In vitro rooting of araucaria excelsa R. Br. var. glauca using Agrobacterium rhizogenes

Abstract

The family Araucariaceae encompasses several evergreen forest tree species, which has a high ornamental value due to being a good specimen and having symmetrical branches. Conventional propagation of Araucaria excelsa R. Br. var. glauca by cutting has limited success because of topophysis and difficult-to-root characteristics, and grafting is accompanying incompatibility. The aim of this research was to evaluate the application of Agrobacterium rhizogenes as well as the IBA, NAA and ancillary compounds potential to increase the rooting of this plant under in vitro condition. Neither ancillary compounds such as salicylic acid, putrescine nor hydrogen peroxide affected the rooting of this recalcitrant species. Subculturing in vitro shoots to MS medium containing 7.5 μM of both IBA and NAA for 15 days before being moved to hormone-free half-strength MS medium, resulted in a 33% increase of rooting of shoots each with one or two roots. Using Agrobacterium rhizogenes strain K599 improved rooting percentage up to 40%. Green fluorescents protein (GFP) gene, as a reporter gene, was employed to verify the successful transformation.