cho, M.S., Seol, Y.J., Hahn, J.H., Hwang, D.J., and Park, D.S. 2008. Specific detection of Xanthomonas oryzae pv. oryzicola in infected rice plant by use of PCR assay targeting a membrane fusion protein gene. J. Microbiol. Biotechnol. 18(9): 1492-1495.
  8. Lang, J.M., Hamilton, J.P., Diaz, M.G.Z., Van Sluys, M.A., Burgos, M.R.G., Vera Cruz, C.M., Buell, C.R. Tisserat, N.A., and Leach, J.E. 2010. Genomics-based diagnostic marker development for Xanthomonas oryzae pv. oryzae and X. oryzae pv. oryzicola. Plant Disease 94: 311-319.
  9. Leach, J.F., White, F.F., Rhoads, M.L., and Leung, H. 1990. Repetitive DNA sequence differentiates Xanthomonas campestris pv. oryzae from other pathovars of X. campestris. Molecular Plant-Microbe Interactions 3(4): 238-246.
  10. Liao, X., Zhu, S., Zhao, W., Luo, K., and Qi, Y. 2003. Detection and identification of Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola by real-time fluorescent PCR. Wei Sheng Wu Xue Bao 43(5): 626-634. English Abstr.
  11. Ming, D., Ye, H.Z., Schaad, N.W., and Roth, D.A. 1991. Selective recovery of Xanthomonas spp. from rice seed. Phytopathology 81(11): 1358-1363.
  12. Sakthivel, N., Mortensen, C.N., and Mathur, S.B. 2001. Detection of Xanthomonas oryzae pv. oryzae in artificially inoculated and naturally infected rice seeds and plants by molecular techniques. Appl. Microbiol. Biotechnol. 56: 435-441.
  13. Singh, R.A., and Rao, M.H.S. 1977. A simple technique for detecting Xanthomonas oryzae in rice seeds. Seed Science and Technology 5: 123-127.
  14. Vera Cruz, C.M., Ardales, E.Y., Skinner, D.Z., Talag, J., Nelson, R.J., Louws, F.J., Leung, H., Mew, T.W., and Leach, J.E. 1996. Measurement of haplotype variation in Xanthomonas oryzae pv. oryzae within a single field by Rep-PCR and RFLP analyses. Phytopathology 86: 1352-1359.
  15. Vera Cruz, C.M., Halda-Alija, L., Louws, F.J., Skinner, D.Z., George, M.L., Nelson, R.J., de Bruijn, F.J., Rice, C.W., and Leach, J.E. 1995. Repetitive sequence-based polymerase chain reaction of Xanthomonas oryzae pv. oryzae and Pseudomonas species. International Rice Research Note 20: 23-24.
  16. Yuan, W.Q. 1990. Culture medium for Xanthomonas campestris pv. oryzae. Journal of Applied Bacteriology 69: 798-805.
  17. Zhao, W.J., Zhu, S.F., Liao, X.L., Chen, H.Y., and Tan, T.W. 2007. Detection of Xanthomonas oryzae pv. oryzae in seeds using a specific Taqman probe. Molecular Biotechnology 36: 119-127.