Molecular characterization of the eukaryotic translation initiation factor 4E isoform,eIF(iso)4E, in traditional cultivars of Prunus domestica

A plum pox virus (PPV) susceptible traditional cultivar (Besztercei Bt.2) and a clone of a PPV resistant autochthonous landrace, Nemtudom (Nábrád) of the hexaploid European plum (Prunus domestica) were used to identify and characterize an isoform of the eukaryotic translation initiation factor, eIF(iso)4E, a host susceptibility factor required for PPV infection in plum. The cDNA and intron sequences of the eIF(iso)4E gene and the modeled 3D structure of the encoded proteins revealed sequence alterations that are not expected to critically influence the structure and function of the protein. The introns shared the canonical GT–AG splice sites, although they showed base substitutions and indels among alleles, and were different in intron phases. However, none of the sequence variations seem to challenge the splicing efficiency of the introns. The expression rates of the gene were similar in the leaves of the PPV susceptible Besztercei Bt.2 and the tolerant Nábrád cultivars, suggesting the eIF(iso)E4 gene is not responsible for differences in the reaction of those cultivars to PPV. Our results indicate natural differences in the PPV-tolerance of Besztercei Bt.2 and Nábrád were not induced by the eIF(iso)4E gene and hence the PPV tolerant Nábrád and other Nemtudom accessions might be valuable donors of PPV resistance in breeding programs. By providing the first information on the allelic variations, exon–intron structure, and expression of the eIF(iso)4E gene in P. domestica, our results will help in both conventional and molecular breeding of the studied and other European plum cultivars.