To enrich our knowledge about gene network of fatty acid biosynthesis in cottonseed, we conducted comparative transcriptome to reveal the differences in gene expression between Gossypium hirsutum and Gossypium barbadense during cottonseed development. The prolonged expression period and increased expression abundance of oil-related genes are the main reasons for producing high seed oil content (SOC) in G. barbadense, which manifested as the bias of homeologous gene expression in Dt-subgenome after 25 day postanthesis (DPA). The dynamic expression profile showed that SAD6 and FATA are more important for oil biosynthesis in G. barbadense than that in G. hirsutum. Three key transcription factors, WRI1, NF-YB6 and DPBF2, showed their elite roles in regulating seed oil in cotton. We observed that sequence variations in the promoter region of BCCP2 genes might contribute to its divergence in expression level between the two species. Based on the quantitative trait loci (QTL) information of the seed oil content and utilizing additional G. barbadense introgression lines (ILs), we propose 21 candidate genes on the basis of their differential expression level, of which the GbSWEET and the GbACBP6 showed the potential functional to improve the oil content. Taken together, studying the different expression of oil-related genes and their genetic regulation mechanisms between G. hirsutum and G. barbadense provide new insights to understanding the mechanism of fatty acid biosynthesis network and fatty acid genetic improving breeding in cotton.

中文翻译：

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栽培四倍体棉花油脂积累基因网络及关键基因的全球调查

为了丰富我们对棉籽脂肪酸生物合成基因网络的了解，我们进行了比较转录组研究，以揭示棉籽发育过程中陆地棉和巴巴多棉之间基因表达的差异。油相关基因表达期延长和表达丰度增加是导致G. barbadense种子含油量（SOC）高的主要原因，表现为花后25天后Dt亚基因组同源基因表达的偏向性（DPA） ）。动态表达谱表明SAD6和FATA对G. barbadense油生物合成的重要性高于G. hirsutum. 三个关键转录因子WRI1、NF-YB6和DPBF2显示出它们在调节棉花籽油中的重要作用。我们观察到BCCP2基因启动子区域的序列变异可能导致两个物种之间表达水平的差异。基于种子含油量的数量性状位点 (QTL) 信息并利用额外的G. barbadense基因渗入系 (IL)，我们根据其差异表达水平提出了 21 个候选基因，其中GbSWEET和GbACBP6显示出提高含油量的潜在功能。总之，研究G. hirsutum和G. barbadense之间油相关基因的不同表达及其遗传调控机制，为理解棉花脂肪酸生物合成网络机制和脂肪酸遗传改良育种提供了新的见解。