DNA methylation polymorphism in a set of elite maize inbred lines revealed by methylation-sensitive ISSR analysis

DNA methylation polymorphism among nine elite maize inbred lines was assessed by inter-simple sequence repeat (ISSR) fingerprinting on intact DNA and DNA digested by either of a pair of methylation-sensitive isoschizomers, Hpa II and Msp I. It was found that, along with distinct genetic differentiation, extensive DNA methylation polymorphism exists among the nine inbred lines. The line-specific methylation patterns are homogeneous within each line, indicating their usefulness as molecular markers for cultivar identification. DNA sequences underlying the DNA methylation variations include a high proportion of coding genes. Cluster analysis, however, indicates the existence of incongruence between DNA methylation polymorphism and known-pedigree of the maize inbred lines.