Journal: Plant Biotechnology Journal
Article Title: Edited eukaryotic translation initiation factors confer resistance against maize lethal necrosis
doi: 10.1111/pbi.14472
Figure Lengend Snippet: Wild‐type eIF4E2 protein and its natural and edited variants in maize (a), and the effect of different combinations of eif4e1‐KO and eIF4E2ED variants on viral replication and plant growth. KO, knockout; X, no growth; − no host; √, normal growth. The numbers in the respective horizonal bars are for the amino acids. (a) The wild‐type eIF4E2 in maize is 220 amino acids long. A naturally occurring variant in Mini Maize has an in‐frame deletion of 22 amino acids corresponding to the 4th exon. Some of the edited variants in eIF4E2 from an elite line, CKL05022, are shorter by nearly the entire stretch of C‐terminal 38 amino acids. (b) Effect of combinations of a knocked‐out eIF4E1 (218 amino acids long) and different variants of eIF4E2 on MLN resistance. Aside from the naturally occurring variant of eIF4E2 in Mini Maize, any frameshift mutation in the 4th exon resulted in complete MLN resistance. In addition to frameshift mutants, we obtained at least two in‐frame mutants that lacked either the first four amino acids (181–184) in CKL05022 (Figure , event 2) or the first six amino acids (183‐188) in CML536 (Figure , event 3) corresponding to the 4th exon that were completely resistant to MLN. The C‐terminal 38 amino acids appear to constitute a domain that is required for recognition by the viruses to translate their proteins but is not necessary for the translation of the maize proteins. The two eIF4E proteins differ only at two positions in the C‐terminal 38‐aa stretch (Figure ). Designing a single guide RNA around the junction of the 3rd intron/4th exon for both the eIF4E1 and eIF4E2 genes would expedite the introduction of MLN resistance in susceptible elite lines. These findings could be extrapolated to other plant species to develop broad‐spectrum resistance against viruses.
Article Snippet: For overexpression of the full‐length eIF4E2 gene, a construct containing a full‐length eIF4E2 cDNA corresponding to the CML536 gene was synthesised (GenScript) and transformed into the eif4e1‐KO Mini Maize under the control of the ZmUbi1‐intron promoter.
Techniques: Knock-Out, Variant Assay, Mutagenesis