Fig. 8: Model for evolution of Rcr3.
From: Evolution of a guarded decoy protease and its receptor in solanaceous plants
a Cf-2 evolved in wild tomato <8 Million years ago (<8Mya) by co-opting existing SpRcr3. Rcr3 and its paralog Pip1 evolved >50Mya and occur in all solanaceous species. NbRcr3 and NbPip1 in N. benthamiana carry deleterious mutations that occurred repeatedly in N. benthamiana species <5Mya. b–e Rcr3 needs to interact with both Avr2 and Cf-2 to trigger HR. b Both tomato and potato Rcr3 (e.g., SpRcr3) interact with Avr2 and Cf-2 and trigger HR. c Eggplant Rcr3 (SmRcr3) has a strong interaction with Avr2 but cannot trigger HR with Cf-2, presumably because it is unable to interact properly with Cf-2. d Pepper Rcr3 (CaRcr3) has a weak interaction with Avr2, but can trigger HR by introducing residues that enhance the interaction with Avr2. e Tobacco Rcr3 (NtRcr3) has low affinity to Avr2 and cannot trigger HR even when engineered to increase its interaction with Avr2.
