A time for more booms and fewer busts? Unraveling cereal-rust interactions.

Recent advances in our understanding of the nature of resistance genes and rust fungus genomics are providing some insight into the basis of resistance and susceptibility to rust diseases in our cereal crops. Characterized rust resistance genes, for the most part, resemble other resistance genes that interact with effectors intracellularly, but some have unique features. Characterization of rust effectors is just beginning but genomic information and technical advances in rust functional genomics will accelerate their characterization. The ephemeral nature of resistance in past varieties has made the design of cultivars with durable resistance a major focus for geneticists and cereal breeders. This includes strategies for deploying race-specific resistance genes that prolong their effects and methods of predicting which will be difficult for the pathogen to defeat. Identification of resistance genes with race-nonspecific effects is another strategy where recent breakthroughs have been made. Routinely combining the numerous genes required for complex resistance, whether specific or nonspecific, in elite cultivars remains a primary constraint to realizing durable resistance in most programs.