Plant diseases caused by a wide variety of pathogens have had tremendous negative impacts on human beings.For example,the oomycete pathogen Phytophthora infestans,which causes severe late blight disease on potatoes,triggered the infamous Irish Potato Famine.To prevent such tragedies from happening again and to reduce crop losses,it is imperative to implement effective disease control and management strategies.A deeper and more comprehensive understanding of how plant pathogens cause disease is critical for developing novel and effective strate-gies for controlling plant diseases.