Plant regeneration from stem segment-derived friable callus of “Fonio” ( Digitaria exilis (L.) Stapf.)

Abstract

“Fonio” ( Digitaria exilis (L.) Stapf.) is a member of the grass family with excellent culinary and nutritional properties. In spite of its economic values, hardly has any improvement work been done. To enhance genetic improvement of this grain, plant regeneration protocol was developed using 8 cultivars. Stem segments of 5 mm long excised from 1 month-old seedlings germinated in vitro were cultured on 6 types of media for friable callus induction. Best result was obtained on Murashige and Skoog (MS) medium supplemented with 2 mg l −1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1 g l −1 casamino acid, where 91.3, 88.9 and 87.8% of the explants formed friable calli in cultivars ‘Kurelep’, ‘Churiwe’ and ‘Agyong’, respectively. Shoots appeared when friable calli were transferred to two regeneration media, i.e., MSBZ (MS medium + 0.022 mg l −1 2,4-D, 0 .22 mg l −1 6-benzylaminopurine (BA), 0.22 mg l −1 zeatin) and MSBG (MS medium + 0.5 mg l −1 BA, 0.1 mg l −1 gibberellic acid). The highest frequency of plant regeneration was attained on MSBG, with 91.7% of the friable calli forming shoots in cultivar “Churiwe”. Regenerated plants were rooted on hormone free MS medium. Flow cytometric analysis revealed 100% of the regenerants to be diploid. The protocol developed here can be used in the transformation of “Fonio” to increase the yield potential of this crop by incorporating characteristics such as disease resistance and stress resistance.