Breeding strategies for mitigating cassava brown streak disease in Africa

Cassava (Manihot esculenta Crantz), is an important staple crop for about 800 million people worldwide, and a key commodity for the starch industry. However, the potential cassava production is limited by several biotic constraints amongst which cassava brown streak disease (CBSD) is the most economically important disease in Africa. To date, the most sustainable strategy to control CBSD is the use of resistant varieties and the supply of disease-free planting materials to cassava farmers. CBSD breeding activities were initiated in Tanzania in the 1930’s and Manihot glaziovii species was used as a donor parent to generate resistant hybrids. Joint regional initiatives through variety development and virus-elimination methods have been vital for CBSD management in the last two decades. While conventional breeding is tedious and sources of broad-spectrum resistance are not always available to improve cassava, new plant breeding technologies (NPBTs) appears as a valuable and complementary tool to generate virus resistance as well as to speed up and scale up cassava breeding efforts towards CBSD resistance. This review presents the breeding strategies which have so far been used to manage the CBSD disease and discusses the advantages of integrating NPBTs in current cassava breeding programs to rapidly deliver CBSD-resistant varieties to farmers in Africa.