title: Acetosyringone, pH and temperature effects on transient genetic transformation of immature embryos of Brazilian wheat genotypes by Agrobacterium tumefaciens.
abstract: Low transformation efficiency is one of the main limiting factors in the establishment of genetic transformation of wheat via Agrobacterium tumefaciens. To determine more favorable conditions for T-DNA delivery and explant regeneration after infection, this study investigated combinations of acetosyringone concentration and pH variation in the inoculation and co-cultivation media and co-culture temperatures using immature embryos from two Brazilian genotypes (BR 18 Terena and PF 020037). Based on transient expression of uidA, the most favorable conditions for T-DNA delivery were culture media with pH 5.0 and 5.4 combined with co-culture temperatures of 22 °C and 25 °C, and a 400 μM acetosyringone supplement. These conditions resulted in blue foci in 81% of the embryos. Media with more acidic pH also presented reduced A. tumefaciens overgrowth during co-culture, and improved regeneration frequency of the inoculated explants. BR 18 Terena was more susceptible to infection by A. tumefaciens than PF 020037. We found that it is possible to improve T-DNA delivery and explant regeneration by adjusting factors involved in the early stages of A. tumefaciens infection. This can contribute to establishing a stable transformation procedure in the future.
authors.affiliation: Departamento de Plantas de Lavoura, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Ernandes
authors.initials: E
authors.lastname: Manfroi
authors.affiliation: Centro Nacional de Pesquisa em Trigo, Empresa Brasileira de Pesquisa Agropecuária, Passo Fundo, RS, Brazil.
authors.forename: Elene
authors.initials: E
authors.lastname: Yamazaki-Lau
authors.affiliation: Faculdade de Agronomia e Medicina Veterinária, Universidade de Passo Fundo, Passo Fundo, RS, Brazil.
authors.forename: Magali F
authors.initials: MF
authors.lastname: Grando
authors.affiliation: Faculdade de Agronomia e Medicina Veterinária, Universidade de Passo Fundo, Passo Fundo, RS, Brazil.
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Roesler