Iron supplementation promotes in vitro shoot induction and multiplication of Baptisia australis

A simple and efficient system was developed for the rapid in vitro multiplication of Baptisia australis using nodal explants derived from axenic cultures. Among the four cytokinins [benzylaminopurine (BA), kinetin, N6-(2-isopentenyl)adenine (2-iP) and zeatin] tested for axillary bud induction, BA at 4.4 µM proved to be the most effective treatment for induction of multiple shoots from nodal explants after six weeks. Supplementation of Murashige and Skoog (MS) and Driver and Kuniyuki walnut (DKW) media with a chelated iron source, ethylenediamine Bis (2-hydroxyphenylacetic acid) (FeEDDHA) and BA had a favorable effect on axillary bud proliferation from explants (apical buds and nodal segments) further improving the regeneration response as well as number of shoots induced. DKW media proved to be superior to MS for multiple shoot induction of B. australis. A combination of 4.4 µM BA and 23 µM of FeEDDHA in DKW produced a positive response resulting in 100% of nodal segments responding and regenerating 7.2 shoots per explant. The highest rooting percentage was observed on MS media containing 1 µM IBA. In vitro-rooted plants were successfully acclimated in a greenhouse with a survival rate of 97%. The micropropagation method described in this study has a potential for commercial multiplication of this horticultural plant.