The Embryogenic Callus Inducation And Plant Regeneration In Rice Tissue Culture Are Respectively Accompanied By Decrease In Cytosine Methylation And Restoration

By methylation-sensitive amplified polymorphism (MSAP) analysis, we globally assessed the extent and pattern of cytosine methylation in rice cultivar oryza sativa L. japonica cv. taipei 309 during dedifferentiation and regeneration. Two kinds of main variations were found: (i) overall cytosine methylation level decreased in embryogenic calli by tissue culture or 5-azaC treatment, while the level recovered partially after regeneration; (ii) cytosine DNA hemi-methylation level increased in embryogenic calli during tissue culture or drug treatment and the status remained after regeneration; (iii) by site specific analysis, the main variation is increasing bands from seed plant to cultured calli and decreasing bands from cultured calli to shoot regenerants. These results suggest that embryogenesis maybe need a relatively low level of cytosine DNA methylation, while for differentiation from embryogenic calli, a higher methylation level is necessary. What is most importantly, some tissue or developmental stage specific methylation sites were also found and corresponding amplified bands were sequenced, blast results showed part of them have homologues with known genes, and some specially methylated loci in different tissues located in promoter regions of genes.