Occurrence of cpg islands in differentially methylated Loci in Sesamum indicum L. upon phytoplasma infection

Abstract

Phytoplasmas are cell wall-less bacteria that inhabit the phloem, transmitted by sap sucking insects and associated with diseases in numerous plants including economically important taxa. Phytoplasmas are associated with the serious disease of sesame known as phyllody in nearly all growing countries. Currently, the disease is a significant threat to the production in the most important sesame-producing regions of the world. Symptoms of sesame phyllody include shoot proliferation, virescence, foliar yellowing, shortened internodes, small leaves, abnormal floral organs, generalized stunting, and phloem necrosis. Studies on changes in the levels of gene expression in response to phytoplasma infection are almost lacking in sesame. DNA methylation is a conserved epigenetic mark that regulates multiple processes, and its disruption can lead to developmental abnormalities. The CpG sites are DNA sequences where a cytosine followed by a guanine is often methylated to form 5-methylcytosines and are known to regulate gene expression through transcriptional silencing. In the present study, seven loci from sesame genome were chosen based on their role in development or defence that were found to be differentially methylated using whole genome bisulfite sequencing followed by in-silico analysis using Meth Primer online tool. All the loci were found to consist of one or more CpG islands. CpG island specific primers were designed to confirm their presence. Expected amplicons were obtained in both healthy and phyllody infected sesame plants.