In vitro tetraploid induction and generation of tetraploids from mixoploids in Dioscorea zingiberensis

This article describes an efficient colchicine-mediated technique for the in vitro induction of tetraploids in Dioscorea zingiberensis and its confirmation by flow cytometry. Buds immersed in 0.2% colchicine solution for 36 hours prior to culture induced as high as 35.6% tetraploid plants. Colchicine-induced tetraploids remained stable after six months in soil. Leaf characteristics of diploids and tetraploids in D. zingiberensis were compared. It was determined that the leaf sizes of glasshouse-grown plants and stomatal sizes of both in vitro and glasshouse-grown plants were suitable parameters for identifying putative tetraploids in D. zingiberensis. Besides generating tetraploids, this technique generated mixoploids in D. zingiberensis. Calli derived from mixoploid leaves were induced to form buds and shoots. Individual shoots were classed as diploid, mixoploid, and tetraploid by flow cytometry. This callus-based technique could be employed when a genome-doubling agent generated mixoploids, but no tetraploids.