MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF XANTHOMONAS ORYZAE PV. ORYZAE (ISHIYAMA), THE LEAF BLIGHT PATHOGEN OF RICE (ORYZA SATIVA L)

Abstract

Bacterial blight disease of rice is a serious threat to rice cultivation of India. Xanthomonas oryzae pv. oryzae, (Xoo) the causal organism of bacterial blight disease of rice was isolated from diseased leaf samples and pure cultured on MW medium. The culture was tested for its pathogenicity on 65 days old seedling of a susceptible rice cultivar Taichung Native-1. With the help of SES scoring, the cultivar was found to be highly susceptible to the isolate after 30 days of pathogen inoculation. The culture was microscopically and molecularly identified. Microscopic visualisation of the bacteria through compound microscope at 100X magnification and scanning electron microscope at 9.00K magnification confirmed that bacterial cells appeared in the form of rod shaped measuring each cell size of 1.2 x 0.52 μm. The culture was confirmed as Xoo through molecular identification by using 16S and 23S rDNA gene specific primers. The conserved region of the isolate was amplified and the size was found to be of 470bp in agarose gel electrophoresis The nucleotide sequence obtained was BLAST and was submitted to NCBI. The accession number obtained for Xoo was MZ158566. Motif analysis of closest species with native Xoo was performed and four conserved sequences were obtained among the tested strains.