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SR Lab/ Friday/ May 10, 2019/ 3.30 pm/ CHH methylation context the primary context for dictating developmental process of plant.
Category: Research
Posted by: bedineel



CHH methylation context: the primary context for dictating developmental process of plant?


In plant, DNA methylation occurs in CG, CHG and CHH sequence contexts involving distinct maintenance mechanisms. Methylation of DNA plays an important epigenetic mark in regulating many biological processes, but the exact role of methylation in gene expression is unknown. CHH methylation is highly enriched near genes (within 1kb upstream and downstream) and positively correlated with gene expression level in maize, while CG and CHG methylation contexts are concentrated in intergenic region. The importance of CHH context in plant development process is also illustrated by the studies on fruit ripening. CHH plays significant role in ripening of climacteric (tomato) and non-climacteric fruits (orange). In general, ripening of climacteric fruit reduces DNA methylation. The removal of DNA methylase significantly increased the mCHH and inhibits the process of ripening, but it has negligible effect on CG and CHG methylation. In similar fashion, ripening process of orange fruit is mostly contributed by methylation status of CHH compared to CG and CHG methylation context, although non-climacteric fruit ripening involve opposite mechanism of ripening climacteric fruit. Majority (~93%) of the hyper-Differentially Methylated Cytosines, which up-regulates or down-regulates the Differently Expressed Genes (DEGs) or non-DEGs, at mature fruit of orange occurred in CHH context. These studies seems to infer that the intricate relationships that exist between CHH context and cellular activities of gene dominate over the role of the other two methylation contexts in plant.



  1. Gent, J.I., Ellis, N.A., Guo, L., Harkess, A.E., Yao, Y., Zhang, X., and Dawe, R.K. (2013). CHH islands: de novo DNA methylation in near-gene chromatin regulation in maize. Genome Res. 23: 628–37.


  1. Huang, H., Liu, R., Niu, Q., Tang, K., Zhang, B., Zhang, H., Chen, K., Zhu, J.-K., and Lang, Z. (2019). Global increase in DNA methylation during orange fruit development and ripening. Proc. Natl. Acad. Sci. 116: 1430–1436.



  1. Lang, Z., Wang, Y., Tang, K., Tang, D., Datsenka, T., Cheng, J., Zhang, Y., Handa, A.K., and Zhu, J.-K. (2017). Critical roles of DNA demethylation in the activation of ripening-induced genes and inhibition of ripening-repressed genes in tomato fruit. Proc. Natl. Acad. Sci. 114: E4511–E4519.

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