“Epigentic Memory” in Plants; Plants Are Able to “Forget” Memory of Earlier Winter So As to Still Flower at Correct Time in Following Year

A study published online on May 11, 2020 in Nature Cell Biology reveals more information on the capacity of plants, identified as “epigenetic memory,” which allows recording important information to, for example, remember prolonged cold in the winter to ensure they flower at the right time during the spring. As soon as they produce seeds, this information is "erased" from memory so they don't bloom too early the following winter. Although they do it differently than humans, plants also have memories. This so-called "epigenetic memory" occurs by modifying specialized proteins called histones, which are important for packaging and indexing DNA in the cell. One such histone modification, called H3K27me3, tends to mark genes that are turned off. In the case of flowering, cold conditions cause H3K27me3 to accumulate at genes that control flowering. The Nature Cell Biology article is titled “Targeted Reprogramming of H3k27me3 Resets Epigenetic Memory in Plant Paternal Chromatin.” Previous work, from the laboratory of Jörg Becker (https://gulbenkian.pt/ciencia/research/research-groups/plant-genomics/), PhD, Principal Investigator at the Instituto Gulbenkian de Ciência in Portugal, has shown how H3K27me3 is faithfully transmitted from cell to cell so that in the spring, plants will remember that it was cold and that winter is over, allowing them to flower at the right time. But just as importantly, once they've flowered and made seeds, the seeds need to forget this “memory” of the cold so that they do not flower too soon once winter comes around again. Because H3K27me3 is faithfully copied from cell to cell, how do plants go about forgetting this memory in seeds?
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