Epidemiology and molecular characterization of quantitative trait loci (QTLs) for resistance to common rust (Puccinia sorghi) and gray leaf spot (Cercospora zeae maydis) diseases of maize in Ethiopia

Abstract

Maize (Zea mays L.) is an important component of farming systems and staple food crop in sub-Saharan Africa. In Ethiopia maize is a staple food and one of the main sources of calories in the major maize producing regions. It is cultivated on about 1.7 million hectares of land. The national average yield of maize under subsistence production is about 2200kg/ha. This is too much below the world’s average yield. This low yield is attributed to foliar diseases and insect pests such as stalk borer. One of the bottle necks in developing countries like Ethiopia which have lowered the yielding ability of maize is the usage of inferior genes which are susceptible to diseases, insects, weeds, low yield and quality. Another is lack of adequate investment and skilled manpower to improve varieties for high yield and disease resistance, diminishing land and water resources and environmental stresses. The most common potentially economic diseases on maize in Ethiopia are common rust and gray leaf spot.  Despite the presence of food shortage in Ethiopia, every year a heavy toll of maize yield is taken by these pathogens. For example, 23% yield reduction by common rust and 37% loss by gray leaf spot were recorded. Genomic research can provide new tools and resources to revolutionize crop genetic improvement and production. Recognizing the enormous potential of DNA markers in plant pathology and breeding, many agricultural research centers with plant pathology and breeding institutes in developed countries have adopted the capacity for marker development and marker-assisted selection (MAS) and due to rapid developments in marker technology, statistical methodology for identifying quantitative trait loci (QTLs) and the jargon used by molecular biologists, the utility of DNA markers in plant pathology and  breeding is clearly understood by molecular biologists. But these technologies are scanty in Ethiopia. Therefore, in this review epidemiology of these pathogens and molecular approaches helpful in boosting maize productivity were discussed. Hence, this information can help plant pathologists, plant breeders and geneticist to promote further studies in this new research area in Ethiopia.