A rapid and efficient in vitro shoot regeneration protocol using cotyledons of London plane tree (Platanus acerifolia Willd.)

Abstract

A rapid, prolific and reproducible protocol for in vitro shoot regeneration from mature cotyledons of Platanus acerifolia has been developed. The influences of different plant growth regulator (PGR) combinations and donor seedling ages on shoot regeneration were investigated. The results showed that the application of BA in conjunction with NAA was the most effective PGR combination for the induction of shoot regeneration. When cotyledon explants of 5-day-old seedlings were incubated on MS basal medium supplemented with 4.0 mg L−1 BA and 0.2 mg L−1 NAA, 67.6 ± 4.9% of the cotyledon segments produced adventitious shoots. These regenerated shoots were initially formed as stunted rosette cluster forms and were encouraged to elongate to produce distinct shoots by transfer onto MS medium containing 0.5 mg L−1 BA and 0.05 mg L−1 NAA; the resulting mean number of adventitious shoots per explant was 5.81 ± 0.36. The elongated shoots were readily induced to root (i.e. 89.3% of shoots) by incubation on ½-strength MS medium supplemented with 0.1 mg L−1 IBA. This is the first report of an efficient in vitro shoot regeneration protocol for P. acerifolia through direct organogenesis using cotyledon explants. Hence, this provides a more efficient basis for the Agrobacterium-mediated genetic transformation of Platanus than previously available.