Isolation and Identification of Xathomonas Oryzae PV. Oryzae the Causal Agent of Bacterial Blight of Rice in Iran
2008
Ghasemie, Elham | Kazempour, Mostafa | Padasht, Ferydon
Bacterial blight caused by Xanthomonas oryzae pv. oryzae is one of the important bacterial diseases on rice. This disease causes typical symptoms on infected rice such as leaf blight which appears on leaves of young plants, after planting out, as pale-green to grey-green water-soaked streaks near the leaf tip and margins. In this research, during the period from 2004 to 2005, samples of infected plant were collected from different areas of Guilan province (Rasht, Lahijan, Foman, Anzaly, Talesh, Roudsarm Roudbar and Astara), to identify the causal agent of disease. For isolation of bacteria, infected tissue of leaves, stems and roots were crushed in pepton water then 100 μl of homogenate were cultured on nutrient agar (NA) and yeast dextrose carbonate (YDC) containing cyclohexamid antibiotic (50 μg/ml). Isolates of bacteria rod-shaped, gram negative bacteria and aerobic bacterium were obtained. The former isolates produced levan on media including sucrose. All isolates induced hypersensitive reaction (HR) on tobacco and geranium leaves. All of the isolated bacteria were oxidase, nitrate, urease, Tween 80 hydrolysis and indole negative and could not produce rot on potato tuber slices, produced H₂S and grew in 36°C. The isolates could use citrate, L-lysin and cystein. The isolates produced acid from arabinose, galactose, myo-inositol, fruoctose, trehalose and mannose and hydrolyzed gelatin. Based on morphological, physiological, biochemical tests, PCR method with specific primers and pathogenicity properties, the predominant pathogenic type was identified as X. oryzae pv. oryzae. To the best of our knowledge, this is the first record of bacterial blight of rice in Iran.
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