Production of adventitious embryoids in vitro from stem callus of Foeniculum vulgare

Abstract

In the last few years considerable interest has been shown in the differentiation of embryoids and buds in vitro. However, in spite of many attempts there are only a few reports of organisation in calli originating from stem. Examplewise, one might mention the investi gations on tobacco pith tissue (Skoog and Miller, 1957), potato tubers (Wurm, 1960) parsley petiole (Vasil et al., 1964) and the petiole and umbellet peduncle of carrot (Halperin and Wetherell, 1964). The present report is concerned with the formation of embryoids in a callus obtained from the stem of Foeniculum vulgare Mill. After sterilisation with chlorine water, segments of the stem were inoculated on White's basal medium (White, 1943). Proliferations occurred from the cells of upper cortical region (Fig. la). These were capable of continuous growth on Nitsch's basal medium (Nitsch, 1951) supplemented with coconut milk (CM) and produced a friable yellow callus (Fig. lb). No differentiation was observed even after ten months. However, when the callus was transferred to a fresh medium (Nitsch's basal or Nitsch's basal + coconut milk) it exhibited a differentiation of not only roots but also embryoids in about three weeks. The embryoids developed into buds having two or three leaf primordia. After four to five weeks, green leafy shoots measuring about 1—2 cm in length could be seen. Besides the coconut milk medium, the callus was also subcul tured on Nitsch's basal medium (NB) fortified with /3-indoleacetic acid (IAA), kinetin, 2,4-dichlorophenoxyacetic acid (2,4-D) and yeast ex tract, alone and in combination. The table shows the frequency of for mation of buds and roots as well as the general growth response of the callus in the various media. The growth of the callus was greatly en hanced by the addition of 2,4-D. Bud formation occurred in all media, including even the basal medium but was completely inhibited in the presence of 2,4-D. The callus was also grown in suspension cultures on a rotary shaker where also numerous embryoids arose. Many of these developed into leafy shoots.