Rapid Molecular Detection and Transmission of Bacterial Leaf Streak Pathogen, Xanthomonas Oryzae Pv. Oryzicola, in Rice Seeds

Mark Paul Rivarez^1,2,* and Elizabeth Parac³

¹College of Agriculture and Food Science, University of the Philippines, Laguna, Philippines.

²Present Address: Department of Biotechnology and Systems Biology, National Institute of Biology and, Jožef Stefan International Postgraduate School, Ljubljana, Slovenia.

³College of Agriculture and Agri-Industries, Caraga State University, Butuan City, Philippines.

Corresponding Author E-mail: msrivarez@up.edu.ph

DOI : http://dx.doi.org/10.13005/bbra/2765

ABSTRACT: Xanthomonas oryzae pv. oryzicola (Xoc) is a seed-borne bacterial pathogen of rice. In this study, a rapid molecular detection method in seeds was developed to prevent unwanted movement of infected materials and greater yield loss. Crude DNA from ground seed extract supernatant was precipitated in ethanol and centrifuged. DNA pellets of homogenous subsamples were pooled and werepurified using SDS or a DNA extraction kit. Three pairs of primers previously designed on Xoc isolate BLS-256 genome sequence robustly amplify Xoc-specific DNA sequences. Primer T40 was found to efficiently detect Xoc but only in single primer reactions. While primers 3864 and 3866 can amplify Xoc DNA separately, however, their multiplex PCR reactions were unsuccessful, probably due to substrate competition in the reaction mixture. Optimized PCR mixture and conditions were able to detect as low as 10 cfu/mL Xoc cells and the direct extraction method and conditions were able to detect as low as 10⁴ cfu/mL inoculated cells using primer T40. Lastly, Xoc transmission through seeds was observed only in plant samples which were heavily infected. Recovery from infection, at around 25-50% was also observed in some cultivars which also manifested good grain filling at 56 days after transplanting.

KEYWORDS: Molecular Diagnostics; Rice Seeds; Seed-Borne Pathogens; Xanthomonas; Xoc

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