Factors affecting direct organogenesis from flower explants of Allium giganteum

Abstract

A novel method is described for the propagation of Allium giganteum Regel using direct organogenesis resulting in multiple shoot structures formed on mature flower buds or ovaries. A two step induction and differentiation procedure, similar to that described earlier in onion, was tested. Flowers were inoculated on the induction medium for 6 days and extracted ovaries were placed on the differentiation medium. Optimal formation of multiple shoot structures was obtained using modified BDS medium containing 50 g l−1 sucrose solidified by a mixture of agar/gellan-gum, with 8.88 μM benzylaminopurine (BA) and 9.05 μM 2,4 dichlorophenoxyacetic acid (2,4-D) in induction medium and 9.08 μM tidiazuron (TDZ) in the differentiation medium. Five plant sources obtained from different European retailers of ornamental bulbs were tested separately. All tested genotypes produced multiple organogenic structures, although induction percentages clustered in two distinctive groups. Shoots formed tended to become dormant, and attempts to improve their growth and rooting included treatment with fluridone. Dormancy was partly broken when shoots were briefly dipped in 1 μM fluridone. Genetic analysis of plant sources using random amplified polymorphic DNA method showed that 5 retailers actually distribute only two different clones, one of them more and the other less responsive to shoot organogensis.