Quantitative Trait Transcripts Mapping Coupled with Expression Quantitative Trait Loci Mapping Reveal the Molecular Network Regulating the Apetalous Characteristic in Brassica napus L

The apetalous trait of rapeseed ( , AACC, 2 = 38) is important for breeding an ideal high-yield rapeseed with superior klendusity to . Currently, the molecular mechanism underlying the apetalous trait of rapeseed is unclear. In this study, 14 petal regulators genes were chosen as target genes (TGs), and the expression patterns of the 14 TGs in the AH population, containing 189 recombinant inbred lines derived from a cross between apetalous "APL01" and normal "Holly," were analyzed in two environments using qRT-PCR. Phenotypic data of petalous degree (PDgr) in the AH population were obtained from the two environments. Both quantitative trait transcript (QTT)-association mapping and expression QTL (eQTL) analyses of TGs expression levels were performed to reveal regulatory relationships among TGs and PDgr. QTT mapping for PDgr determined that ( ) was the major negative QTT associated with PDgr in both environments, suggesting that negatively regulates the petal development of line "APL01." The QTT mapping of expression levels showed that ( ) was positively associated with expression, indicating that acts as a positive regulator of expression. Similarly, QTT mapping for the remaining TGs identified 38 QTTs, associated with 13 TGs, and 31 QTTs, associated with 10 TGs, respectively, in the first and second environments. Additionally, eQTL analyses of TG expression levels showed that 12 and 11 unconditional eQTLs were detected in the first and second environment, respectively. Based on the QTTs and unconditional eQTLs detected, we presented a hypothetical molecular regulatory network in which 14 petal regulators potentially regulated the apetalous trait in "APL01" through the pathway. acts directly as the terminal signal integrator negatively regulating petal development in the pathway. These findings will aid in the understanding the molecular mechanism underlying the apetalous trait of rapeseed.