Resumen
- Cassava [Manihot esculenta Crantz ( Euphorbiacee)], a starchy root crop, is native to South America and is one of the most important tropical food crops. Cassava is an important source of carbohydrates for over 500 million people. It is also used for animal feed and as raw material for the industrial processing of starch-based products. Viral and bacterial diseases are major contributors to yield reductions in Africa and South America, threatening food security in severe cases. Cassava Mosaic Disease (CMD), caused by a complex of geminiviruses, represents a major constraint on cassava production in Africa, while Cassava Bacterial Blight (CBB) is an important disease, endemic in Latin America and Africa. CBB is caused by the bacteriumXanthomonas axonopodis pv. manihotis ( Xam), a foliar and vascular pathogen (Lozano and Sequeira 1974). Host plant resistance is the principal method of CMD and CBB control. Resistance to both diseases has been developed from M. esculenta and its wild relative M. glaziovii, and may be polygenic and additively inherited (Hahn et al. 1980). A correlation was observed between resistance to CMD and CBB, suggesting either that resistance factors to each are located in the same region of the genome or that a common factor confers resistance to both diseases.