Somatic embryogenesis of tulip

Abstract

Because the natural propagation rate of tulip is low, modern breeding requires a rapid in vitro propagation method. The best method available at the moment, adventitious shoot formation on stem explants, has a low propagation factor and is laborious, time-consuming and hence expensive. It is the long term aim of the present study to develop a propagation method, consisting of a cell suspension phase, and a regeneration phase, during which the cell clusters regenerate through somatic embryogenesis. A system like this would enable the rapid production of large numbers of bulblets at low costs. In order to obtain friable callus for the start of a cell suspension, bulb scale and stem explants were cultured on a nutrient medium containing the auxins 2,4-D or Picloram at a concentration range from 0.5-50 μM. Undifferentiated and 'meristematic' type of callus on bulb scale explants an were induced. The meristematic type seemed the most suitable to start a liquid culture. In liquid medium the meristematic nodules divided into smaller units, which could be released from the explant by shaking. On stem explants on medium with 5 or 50 μM 2,4-D or Picloram somatic embryos were formed. Morphological and anatomical data on the development of these somatic embryos are presented. The ability to produce somatic embryos offers us the opportunity to use embryo-tissue for the production of embryogenic callus.