Relationship between DNA methylation and gene expression in orchardgrass during vernalization. A, Distributions of methylation levels within gene bodies by different expression levels: none (FPKM < 1), low (1 < FPKM < lower quartile), medium (lower quartile < FPKM < upper quartile), and high (FPKM > upper quartile). “TSS” indicates the TSS, and “TTS” indicates the transcription termination sites. B, Expression profiles of methylated genes. Methylated genes were divided into five groups based on promoter and gene body region methylation levels: Group 1 (methylation levels < lower quintile), Group 2 (lower quintile < methylation levels < the second quintile), Group 3 (the third quintile < methylation levels < the fourth quintile), Group 4 (the fourth quintile < methylation levels < upper quintile), and Group 5 (methylation levels > upper quintile).