Evaluation of the Effectiveness of Selected Antibiotics in the Suppression of Agrobacterium from Cowpea (Vigna Unguiculata L. Walp.) Embryo Explants and as Potential Selective Agents in Agrobacterium-Mediated Transformation

The purpose of the study was to provide baseline information on Agrobacterium growth control and suitable selective agent(s) for use in in vitro cowpea genetic transformation studies. Ampicillin was identified as an effective alternative to cefotaxime, in suppressing Agrobacterium tumefaciens. It shows no toxicity to cowpea tissues at a concentration of up to 500 mgl-1. Cefotaxime did not inhibit shoot regeneration or growth but ampicillin is more economical than cefotaxime. This study also examined the effect of four different aminoglycoside antibiotics; geneticin, paromomycin, kanamycin and neomycin, on the regeneration of cowpea decapitated embryos, in an attempt to develop a selection system for in vitro cowpea transformation and regeneration. Plant regeneration was completely inhibited by geneticin (50-500 mgl-1), kanamycin (200-500 mgl-1), paromomycin (400-500 mgl-1) and neomycin at (300-500 mgl-1). Kanamycin (200 mgl-1) and geneticin (10 mgl-1) are suggested as potential agents for selection of transformed cowpea tissues. Key words: Agrobacterium tumefaciens, aminoglycoside antibiotics, genetic transformation and regeneration, Vigna unguiculat