Application of biotechnology for the domestication of Dacryodes edulis (G. Don) H. J. Lam in Cameroon: A review

Cultivation of Dacryodes edulis (G. Don) H. J. Lam commonly known as safou to improve the livelihood of the local population has been growing rapidly in the range of occurrence of safou and recent emergence of the market chain introduced by the World Agroforestry Center (ICRAF) experts has stimulated this further. Domestication through conventional genetic improvement (breeding) of safou has relied on phenotype selection and quantitative genetics through field trials breeding. Technologies to increase productivity, increase sustainable resource use, respond to climate change and enhance efficiency are required to meet demand. Biotechnology applications give a scope for rapid improvement and also facilitate the breeding program. Advantages of biotechnology application using molecular markers in breeding programs includes: study of genetic diversity, DNA fingerprinting of individuals, easy identification of specific traits or genes of interest, rapid propagation of improved genotypes and integration of gene(s) of interest into the species. It also provides genetic basis for selecting individuals and particular regions of the genome in a breeding program, reduce breeding population, can lead to early selection of traits and the development of a new variety with combination of characteristics. The complementary role of these techniques will be necessary for a successful genetic improvement program in the species. This review examines the achievements obtained using classical techniques, emphasizes missing gaps for the application of molecular techniques and discusses the complementary role of biotechnology techniques for a sustainable genetic improvement program in the species.Keywords: Dacryodes edulis, domestication, population, genetic diversity, multiplication, biotechnology and genetic improvemen

Nursery substrates and provenances influence rooting performance of juvenile, single-node vine cuttings of Gnetum africanum Welw. (Gnetaceae)

Gnetum africanum Welw. (Gnetaceae) is a forest vine that is highly valued for its leaves which are a source of food and income. Because wild populations are threatened by over-harvesting, there is an increasing need to cultivate the plant, which in turn entails a need for developing good quality planting material. This study investigates the effects of four provenances, four substrates and their interactions on rooting and shoot development of vine cuttings of G. africanum using the non-mist propagation system developed by ICRAF. Single-node, half-leafed vine cuttings were used and data on rooting and leaf production were collected monthly from the second to the fifth months. Rooting percentages were subjected to analysis of variance using logistic regression procedures in Genstat version 12. Provenance (P<0.001), substrate (P<0.001) and interaction between provenance and substrate (P<0.001) showed highly significant effects on rooting. Excel was used to determine rooting percentages, with the highest observed in fine sand on cuttings from Lekie-Assi (81%) and Boumnyebel (79%) which are high G. africanum exploitation areas in the Centre Region of Cameroon. Boumnyebel showed a significantly higher shoot development than the other provenances. Fine sand and sharp sand can be recommended for rapid, low-cost production of G. africanum planting material