Effectiveness of sonication on diminishing bacterial overgrowth in Agrobacterium-mediated transformation

This study was carried out to trace the biological effects of exposing Agrobacterium tumefaciens and sugarcane cell clumps of suspension culture to ultrasonic waves. A diluted suspension of Agrobacterium tumefaciens, strains EHA101 and LBA4404, was treated with 44 kHz sonication which remarkably reduced the frequency of colony formation in the inoculated medium of both strains. The cell clumps of the suspension culture were co- cultured with Agrobacterium, and then sonicated. Following 3 days repeating co- culture in solid medium, the cell clumps were transferred to the MS-1e medium. Without sonication treatment, 31% of cell clumps revealed bacterial overgrowth, whereas no overgrowth was found in the sonication treatment after 14 days of culture. However, no significant differences in the rates of growth and shoot regeneration between the sonication - treated cell clumps and the untreated cell clumps.