The identification of eIF4E as the causal host factor for Sugarcane streak mosaic virus resistance

Abstract Sugarcane mosaic disease, mainly caused by Sugarcane streak mosaic virus (SCSMV), has serious adverse effects on the yield and quality. Eukaryotic translation initiation factor 4E ( eIF4E ) is a natural resistance gene in plants. The eIF4E-mediated natural recessive resistance comes from non-synonymous mutations of the eIF4E protein. In this study, two sugarcane varieties (CP94-1100 and ROC22) with different resistance to SCSMV were selected for the analysis of the differences in sugarcane resistance. The result showed that the nucleotide and amino acid sequences of the CP and VPg of SCSMV an between varieties were highly consistent and belong to the same isolate. However, four base missense mutations in the ORF region of eIF4E resulted in different conserved domains. Therefore, the difference in resistance comes from the differences in the eIF4E gene of the sugarcane varieties themselves. The coding region of eIF4E gene were 28 SNP loci, no InDel loci, and affected by negative selection, and was relatively conserved. A total of 11 haploids encoded 11 protein sequences. Protein spatial structure prediction revealed three amino acid non-synonymous mutations sites located in the cap pocket of eIF4E, among which one site only existed in a resistant material (Yuetang 55) and one site only existed in a susceptible material (ROC22), suggesting that the two sites might be related to the resistance to SCSMV. These results provide a strong basis for further analysis of the functional role of eIF4E in regulating mosaic resistance in sugarcane and developing resistance varieties.