Genome-Wide DNA N6-Adenine Methylation in Sea Buckthorn (Hippophae rhamnoides Linn.) Fruit Development

Abstract As a new epigenetic mark, DNA N6-Adenine (6 mA) methylation plays an important role in a various biological process and has been reported in many prokaryotic organisms in recent years. However, the distribution patterns and functions of DNA 6 mA modification have been poor studied in non-model crops. In this study, we observed that the methylation ratio of 6 mA was about 0.016% in the sea buckthorn sea buckthorn (Hippophae rhamnoides Linn.) genome using mass spectrometry. Then, we firstly constructed a comprehensive 6 mA landscape in sea buckthorn genome using nanopore sequencing at single-base resolution. Distribution analysis suggested that 6 mA methylated sites were widely distributed in the sea buckthorn chromosomes, which similar with these in Arabidopsis and rice. Furthermore, reduced 6 mA DNA methylation is associated with different expression genes related fruit ripening process in sea buckthorn. Our results revealed that 6 mA DNA modification could be considered as an important epigenomic mark and contributes to fruit ripening process in plants.