Significance of different carbon sources and sterilization methods on callus induction and plant regeneration of Miscanthus x ogiformis Honda `Giganteus'

Abstract

Different carbon sources, sterilized by autoclaving or filter-sterilization, were tested during induction, maintenance, and plant regeneration of embryogenic Miscanthus x ogiformis Honda `Giganteus' callus, derived from various explant types. Explants from small immature inflorescences, between 2.5 and 8 mm, produced more embryogenic callus than explants from shorter or longer inflorescences, shoot apices or leaf explants. On medium containing mannitol or sorbitol, only small amounts of callus were induced and no embryogenic callus was formed. Callus induction and embryogenic callus formation on shoot apices and immature inflorescences did not differ significantly between media containing sucrose, glucose, fructose, maltose or a mixture of glucose and fructose. However, callus induction and embryogenic callus formation from leaf explants were best on glucose. A higher percentage of leaf explants formed callus on autoclaved sucrose, as opposed to the other carbon sources where filter-sterilization in general resulted in a higher callus percentage. The growth rate of embryogenic callus was influenced both by carbon source and sterilization method when less than 1 g of callus was inoculated. None of the tested carbon sources could considerably improve plant regeneration from M. `Giganteus' callus, but a higher number of plants tended to be regenerated per callus piece from filter-sterilized carbon sources.