Wild-type and mutant Rpg1-mediated reaction to infection with race MCCF and QCCJ. Columns from left to right show cartoon Rpg1 structure with mutated amino acids indicated; disease reaction phenotype; RPG1 protein response to infection timed in hours; and kinase autocatalytic activity measured in vitro. Lane 1 from top indicates kinase domain 2 mutant with K461 and K462 converted to N and Q, respectively. The resulting mutant transgenic in ‘Golden Promise’ genomic background is highly susceptible to race MCCF, the RPG1 protein is not degraded in 60 h, and it has no kinase activity. Compare with Lane 2, showing kinase domain 1 mutant with K152 and K153 mutated to N and Q, respectively. This transgenic mutant is also highly susceptible to race MCCF, the RPG1 protein is not degraded in 60 h, but it retains kinase activity, indicating that kinase domain 2 is sufficient for kinase activity, but kinase domain 1 is also required for disease resistance. Compare both with wild-type Rpg1 transgenic (GP/Rpg1T1) in Golden Promise (GP) genomic background (Lane 3) and GP control (Lane 6), which does not have a detectable Rpg1 gene or protein. RPG1 protein in GP/Rpg1T1 is degraded 20 to 28 h after infection, indicating that protein degradation is associated with disease resistance. Autocatalytic kinase activity is present. ‘Morex’ (Lanes 4 and 5) with wild-type Rpg1 shows resistance to race MCCF but susceptibility to race QCCJ. The RPG1 protein is degraded between 20 and 28 h in MCCF infection but not with QCCJ infection, indicating that RPG1 degradation is a specific response to infection with avirulent, but virulent races. Autocatalytic activity is retained in both cases.