Plant resistance and strategies for breeding resistant varieties

An explanation of the 'boom-bust' cycle of resistance breeding was provided by the gene-for-gene relationship between a pathogen and its host. Despite this understanding, most R genes continued to be deployed singly and resistance has been ephemeral. The reasons for breeding 'single R gene' varieties are discussed. Alternative strategies for the deployment of R genes and the use of quantitative race non-specific resistance have been advocated in order to obtain durable resistance. The feasibility of both of these approaches is discussed taking into account the impact of technologies such as plant transformation and marker-assisted selection. A change in focus from durability of the plant phenotype to that of the crop phenotype is advocated.