Abstract

The causal agents of bacterial blight in lupine (Lupinis termis) were isolated from leaves displaying symptoms in Minia governorate, Egypt. The pathogens were characterized by biochemical and physiological tests, and identified as Bacillus megaterium. Tissue extracts prepared from experimentally diseased shoot systems showed great pectolytic and cellulolytic activities while healthy tissue extracts of both organs showed slight activities of the enzymes. In varietal response test, four lupine cultivars that is, Australian, Balady, Giza 1 and Giza 2 were tested for their susceptibility to all tested B. megaterium isolates and the cultivar Balady was most sensitive to all isolates. However, isolates B2 and B6 were more virulent than the others. Two isolates of B. megaterium isolates that caused blight on lupine plants were subsequently tested on other foliar plants representatives of 17 plant species. Both B. megaterium isolates could not infect any of the tested plants but produced small necrotic spots on faba bean leaves. These results indicate the host specificity of this bacterium towards its host plant and accordingly justify the suggested forma specials lupini to be given to the lupine bacterial pathogen B. megaterium. According to the literature review, this is the first report on the occurrence of B. megaterium as a causal agent of leaf blight of lupine plants in Egypt.

Key words: Bacillus megaterium, lupine, pectolytic and cellulolytic activities, cultivars.