A natural recessive resistance gene against potato virus Y in pepper corresponds to the eukaryotic initiation factor 4E (elF4E)

Abstract

We show here that the pvr2 locus in pepper, conferring recessive resistance against strains of potato virus Y (PVY), corresponds to a eukaryotic initiation factor 4E (elF4E) gene. RFLP analysis on the PVY-susceptible and resistant pepper cultivars, using an elF4E cDNA from tobacco as probe, revealed perfect map cosegregation between a polymorphism in the elF4E gene and the pvr2 alleles, pvr21 (resistant to PVY-0) and pvr22 (resistant to PVY-0 and 1). The cloned pepper elF4E cDNA encoded a 228 amino acid polypeptide with 70-86% nucleotide sequence identity with other plant elF4Es. The sequences of elF4E protein from two PVY-susceptible cultivars were identical and differed from the elF4E sequences of the two PVY-resistant cultivars Yolo Y (YY) (pvr21) and FloridaVR2 (F) (pvr22) at two amino acids, a mutation common to both resistant genotypes and a second mutation specific to each. Complementation experiments were used to show that the elF4E gene corresponds to pvr2. Thus, potato virus X-mediated transient expression of elF4E from susceptible cultivar Yolo Wonder (YW) in the resistant genotype YY resulted in loss of resistance to subsequent PVY-0 inoculation and transient expression of elF4E from YY (resistant to PVY-0; susceptible to PVY-1) rendered genotype F susceptible to PVY-1. Several lines of evidence indicate that interaction between the potyvirus genome-linked protein (VPg) and elF4E are important for virus infectivity, suggesting that the recessive resistance could be due to incompatibility between the VPg and elF4E in the resistant genotype.