Analysis of DNA methylation in different maize tissues
Yanli Lu, Tingzhao Rong, Moju Cao Maize Research Institute of Sichuan Agriculture University/Key Laboratory of Crop Genetic Resource and Improvement, Ministry of Education, Ya’an, 625014, China
DNA methylation plays an important role in gene expression regulation during biological development and tissue differentiation in plants. This study adopted methylation-sensitive Amplified fragment length polymorphism (AFLP) to compare the levels of DNA cyto- sine methylation at CCGG sites in tassel, bracteal leaf, and ear leaf from maize inbred lines, 18 White and 18 Red, respectively, and also examined specific methylation patterns of the three tissues. Significant differences in cytosine methylation level among the three tissues and the same changing tendency in two inbred lines were detected. Both MSAP (methylation sensitive amplification polymorphism) ratio and full methylation level were the highest in bracteal leaf, and the lowest in tassel. Meanwhile, different methylation levels were ob- served in the same tissue from the inbred lines, 18 White and 18 Red. Full methylation of internal cytosine was the dominant type in the maize genome. The differential methylation patterns in the three tissues were observed. In addition, sequencing of nine differentially me- thylated fragments and the subsequent blast search revealed that the cytosine methylated 5′-CCGG-3′sequences were distributed in re- peating sequences, in the coding and noncoding regions. Southern hybridization was used to verify the methylation polymorphism. These results clearly demonstrated the power of the MSAP technique for large-scale DNA methylation detection in the maize genome, and the complexity of DNA methylation change during plant growth and development. The different methylation levels may be related to specific gene expression in various tissues.