Analysis of DNA cytosine methylation patterns in maize hybrids and their parents

Abstract

In order to better understand the molecular basis of heterosis in maize, the methylation-sensitive amplification polymorphism method was used to estimate patterns of cytosine methylation in seedling roots and leaves and 15-d postfertilization embryo and endosperm tissues of hybrids and their parental lines Zheng58 and Chang7-2. In all tissues, total relative methylation levels in the hybrids were lower than corresponding mid-parent values, with a higher number of demethylation events inferred for the hybrids. The trend of reduced methylation and increased demethylation in the hybrids relative to their parents may allow de-repression and possibly the expression of various genes associated with a hybrid phenotypic variation. To further investigate observed methylation pattern changes, we sequenced 50 differentially displayed DNA fragments. The BLAST analysis revealed that 13 fragments shared similarity with known functional proteins in maize or other plant species including proteins related to metabolism, transposons/retrotransposons, development, stress response, and signal transduction. The genes associated with these proteins may thus contribute significantly to maize hybrid vigour.