Epigenetic Control of Plant Development

Principal Investigator:

Description:

Compared to animals, plants show a remarkable plasticity that allows them to survive under different environmental conditions, compensating for their lack of mobility. To achieve this, plants need to be able to change pre-established cell fates. The epigenetic mechanisms that control chromatin organization are known to regulate cell differentiation both in animals and plants. Among these mechanisms, the Polycomb Group (PcG) machinery plays a crucial role in maintaining the stable repression of genes that are not required in a specific cell fate, thus, establishing a memory of differentiation. However, the high degree of cellular plasticity in plants suggests a more flexible PcG regulation. Unfortunately, this important regulatory mechanism is still largely unknown in plants; furthermore, how PcG function is induced, modulated, or repressed according to plant requirements remains a mystery.

PcG proteins form multiprotein complexes with different histone modifying activities. In animals, the two best-characterized PcG complexes are the PcG repressive complex 2 (PRC2) and PRC1 that possess histone 3 lysine 27 (H3K27) trimethyltransferase and histone 2A lysine 119 (H2AK119) E3 ubiquitin ligase activity, respectively. There is clear evidence that PRC2-mediated H3K27 trimethylation (H3K27me3) is indispensable for gene repression in plants; however, the implication of a plant PRC1 with H2A monoubiquitin ligase activity has just been recently revealed in our laboratory. Interestingly, several data suggest that the repression of genes involved in different cellular and developmental programs has different requirements for PRC1 subunit composition and H2Aub marking. An intriguing possibility could be that the composition of PRC1 determines the specificity and flexibility of repression, which could explain why plants are able to maintain a memory of differentiation and a high degree of plasticity, simultaneously. Our main goal is to unveil the different PcG regulatory mechanisms in plants and their biological functions.

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