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A Truncated F-Box Protein Confers the Dwarfism in Cucumber

Lin, Tao, Wang, Shenhao, Zhong, Yang, Gao, Dongli, Cui, Qingzhi, Chen, Huiming, Zhang, Zhonghua, Shen, Huolin, Weng, Yiqun, Huang, Sanwen
Journal of genetics and genomics 2016 v.43 no.4 pp. 223-226
DNA, F-box proteins, breeding, cucumbers, dwarf cultivars, dwarfing, genomics, growth traits, loci, mutants, phenotype, plant architecture, recessive genes, single nucleotide polymorphism
Dwarfism is an important plant architecture trait for cucumber breeding. In the present study, we identified a dwarf mutant 406M in cucumber which showed a shorter internode length as compared with its wild type. In a BC1F2 population from the cross of 406M with its wild type parental line 406, the segregation ratio fit 3:1 indicating the dwarf mutation was controlled by a single recessive gene. To identify the genetic basis of this mutation, we constructed a normal (N) and a mutant (M) bulk consisting 20 normal and dwarf plants, respectively. We re-sequenced the two DNA pools as well as the mutant line. SNPs between the two pools were identified, and SNP-index graphs were calculated and plotted. '(SNP-index) distribution identified 4 SNPs in cucumber chromosome 4 that were associated with the dwarf phenotype. Linkage analysis with the 4 SNPs in the BC1F2 population delimited the dwarf locus to a 2.04 Mb interval between the two markers dCAPS-SNP4G19847214 and dCAPS-SNP4G21882884. In this region, only dCAPS-SNP4G21398058 is co-segregating with the dwarfism phenotype, in which the cucumber gene Csa4G641640 encoding an F-Box protein was annotated. The SNP (C-to-T) mutation resulted in premature termination of the protein. Thus, genetic and genomic analysis pinpointed that the truncated F-Box Protein Csa4P641640 that was responsible for the dwarf phenotype in 406M.