EcoTILLING for the identification of allelic variants of melon eIF4E, a factor that controls virus susceptibility.
BACKGROUND
Translation initiation factors of the 4E and 4G protein families mediate resistance to several RNA plant viruses in the natural diversity of crops. Particularly, a single point mutation in melon eukaryotic translation initiation factor 4E (eIF4E) controls resistance to Melon necrotic spot virus (MNSV) in melon. Identification of allelic variants within natural populations by EcoTILLING has become a rapid genotype discovery method.


RESULTS
A collection of Cucumis spp. was characterised for susceptibility to MNSV and Cucumber vein yellowing virus (CVYV) and used for the implementation of EcoTILLING to identify new allelic variants of eIF4E. A high conservation of eIF4E exonic regions was found, with six polymorphic sites identified out of EcoTILLING 113 accessions. Sequencing of regions surrounding polymorphisms revealed that all of them corresponded to silent nucleotide changes and just one to a non-silent change correlating with MNSV resistance. Except for the MNSV case, no correlation was found between variation of eIF4E and virus resistance, suggesting the implication of different and/or additional genes in previously identified resistance phenotypes. We have also characterized a new allele of eIF4E from Cucumis zeyheri, a wild relative of melon. Functional analyses suggested that this new eIF4E allele might be responsible for resistance to MNSV.


CONCLUSIONS
This study shows the applicability of EcoTILLING in Cucumis spp., but given the conservation of eIF4E, new candidate genes should probably be considered to identify new sources of resistance to plant viruses. Part of the methodology described here could alternatively be used in TILLING experiments that serve to generate new eIF4E alleles.
Nieto
Cristina
C
Centro de Edafología y Biología Aplicada del Segura-CSIC, Espinardo, Murcia, Spain. agr009@cebas.csic.es
Piron
Florence
F
Dalmais
Marion
M
Marco
Cristina F
CF
Moriones
Enrique
E
Gómez-Guillamón
Ma Luisa
ML
Truniger
Verónica
V
Gómez
Pedro
P
Garcia-Mas
Jordi
J
Aranda
Miguel A
MA
Bendahmane
Abdelhafid
A
D000483:Alleles; D019184:Carmovirus / Q000502:physiology*; D028463:Cucumis melo / Q000235:genetics* / Q000821:virology; D039561:Eukaryotic Initiation Factor-4E / Q000235:genetics*; D005821:Genetic Techniques; D005838:Genotype; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000821:virology; D011110:Polymorphism, Genetic; D019176:Potyviridae / Q000502:physiology*
D039561:Eukaryotic Initiation Factor-4E