Resistance to TEV and LMV depends on different isoforms of eIF4E. A, Phylogenetic tree based on full length eIF4E1 and eIFiso4E protein sequences from Lycopersicon esculentum (Le), Capsicum annum (Ca), Lactuva sativa (Ls), Pisum sativum (Ps), Prunus domestica (Pd) and Arabidopsis thaliana (At). See methods for accession numbers. Bootstrap values over 0.6 supporting the branchpoints are represented. Resistance to potyviruses that have been reported both in Arabidopsis and in another plant species, namely TEV, LMV, ClYVV and PPV, are represented by a boxed virus abbreviation next to the 4E protein it has been shown to rely on (See Table 1 for references). B, Protein sequence alignment of Capsicum annuum and Arabidopsis thaliana eIF4E1 and eIFiso4E. Amino acids identical or similar among at least 3 sequences are highlighted in black and grey, respectively. Amino acids common only to either eIF4E1 or eIFiso4E sequences are highlighted in blue and green, respectively. Isoform-specific amino acids as defined by Monzingo et al.  are marked by an asterisk. eIF4E1 box I and II, marked in red, are clusters of natural variation involved in resistance to potyviruses, as defined by Robaglia and Caranta .