EDR1 encodes a putative mitogen‐activated protein kinase kinase kinase (MAPKKK), and is considered to be a negative regulator, because edr1 resistance is caused by the activation of multiple defence responses, including increased defence gene expression and accelerated cell death response at the site of infection (Frye and Innes, 1998; Frye et al., 2001). Here, PHC1 is linked to infection.