In vitro germination and direct shoot induction of Yeheb (Cordeauxia edulis Hemsl.)

摘要

Yeheb' (Cordeauxia edulis Hemsl) is a multipurpose and evergreen shrub and endemic to southeastern corner of Ethiopia and Somalia. It is adapted to low and irregular rainfall and survives a very long dry season. It has enormous economic and food security role to the pastoralist of Somali in Ethiopia. However, the plant is threatened with extinction due to overexploitation and its' poor natural regeneration capacity. In addition, 'yeheb' is usually reported having limited reproductive capacities and often have very specific and limited conditions for seed germination, flowering and seed shelf life. Therefore, to overcome these propagation challenges, an experiment was conducted with the aim of developing a protocol for the in vitro regeneration of 'yeheb' from cotyledonary node. The result of these studies revealed that seed was washed by 5% sodium hypochlorite for ten min in aseptic condition found to be more effective in surface sterilization. The sterilized seed cultured on half strength of Gamborg (B5) medium was found to be the most suitable medium for germination (26.67%). The highest shoot initiation percentage (89 % of explants produces shoots), number of shoots per explant and number of leaf per shoot were obtained from cotyledonary node explants cultured on Murashige and Skoog (MS) media supplemented with 2.00 mg. l~(-1) N6-benzylaminopurine (BAP) within nine weeks. While, the highest shoot length and shoot fresh weight were recorded from control (free BAP) and 6.00 mg.l~(-1) BAP, respectively. The highest shoot multiplication (4.56 number of shoot induced) and elongation (2.97cm) were obtained from the induced shoot were cut and placed on MS media supplemented with 2.00 mg. l-1BAP+6.00 mg. l~(-1) of gibberellic acid (GA_3) and free BAP+6.00 mg.l~(-1) of GA_3, respectively. The elongated shoots were transferred to different media supplemented with various types and levels of hormones but none of them induced root. As a conclusion, this is the first attempt for direct in vitro regeneration of C. edulis and permissible result for cryopreservation.