title: Mapping and candidate-gene screening of the novel Turnip mosaic virus resistance gene retr02 in Chinese cabbage (Brassica rapa L.).
abstract: The extreme resistance to Turnip mosaic virus observed in the Chinese cabbage (Brassica rapa) line, BP8407, is monogenic and recessive. Bulked segregant analysis was carried out to identify simple sequence repeat and Indel markers linked to this recessive resistance gene, termed recessive Turnip mosaic virus resistance 02 (retr02). Mapping of PCR-specific Indel markers on 239 individuals of a BP8407 × Ji Zao Chun F(2) population, located this resistance gene to a 0.9-cM interval between two Indel markers (BrID10694 and BrID101309) and in scaffold000060 or scaffold000104 on chromosome A04 of the B. rapa genome. Eleven eukaryotic initiation factor 4E (eIF4E) and 14 eukaryotic initiation factor 4G (eIF4G) genes are predicted in the B. rapa genome. A candidate gene, Bra035393 on scaffold000104, was predicted within the mapped resistance locus. The gene encodes the eIF(iso)4E protein. Bra035393 was sequenced in BP8407 and Ji Zao Chun. A polymorphism (A/G) was found in exon 3 between BP8407 and Ji Zao Chun. This gene was analysed in four resistant and three susceptible lines. A correlation was observed between the amino acid substitution (Gly/Asp) in the eIF(iso)4E protein and resistance/susceptibility. eIF(iso)4E has been shown previously to interact with the TuMV genome-linked protein, VPg.
authors.affiliation: Department of Chinese Cabbage, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China. qian0wei@163.com
authors.forename: Wei
authors.initials: W
authors.lastname: Qian
authors.forename: Shujiang
authors.initials: S
authors.lastname: Zhang
authors.forename: Shifan
authors.initials: S
authors.lastname: Zhang
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.forename: Xiaowu
authors.initials: X
authors.lastname: Wang
authors.forename: John A
authors.initials: JA
authors.lastname: Walsh
authors.forename: Rifei
authors.initials: R
authors.lastname: Sun
mesh_terms: D000595:Amino Acid Sequence; D029741:Brassica rapa / Q000235:genetics*; D002874:Chromosome Mapping / Q000379:methods; D003433:Crosses, Genetic; D017343:Genes, Plant; D005808:Genes, Recessive; D005819:Genetic Markers / Q000235:genetics; D018745:Genome, Plant; D018895:Microsatellite Repeats / Q000235:genetics; D008957:Models, Genetic; D015233:Models, Statistical; D008969:Molecular Sequence Data; D009029:Mosaic Viruses / Q000235:genetics*; D010641:Phenotype; D020161:Physical Chromosome Mapping; D010935:Plant Diseases / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D005819:Genetic Markers