Jitendra P. Khurana

Friday Seminar by Ringyao Jajo


SR Lab/ Friday/ January 17, 2019/ 3.30 pm/ DME/ROS1a: Epigenetic Reprogrammer of Plant Reproductive Cells
Category: Research
Posted by: bedineel

 

DME/ROS1a: Epigenetic Reprogrammer of Plant Reproductive Cells

 

Reproduction is the fundamental task of all living organisms. Sexual reproduction of flowering plant is carried out by multicellular gametophytes that arise through mitosis from haploid meiotic spores. Development of an embryo from fused haploid spores require regulation of gene expression and it involved extensive epigenetic reprogramming, especially in the endosperm. The DEMETER (DME) DNA glycosylase is involved in reconfiguration of the endosperm methylation landscape in Arabidopsis. This reprogramming step  is initiated in central cell. DME also initiates localized DNA demethylation in vegetative cells. The demethylated cells can be partially restored to a methylation level comparable to other tissues if the DME gene is mutated, indicating the strong role of the DNA glycosylase in regulating the epigenetic dynamics of plant reproductive cells. In a similar fashion in rice, REPRESSOR OF SILENCING 1a (ROS1a) gene, which is closely related to DME, is found to be associated with epigenetic reprogramming in reproductive cell. Genome-wide analysis of DNA methylation in wild-type and ros1a-mutant showed that vegetative cell genome is locally hypomethylated compared to sperm cell. Moreover, in central cell many ROS1a target sequences in the vegetative cells were hypomethylated. The studies also showed that reproductive cell genome undergo dynamic DNA methylation reprogramming after cell fusion and that the glycosylase-mediated reprogramming processes are well conserved, especially in two distantly diverged Arabidopsis and rice.
 

References:

  1. Hsieh T-F, et al. (2009) Genome-wide demethylation of Arabidopsis endosperm. Science 324(933):1451-1454.
  2. Park K, et al. (2016) DNA demethylation is initiated in the central cells of Arabidopsis and rice. Proc Natl Acad Sci USA 113:15138-15143.
  3. Kim M. Y, et al (2019) DNA demethylation by ROS1a in rice vegetative cells promotes methylation in sperm. Proc Natl Acad Sci USA 116:9652-9657.