Putative mechanistic conservation of NDR1 function. (a) Alignment of RIN4 homologous sequences. The closest sequence homologs of AtRIN4 [AGI:At3g25070] were aligned with the putative coffee RIN4 protein [harvEST:Coffea:UG5351] using ClustalX . The positions of the two AvrRpt2 cleavage sites [37, 38] are highlighted in red. Accession numbers of the genes coding for the proteins presented in the figure are as follows: Glycine max Gm [GenBank:ADJ67468]; Medicago truncatula Mt [GenBank:ACJ83941]; Populus trichocarpa Pt [GenBank:XP_002301798]; Vitis vinifera, Vv [GenBank:CBI33050]. (b) Scheme showing how NDR1 is anchored to the plasma membrane. AtNDR1 indirectly retains both R-proteins, RPS2 and RPM1, at the plasma membrane via its interaction with RIN4 [24, 48]. (c) Comparison of the N-terminal portions of the two orthologous NDR1 proteins from A. thaliana and C. arabica. Amino-acid residues necessary for the interaction with AtRIN4 are highlighted in red. Intriguingly, these residues do not seem to be conserved in the coffee sequence.