Isolation and characterization of seed-Borne pathogenic bacteria from rice (Oryza sativa L.) in Tanzania

Abstract

A study was conducted to isolate and characterize seed-borne bacterial pathogens from sixty rice (Oryza sativa L.) varieties in Tanzania. Various methods, including the slide cassette holder test, liquid assay and direct plating, were used to isolate bacterial pathogens. The isolated bacterial strains were identified based on colony morphology, biochemical, serological and pathogenicity tests. Acidovorax avenae subsp. avenae, the causal agent of brown stripe was detected in 63% of the seed samples tested indicating that this pathogen is widely distributed in Tanzania. Other pathogens identified were Pantoea agglomerans causing palea brpwning, Xanthomonas oryzae pv. oryzae causing bacterial blight and Burkholderia glumae which causes grain rot of rice. The presence of these seed-borne bacterial pathogens in rice indicates the importance and the need for designing effective control measures of such diseases in order to limit their spread to variou~ rice growing regions in Tanzania where they may not be present.

Keywords: bacteria, disease, Oryza sativa, seed-borne, Acidovorax avenae subs. avenae, Pantoea agglomerans

Tanzania J. Agric. Sc. (1999) Vo. 2 No.1, 71-80