In vitro establishment of nitrogen-fixing strawberry (Fragaria × ananassa) via artificial symbiosis with Azomonas insignis

Summary

Artificial symbiosis was established between diazotrophic Azomonas insignis and strawberry (Fragaria × ananassa). The partnership was created by in vitro techniques through callus induction and organogenesis. Suitable micropropagation [M3=Murashige and Skoog (1962) (MS) basal medium supplemented with 2.5 µM N⁶-benzyladenine (BA), 0.3 µM gibberellic acid (GA₃), 2.2 µM indole-3-butyric acid (IBA), and 3% sucrose] and plant regeneration [R3=MS mineral salts+555 µM myo-inositol, 1.2 µM thiamine HCl, 4.4 µM BA, 0.5 µM IBA, 0.3 µM α-naphthaleneacetic acid (NAA), 0.5 µM 2,4-dichlorophenoxyacetic acid (2,4-D)] media were developed for the test cultivar Fertödi F5. New shoots containing bacteria were rooted, acclimatized, and planted outdoors. The basis of the partnership during the in vitro phase is the bacterial dependence on the plant metabolic activity, using maltose in the medium as carbon and energy source that can be utilized by the plant cells only. The presence of bacteria in the intercellular spaces of the callus tissues and regenerated plants was proved by re-isolation and microscopic techniques. Nitrogenase activity was also detected in the plant tissues.