Prospects for understanding avirulence gene function

Avirulence genes are originally defined by their negative impact on the abi lity of a pathogen to infect their host plant. Many avirulence genes are no w known to represent a subset of virulence factors involved in the mediatio n of the host-pathogen interaction characterization of avirulence genes has revealed that they encode an amazing assortment of proteins and belong to several gene families. Although the biochemical functions of the avirulence gene products are unknown, studies are beginning to reveal the features an d interesting relationships between the avirulence and virulence activities of the proteins, Identification of critical virulence factors and elucidat ion of their functions promises to provide insight into plant defense mecha nisms, and new and improved strategies for the control of plant disease.