CpG methylated ribosomal RNA genes in relation to wing polymorphism in the rice pest Sogatella furcifera

• Two differentially methylated DNA fragments related with wing phenotype were found.
• One fragment was highly similar to the 18S ribosomal RNA genes.
• Another fragment was homologous to the 28S ribosomal RNA gene.
• DNA methylation of ribosomal RNA genes may be related to wing phenotype variations.

Sogatella furcifera is a major rice pest that exhibits wing dimorphism. The methylation-sensitive representational difference analysis (MS-RDA) is widely used in plants and some animals to identify methylation differences in genomic DNA regions. However the method has been applied to insects very less. The objective of the current research was to monitor differential cytosine methylations at CCGG sequences in macropterous and brachypterous adults of female S. furcifera to determine the association between gene methylation and wing phenotypes using MS-RDA. After the second subtractive hybridization, two differentially methylated DNA fragments were obtained. These DNA fragments were then cloned into the pGEM-T vector and sequenced. One fragment from the positive hybridization was 464 bp, and highly similar to the 18S ribosomal RNA (rRNA) genes from some animals. Another fragment from the reverse hybridization was 453 bp, and homologous to the 28S rRNA gene of S. furcifera with a similarity rate as high as 99%. These results provide potential evidence that DNA methylation of rRNA genes may be related to wing phenotype variations in S. furcifera, and will facilitate future studies on the epigenetic mechanisms of insect wing polymorphism.

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