Fine-mapping and candidate gene analysis of qFL-c10-1 controlling fiber length in upland cotton (Gossypium hirsutum L.).

KEY MESSAGE: A fiber length QTL, qFL-c10-1, was fine-mapped to a 96.5-kb region containing one gene that has not been characterized in plants. Fiber length is an important component of cotton fiber quality, which is associated with other quality properties such as fiber strength, fiber maturity, and fineness. In our previous studies, a stable QTL qFL-c10-1 controlling fiber length had been identified on chromosome A10 in an upland cotton recombinant inbred line (RIL) population from a cross between Jimian5 and DH962. To fine-map qFL-c10-1, an F2 population with 1081 individual plants from a cross between a recombinant line DJ61 and Jimian5 was established. Using linkage analysis and progeny recombination experiment, qFL-c10-1 was mapped into a 96.5-kb genomic region that just contained one proper transcript Ghir_A10G022020 (described as GhFL10), an undescribed gene in plants. One 214-bp deletion was identified in the promoter region of DJ61 compared with Jimian5. Quantitative real-time PCR (qRT-PCR) and comparative analysis of parental sequences suggested that GhFL10 was the most promising candidate gene for qFL-c10-1. According to RNA-seq, yeast two-hybrid assay and bimolecular fluorescence complementation (BiFC), we speculate that GhFL10 interacts with NF-YA transcription factors to negatively regulate fiber elongation.