Pantnagar Journal of Research

Abstract

The pathogenic fungi are highly diverse and utilize distinct strategies to interact with the host plant. Despite the diversity among these all fungi that colonize plants are recognized by the plant innate immune system, which elicits a host defense response. The innate immune perception triggers both local and systemic reactions, allowing a plant to respond to pathogen attack in a quick and localized manner over an extended period of time. It is accepted that most fungal avirulence genes encode virulence factors that are called effectors which are cysteine rich proteins. These proteins, first discovered because of their ability to trigger the hypersensitive response in resistant plants ("avirulence"activity), were later found to contribute to virulence in susceptible plants, typically host plants that lack effective resistance [R] genes. Over the past two decades, several novel Avr genes and cognate R gene have been discovered. The review provides a brief description of what are effector proteins, their types produced in the case of different host pathogen interaction, the mechanism involved and novel effectors. The focus has been given on effector molecules of biotrophic and hemibiotrophic fungi, responsible for triggering immunity or activating host defense response.