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. 2025 Jul 28;17(8):1050.
doi: 10.3390/v17081050.

Deciphering Cowpea Resistance to Potyvirus: Assessment of eIF4E Gene Mutations and Their Impact on the eIF4E-VPg Protein Interaction

Fernanda Alves de Andrade  1 , Madson Allan de Luna-Aragão  2 , José Diogo Cavalcanti Ferreira  3 , Fernanda Freitas Souza  1 , Ana Carolina da Rocha Oliveira  1 , Antônio Félix da Costa  4 , Francisco José Lima Aragão  5 , Carlos André Dos Santos-Silva  6 , Ana Maria Benko-Iseppon  1 , Valesca Pandolfi  1
Affiliations

Deciphering Cowpea Resistance to Potyvirus: Assessment of eIF4E Gene Mutations and Their Impact on the eIF4E-VPg Protein Interaction

Fernanda Alves de Andrade et al. Viruses. .

Abstract

Cowpea (Vigna unguiculata) is a crop of significant socioeconomic importance, particularly in the semi-arid regions of Africa and America. However, its productivity has been adversely affected by viral diseases, including the cowpea aphid-borne mosaic virus (CABMV), a single-stranded RNA virus. It is known that the VPg protein interacts with the host's translation initiation factor (eIF4E), promoting viral replication. This study aimed to investigate the relationship between mutations in the cowpea eIF4E gene and resistance to CABMV. Twenty-seven cultivars were screened by PCR and bioassays for presence/absence of mutations associated with resistance or susceptibility to Potyviruses. Of the cultivars with mutations previously associated with susceptibility, 88.24% exhibited viral symptoms, while 62.5% associated with resistance remained asymptomatic. The in silico analyses revealed that non-synonymous mutations (Pro68Arg, Gly109Arg) alter the structure of the eIF4E protein, reducing its affinity to VPg. Molecular dynamics simulations also pointed to an enhanced structural stability of eIF4E in resistant cultivars and reinforced, for the first time, key mutations and the functional role of the eIF4E gene in resistance to CABMV in cowpea. Our results offer valuable insights for virus disease management and for genetic improvement programs for this important crop.

Keywords: CABMV; Vigna unguiculata; recessive resistance; translation initiation factor 4E.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Representative symptoms exhibited by the cowpea cultivars inoculated with cowpea aphid-borne mosaic virus (CABMV): (A) Leaf distortions and mosaic symptoms. (B) Comparison of cowpea cultivars: (B1) asymptomatic plant and (B2) infected plant showing mosaic symptoms and reduced leaf size. (C) Severe mosaic. (D) Mosaic and green stripes along the veins. (E) Healthy leaf from a resistant cultivar (IT85F-2687).
Figure 2
Figure 2
Conserved domain analysis. (A) Conserved domain of the eIF4E protein from five cowpea cultivars (Bajão, Boca Negra, BRS Cauamé, BRS Xiquexique, and IT85F-2687). (B) Conserved domain of the VPg protein from CABMV (cowpea aphid-borne mosaic virus). The red circle (position 64) in the VPg sequence highlights the tyrosine (Tyr) residue essential for the VPg uridylylation process.
Figure 3
Figure 3
Alignment between the theoretical three-dimensional models of eIF4E proteins. (A) Alignment of the three-dimensional structures of cowpea eIF4E proteins with A. thaliana eIF4E, RMSD of 0.576 Å (PYMOL v.3.1). (B) Three-dimensional structure of the VPg protein from the CABMV Potyvirus.
Figure 4
Figure 4
Evaluation of the structural convergence of V. unguiculata eIF4E proteins. (A) RMSD of isolated eIF4E proteins; (B) RMSD of eIF4E proteins after docking with VPg.
Figure 5
Figure 5
Evaluation of the flexibilities of the three-dimensional structures of V. unguiculata eIF4E. (A) RMSF of isolated eIF4E proteins. (B) RMSF of eIF4E proteins after docking with VPg.
Figure 6
Figure 6
Evaluation of the intramolecular hydrogen bonds (HBs). (A) Number of intramolecular HBs in isolated eIF4E proteins; (B) number of intramolecular HBs after interaction with the VPg protein (eIF4E-VPg).
Figure 7
Figure 7
Evaluation of the radius of gyration (RG) of eIF4E proteins. (A) RG of isolated eIF4E proteins; (B) RG after docking with VPg (eIF4E-VPg).
Figure 8
Figure 8
Evaluation of the electrostatic surface profiles of eIF4E structures from cowpea cultivars and the VPg protein from CABMV Potyvirus. Dots highlight the eIF4E-VPg interaction regions with anionic (green circle) and cationic charges (yellow circle), respectively. (A) VPg; (B) VPg’s eIF4E binding site; (C) Boca Negra; (D) IT85F-2687; (E) Bajão; (F) BRS Xiquexique; (G) BRS Cauamé.
Figure 9
Figure 9
Schematic representation of the interaction areas in Å2 of the VPg-eIF4E complex and the corresponding Gibbs free energy difference (Theorical DDG), expressed in Rosetta Energy Units (REUs). (A) Boca Negra; (B) IT85F-2687; (C) Bajão; (D) BRS Xiquexique; (E) BRS Cauamé.
Figure 10
Figure 10
Highlighted representation of arginine (blue), glutamate (orange), glutamine (magenta), alanine (yellow), proline (tan), glycine (lime), valine (red), and tryptophan (purple) residues in V. unguiculata in the VPg-binding pocket of eIF4E proteins. (A) Boca Negra; (B) IT85F-2687; (C) Bajão; (D) BRS Xiquexique; (E) BRS Cauamé.
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