Abstract

Sweet potato is one of the main staple food crops for millions of subsistence farmers in Africa.  Biotic and abiotic stresses and socio-economic challenges are the major production constraints of the crop. Amongst biotic constraints, the sweet potato virus disease (SPVD) is the most devastating causing yield reduction ranging from 50 to 98%. This paper highlights the progresses and challenges of breeding sweet towards improved yield and SPVD resistance. Further, the potential and limitations of non-conventional breeding techniques for sweet potato improvement have been reviewed. Both improved cultivars and landraces that are presently grown succumb to SPVD and several viral diseases. The yield losses caused by SPVD have significant negative impact on food security and income for the rural poor. Continued use of susceptible varieties, absence of high yielding and early maturing resistant varieties, and lack of effective control measures to SPVD contribute to low yields and disease build up, development and persistence. Both chemical and biological control methods are not effective against viral diseases. The use of resistant varieties remains the most effective and cheapest method for small-scale farmers. Breeding for resistance against SPVD is remains the most important component to improve yield and reduce the impact of SPVD. Reduced flowering and fertility, self- or cross-incompatibility are the major challenges of conventional breeding in sweet potato breeding. The use new breeding techniques such as marker-assisted selection and genetic engineering could have complementary roles in sweet potato breeding. This review provides theoretical bases on the progress and challenges for breeding sweet potato for SPVD resistance and improved yields.

Key words: Breeding, resistance, sweet potato virus disease (SPVD), sweet potato, viral disease, yield.