Breeding for Disease Resistance in Maize

Abstract

The maize production environments in sub-Saharan Africa (SSA) are conducive to the development of many disease-causing organisms, which have infected the crop, causing serious reduction in maize production and productivity. Some maize diseases infect maize in all SSA ecologies, while some others are specific to some environments and absent from others. The prominent maize diseases in SSA changed over time, and presently, the most devastating are gray leaf spot (GLS), incited by Cercospora zeae-maydis; northern corn leaf blight, incited by Exserohilum turcicum; southern corn rust (Puccinia polysora); maize streak virus (MSV) disease, transmitted by the leafhopper, Cicadulina mbila; downy mildew, by Peronosclerospora sorghi; ear rots, incited by several fungi, including Aspergillus sp. and Fusarium sp.; and the recently discovered disease that is spreading fast across SSA, the maize lethal necrosis (MLN), a disease incited by the synergistic effect of maize chlorotic mottle virus (MCMV; Tombusviridae: Machlomovirus) and several other potyvirus, such as maize dwarf mosaic virus (MDMV), sugarcane mosaic virus (SCMV), and wheat streak mosaic virus (WSMV). There are several methods used for disease control, but the most effective and economic method is breeding for host plant resistance. In this chapter, four case studies of this breeding approach are presented and their effectiveness in SSA clearly highlighted.