NARINGENIN ENHANCED EFFICIENCY OF GUS ACTIVITY IN Passiflora mollissima (H.B.K.) Bailey

The flavonoid naringenin has been investigated as a possible vir gene inducer in Agrobacterium-mediated transformation in Passiflora mollissima, P. giberti and Nicotiana tabacum cv. Xanthi. The transformation efficiency percentage of explants showing blue GUS expression and the extent of staining following inoculation with Agrobacterium tumefaciens strains EHA 105 and 1065, carrying gus and nptII genes was enhanced with the supplementation of the co-cultivation medium with naringenin. Supplementation of medium with 100µM (strain EHA 105) and 300 µM (strain 1065) naringenin was most effective at enhancing mean (±s.e.m., n=3) GUS activity in leaf explants (20.3 ± 2.4%, strain EHA; 105; 6.0 ± 0.57%, strain 1065) and nodal segments (16.7 ± 2.4% strain EHA 105; 8.3 ± 0.57% strain 1065) of P. mollissima. In P. giberti and N. tabacum maximum GUS activity was obtained in leaf and root explants with 100µM naringenin for both strains analysed. Additionally, when naringenin was added to Luria Bertani (LB) medium, both bacterial growth via optical density and colony forming units were higher when compared to control. This is the first report of the use of naringenin to enhance gene transfer from Agrobacterium to plants. These findings suggest that naringenin can be used as an alternative to acetosyringone for vir gene induction in Agrobacterium. This approach may be especially useful in plants that are generally recalcitrant to Agrobacterium-mediatedtransformation