摘要
The complexity of the epigenome landscape and transcriptional regulation is significantly increased during plant polyploidization,which drives genome evolution and contributes to the increased adaptability to diverse environments.However,a comprehensive epigenome map of Brassica napus is still unavailable.In this study,we performed integrative analysis of five histone modifications,RNA polymerase Ⅱ CCU-pancy,DNA methylation,and transcriptomes in two B.napus lines(2063A and B409),and established global maps of regulatory elements,chromatin states,and their dynamics for the whole genome(including the An and Cn subgenomes)in four tissue types(young leaf,flower bud,silique,and root)of these two lines.Approximately 65.8% of the genome was annotated with different epigenomic signals.Compared with the Cn subgenome,the An subgenome possesses a higher level of active epigenetic marks and lower level of repressive epigenetic marks.Genes from subgenome-unique regions contribute to the major differences between the An and Cn subgenomes.Asymmetric histone modifications between homeologous gene pairs reflect their biased expression patterns.We identified a novel bivalent chromatin state(with H3K4me1 and H3K27me3)in B.napus that is associated with tissue-specific gene expression.Furthermore,we observed that different types of duplicated genes have discrepant patterns of histone modification and DNA methylation levels.Collectively,our findings provide a valuable epigenetic resource for allopolyploid plants.
基金
This work was financially supported by the National Natural Science Foundation of China(31930032,31701163,31771422,and 31771402)
the National Key Research and Development Program of China(2016YFD0101300 and 2018YFC1604000)
the China Postdoctoral Science Foundation(2017M612479)
the Fundamental Research Funds for the Central Universities(2662018py033)
the open funds of the National Key Laboratory of Crop Genetic Improvement(ZK201906)
the Program for Modern Agricultural Industrial Technology System of China(grant no.CARS-12).
