Genomic imprinted genes in reciprocal hybrid endosperm of Brassica napus

AbstractBackgroundGenomic imprinting results in the expression of parent-of-origin-specific alleles in the offspring.Brassica napusis an oil crop with research values in polyploidization. Identification of imprinted genes inB. napuswill enrich the knowledge of genomic imprinting in dicotyledon plants.ResultsIn this study, we performed reciprocal crosses betweenB. napusL. cultivars Yangyou 6 (Y6) and Zhongshuang 11 (ZS11) to collect endosperm at 20 and 25 days after pollination (DAP) for RNA-seq. In total, we identified 297 imprinted genes, including 283 maternal expressed genes (MEGs) and 14 paternal expressed genes (PEGs) according to the SNPs between Y6 and ZS11. Only 36 genes (35 MEGs and 1 PEG) were continuously imprinted in 20 and 25 DAP endosperm. We found 15, 2, 5, 3, 10, and 25 imprinted genes in this study were also imprinted inArabidopsis, rice, castor bean, maize,B. rapa, and otherB. napuslines, respectively. Only 26 imprinted genes were specifically expressed in endosperm, while other genes were also expressed in root, stem, leaf and flower bud ofB. napus. A total of 109 imprinted genes were clustered on rapeseed chromosomes. We found the LTR/Copia transposable elements (TEs) were most enriched in both upstream and downstream of the imprinted genes, and the TEs enriched around imprinted genes were more than non-imprinted genes. Moreover, the expression of 5AGLsand 6 pectin-related genes in hybrid endosperm were significantly changed comparing with that in parent endosperm.ConclusionThis research provided a comprehensive identification of imprinted genes inB. napus, and enriched the gene imprinting in dicotyledon plants, which would be useful in further researches on how gene imprinting regulates seed development.