Fine genetic mapping of the white immature fruit color gene w to a 33.0-kb region in cucumber (Cucumis sativus L.)

• Published in: Theoretical and applied genetics 2015-12, Vol.128 (12), p.2375-2385
• Main Authors: Liu, Hanqiang, Meng, Huanwen, Pan, Yupeng, Liang, Xinjing, Jiao, Jianqing, Li, Yuhong, Chen, Shuxia, Cheng, Zhihui
• Format: Article
• Language: English
• Subjects: Agriculture; Amino Acid Sequence; Biochemistry; Biomedical and Life Sciences; Biotechnology; Chromosome Mapping; Chromosomes, Plant; Cloning; Color; Cucumbers; Cucumis sativus; Cucumis sativus - enzymology; Cucumis sativus - genetics; Cultivars; DNA, Plant - genetics; Fruit - genetics; Genes; Genes, Plant; Genes, Recessive; Genetic Loci; Genetic Markers; Genomes; Life Sciences; Molecular Sequence Data; Original Article; Peroxidases - genetics; Phenotype; Plant Biochemistry; Plant Breeding; Plant Breeding/Biotechnology; Plant Genetics and Genomics; Polymorphism, Single Nucleotide
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/s00122-015-2592-z

KEY MESSAGE : The white immature fruit color gene w was rapidly mapped to a 33.0-kb region to identify a valuable candidate gene that encodes peroxidase. The skin color of immature fruit is a crucial external trait of cucumbers, and white skin is shared by limited numbers of commercial cultivars. Herein, one BC₁ population and two F₂ segregating populations were constructed using four inbred parental lines (WD3 × B-2-2 and Q30 × Q24) to investigate the inheritance patterns and chromosomal locations of immature fruit color genes in cucumbers. Consequently, a single recessive gene, w, was identified that controls white immature fruit color. A total of 526 markers, which were derived from published genetic maps, two reference cucumber genomes (“9930” and GY14), and two parents (Q30 and Q24) for which whole-genome sequence information is available, were used to map the target gene w to a 33.0-kb region flanked by two SNP-based markers, ASPCR39262 and ASPCR39229, which are physically located at 39262450 and 39229482 of chromosome 3 (“9930” draft genome assembly), respectively. Gene prediction indicated that four potential genes were located in the target region. One gene that encodes peroxidase is likely to be a valuable candidate gene because quantitative real-time PCR revealed an eightfold difference in its transcriptional level, and several amino acid variations were found when the deduced amino acid sequence was aligned. A co-segregating marker was used synergistically to test its ability to predict the skin colors of 83 dark green/white germplasms, and the validity of its utility in marker-assisted selection was confirmed. Fine mapping of this locus will assist in cloning the gene and in marker-assisted breeding to develop dark green/white cucumber cultivars.