Water Stress Responsive Differential Methylation of Organellar Genomes of <i>Zea mays</i> Z59

DNA methylation is an important epigenetic change\r\naffecting gene expression in plants in both normal and stress conditions. The\r\norganelles, mitochondria and chloroplast play a significant role in sensing and\r\ninitiating stress response. In this study, we report the methylation pattern in\r\nchloroplast and mitochondrial genomes in irrigated and water stressed\r\nconditions and its relationship with gene expression of a drought tolerant Zea mays cultivar, Z59. Whole genome bisulfite sequencing was done to analyze the\r\npattern of methylation in both the conditions. Mapping of bisulfite reads to\r\nB73 reference of mitochondrial and chloroplast genomes showed hypomethylation\r\nin water stressed plants when compared to irrigated plants. Sliding window\r\napproach to the methylation count data showed highest peak at 419,800 to\r\n420,800 bp region in mitochondria and at 36,900 to 37,900 bp region in\r\nchloroplast genomes in both samples. Annotation of the methylated genomes\r\nshowed that, genes related to photosystem I \u0026 II in chloroplast and nad4\r\ngene in mitochondria were hypo methylated in the water stressed sample. RNA-seq\r\nanalysis of transcriptomics reads mapped to the same\r\nreference showed regulation of rps3, rps2A, ccmFC, atp1 and many\r\nuncharacterized genes in mitochondria and psbA, psbD, psbc, psaA, and atpA,\r\ngenes in chloroplast.