qOil-3, a major QTL identification for oil content in cottonseed across genomes and its candidate gene analysis
2020
Cotton (Gossypium spp.) is an important resource of fiber and oil. Oil content in cottonseed is getting more and more attention. In present study, a genetic map with 388 molecular markers was constructed to identify QTL for oil content in cottonseed. An immortal double backcross population including 376 individuals was generated from the crosses between HS46, MAR-188 and their 188 RILs. A total of 8 QTL associated with oil content were identified. One of them, qOil-3 for oil content explaining a collective phenotypic variance of 5.24 % was detected in four different environments of two years. It has only significant additive main effect from embryo genome and maternal additive main effect, implying high value in genetic breeding. The position for qOil-3 with the internal of approximately 2 cM on chromosome A03 overlapped the position of QTL for oil content by bulked segregant analysis and whole-genome re-sequencing method. Based on the sequence and gene expression analysis between two parents including HS46 and MAR-188 as well as DY-pool and GY-pool, two candidate genes Gh_A03G0701 and Gh_A03G0699 at the overlaps of qOil-3 were screened. Gh_A03G0701 was predicted to encode the 3-ketoacyl-CoA enzyme that is related to synthesis of oil. Two SNPs occurred in the exons of this gene between the extreme oil content pool, as well as between the parents HS46 and MAR-188. Gh_A03G0699 has four mutation loci in downstream sequence between HS46 and MAR-188 as well as GY-pool and DY-pool. Both candidate genes might serve as the foundation for further studies of the molecular mechanisms in natural variation of oil content and the genetic breeding for higher oil content in cottonseed.
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