Cloning and Expression Analysis of eIF4E Gene in Tobacco Mutants Resistant to PVY^N

In order to explore PVY resistance-related gene and further reveal its resistance mechanism, the tobacco mutants SN01 and SN02 highly resistant to potato virus Y vein necrosis strain (PVY^N) were experimented to study the role of translation initiation factor eIF4E of PVY resistance-related gene in the mutants. The results showed that full length target genes were successfully cloned from the mutants SN01 and SN02. The genes were referred to as eIF4E01 and eIF4E02, respectively; their open reading frame (ORF) was 669 bp in length and encoded a protein of 222 amino acids. The homology analysis by MEGA 4.1 and CLUSTAL showed that these genes possessed 99% sequence similarities to and exactly the same ORF sequence as reported eIF4E in tobacco (GenBank: AY702653.1), they were highly homologous to the eIF4E family genes in Capsicum annuum, Lycopersicon esculentum and Arabidopsis thaliana. Real-time PCR results indicated that the expression level of eIF4E in the mutants was obviously lower than that in their susceptible parents NC89 and K326 at the early stage of PVY^N infection (0-9 days after inoculation), it indicated that the suppression of eIF4E expression in the two mutants was closely related to the resistance of tobacco to PVY^N.