Maize elite inbred lines are susceptible to Agrobacterium tumefaciens-mediated transformation

Eleven maize inbred lines were employed as target genotypes for Agrobacteri um-mediated transformation. Six Agrobacterium strains, characterized by dif ferent chromosomal background and Ti-plasmid content, were chosen for infec tion of immature embryos and embryogenic primary calli; transformation effi ciency was detected via histochemical staining for B-glucuronidase expressi on. In all cases, the addition of acetosyringone, as an elicitor of vir gen es, was employed. Microbombardment of the scutellar tissues was also tested as treatment mimicking a wounding response of the embryogenically competen t cells. The efficiency of transformation was evaluated for each inbred, co nsidering the interaction among maize genotypes and Agrobacterium strains. With the exception of inbred Lo 1123, in all cases a proper combination Agr obacterium strain/maize genotype was found, giving a histochemical positive response for GUS assay. The most effective Agrobacterium strains were C58 and EHA101. Additionally, two inbred lines, A188 and Lo1054, were evaluated for transformation using embryos at different maturation stages. The resul ts obtained support the possibility of identifying an optimal embryo stage for the induction of embryogenic callus and for Agrobacterium infection. Th is would be helpful to establish desirable experimental conditions needed f or stable transformation of a given maize genotype.