Effect of inoculation time on <i>Agrobacterium</i>-mediated transformation efficiency of <i>Musa</i> cv. ‘Grande naine’ (AAA)

Abstract

Increasing inoculation time during Agrobacterium-mediated transformation has been shown to favour transformation efficiency in several plant species. The effect of inoculation time in combination with spermidine (Spd) on efficiency was determined during Agrobaterium-mediated transformation of the Musa cultivar ‘Grande naine’ (AAA). Banana embryogenic cell suspensions (ECSs) were incubated with the bacterial strain EHA 105 carrying the binary vector pFAJ3000. Six different inoculation conditions (6 h, 6 h+Spd, 12 h, 12 h+Spd, 24 h, 24 h+Spd) were compared based on transient GUS expression and number of embryo colonies formed. Moreover, leaf fragments from 24 randomly chosen regenerated plantlets were assayed presence and expression of the transgenes. Consequently, samples that were inoculated for 24 h in medium supplemented with 1 mM spermidine showed the highest transformation efficiency, expressed as number of blue foci and regenerated colonies after the selection treatment. Here we showed for the first time that longer inoculation times in combination with spermidine enhance the efficiency of Agrobacterium-mediated transformation of the banana cultivar ‘Grande naine’. Keywords: banana, β-glucuronidase, genotype, somatic embryo, PCR