Agrobacterium-mediated genetic transformation of Fonio (Digitaria exilis (L.) Stapf)

Fonio (Digitaria exilis) is a crop grown in Africa for its excellent culinary and nutritional properties and is a valuable source of income for smallholder farmers. Its improvement has long been neglected by scientists because the crop was one of the lost crops of Africa. Recent advances in Fonio research are centered on its evolution, nutritional and economic values. The lack of a transformation and other biotechnology protocols developed for Fonio has greatly hindered genetic improvement of this crop. In this study, Agrobacterium-mediated genetic transformation was developed for two genotypes of D. exilis (‘Agyong’ and ‘Churiwe’). Three-weeks-old callus derived from stem segments were co-cultivated with Agrobacterium tumefaciens for 3 days. After selection on Hygromycin B medium, plants were regenerated on Murashige and Skoog (MS) medium supplemented with 0.5 mg l-1 BA and 0.1 mg l-1 gibberellic acid. Regenerated shoots were rooted on hormone-free MS medium. Histochemical gus assay and polymerase chain reaction (PCR) confirmed the presence of the gus gene in transformed tissues. The transformation frequency was 2.1 and 2.7% for “Agyong” and “Churiwe”, respectively. The transgenic plants were phenotypically normal. This protocol would provide useful platform for genetic improvement of this crop. Key words: Digitaria exilis. Transfomation efficiency, β-glucuronidase (GUS) assay, Agrobacterium tumefaciens.