Evidence that the recessive bymovirus resistance locus rym4 in barley corresponds to the eukaryotic translation initiation factor 4E gene

Abstract

SUMMARY Recent studies have shown that resistance in several dicotyledonous plants to viruses in the genus Potyvirus is controlled by recessive alleles of the plant translation initiation factor eIF4E or eIF(iso)4E genes. Here we provide evidence that the barley rym4 gene locus, controlling immunity to viruses in the genus Bymovirus, corresponds to eIF4E. A molecular marker based on the sequence of eIF4E was developed and used to demonstrate that eIF4E and rym4 map to the same genetic interval on chromosome 3HL in barley. Another genetic marker was developed that detects a polymorphism in the coding sequence of eIF4E and consistently distinguishes between rym4 and susceptible barley cultivars of diverse parentage. The eIF4E gene product from barley genotypes carrying rym4 and allelic rym5 and rym6 genes, originating from separate exotic germplasm, and a novel resistant allele that we identified through a reverse genetics approach all contained unique amino acid substitutions compared with the wild-type protein. Three-dimensional models of the barley eIF4E protein revealed that the polymorphic residues identified are all located at or near the mRNA cap-binding pocket, similarly to recent findings from studies on recessive potyvirus resistance in dicotyledonous plants. These new data complement our earlier observations that specific mutations in bymovirus VPg are responsible for overcoming rym4/5-controlled resistance. Because the potyviral VPg is known to interact with eIF4E in dicotyledonous plants, it appears that monocotyledonous and dicotyledonous plants have evolved a similar strategy to combat VPg-encoding viruses in the family Potyviridae.

Plant Immune Responses Against Viruses: How Does a Virus Cause Disease?

“…For example, amino acid mutations in the eukaryotic translation initiation factor, eIF4E, mediates resistance against several viruses in Arabidopsis, tomato, pepper, pea (Pisum sativum), melon (Cucumis melo), and barley (Hordeum vulgare) (Lellis et al, 2002;Ruffel et al, 2002Ruffel et al, , 2005Nicaise et al, 2003;Gao et al, 2004;Kanyuka et al, 2005;Piron et al, 2010). In addition, mutations in another subunit of eukaryotic translation initiation factor, eIF4G, imparts recessive resistance against Rice yellow mottle virus (RYMV) in rice (Oryza sativa) (Albar et al, 2006) and to CMV and TCV in Arabidopsis (Yoshii et al, 2004).…”

Mutational Analysis of Plant Cap-Binding Protein eIF4E Reveals Key Amino Acids Involved in Biochemical Functions and Potyvirus Infection

“…The pvr2 locus in pepper, mo1 in lettuce, and sbm1 in pea confer resistance, respectively, against Potato virus Y (64) and TEV (27), LMV (48), and Pea seed-borne mosaic virus (18). The barley rym4/5/6 resistance genes to various strains of the bymoviruses (belonging to the family Potyviridae) Barley yellow mosaic virus and Barley mild mosaic virus were also found to be mutations in the eIF4E gene (29,73). Furthermore, the nsv locus in melon that confers resistance to a non-Potyviridae, uncapped, and nonpolyadenylated virus, Melon necrotic spot virus, also encodes eIF4E (51).…”

Transcriptome profile of early responsive genes in susceptible barley duringRhynchosporium secalisinfection

“…Additionally, formins (fragment 38; JZ820450) was identified 3 days post infection and could play a role in cytoskeleton, plasma membrane and cell-wall linkages related to defense responses (Cushman 2001). Interestingly, Rym4 (JZ820450) appeared at 2 days of inoculation, which is the recessive by movirus resistance locus in barley corresponding to the eukaryotic translation initiation factor 4E gene (Kanyuka et al 2005).…”