PMID:27521428

Citation	Liu, H and Nonomura, KI (2016) A wide reprogramming of histone H3 modifications during male meiosis I in rice is dependent on the Argonaute protein MEL1. J. Cell. Sci. 129:3553-3561
Abstract	The roles of epigenetic mechanisms, including small-RNA-mediated silencing, in plant meiosis largely remain unclear, despite their importance in plant reproduction. This study unveiled that rice chromosomes are reprogrammed during the premeiosis-to-meiosis transition in pollen mother cells (PMCs). This large-scale meiotic chromosome reprogramming (LMR) continued throughout meiosis I, during which time H3K9 dimethylation (H3K9me2) was increased, and H3K9 acetylation and H3S10 phosphorylation were broadly decreased, with an accompanying immunostaining pattern shift of RNA polymerase II. LMR was dependent on the rice Argonaute protein, MEIOSIS ARRESTED AT LEPTOTENE1 (MEL1), which is specifically expressed in germ cells prior to meiosis, because LMR was severely diminished in mel1 mutant anthers. Pivotal meiotic events, such as pre-synaptic centromere association, DNA double-strand break initiation and synapsis of homologous chromosomes, were also disrupted in this mutant. Interestingly, and as opposed to the LMR loss in most chromosomal regions, aberrant meiotic protein loading and hypermethylation of H3K9 emerged on the nucleolar organizing region in the mel1 PMCs. These results suggest that MEL1 plays important roles in epigenetic LMR to promote faithful homologous recombination and synapsis during rice meiosis.
Links	PubMed Online version:10.1242/jcs.184937
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ORYSJ:MEL1		GO:1900111: positive regulation of histone H3-K9 dimethylation	ECO:0000315:		P		Fig. 3 Part F demonstrates a positive regulation of H3K9 dimethylation in regards to the wildtype MEL1 during pre-leptotene and post-leptotene meiotic phases. The mutant phenotype for MEL1 showed reduced levels of H3K9 dimethylation. The organism is Oryza sativa, and the gene is referred to as mel1 throughout the experiment and by Uniprot.	complete CACAO 12330
ORYSJ:MEL1		GO:2000616: negative regulation of histone H3-K9 acetylation	ECO:0000315:		P		Fig. 3 Part L demonstrates a negative regulation of H3-K9 acetylation, where the mel1 mutant showed relatively increased levels of H3-K9 acetylation between pre and post leptotene phases. The organism is Oryza sativa and the gene is referred to as mel1 by Uniprot and the experiment.	complete CACAO 12333
ORYSJ:MEL1		GO:0061866: negative regulation of histone H3-S10 phosphorylation	ECO:0000315:		P		Fig. 5 Part A-I demonstrates a negative regulation of H3-S10 phosphorylation, where the mel1 mutant showed relatively increased levels of H3-S10 phosphorylation between pre and post leptotene phases. The organism is Oryza sativa and the gene is referred to as mel1 by Uniprot and the experiment. A new term was requested: "negative regulation of histone H3-S10 phosphorylation" at https://github.com/geneontology/go-ontology/issues/13327	complete CACAO 12490
ORYSJ:MEL1		GO:1903343: positive regulation of meiotic DNA double-strand break formation	ECO:0000315:		P		Fig. 1 Part D shows a lack of double stand break formation during the meiotic leptotene state in a mel1 mutant. This is in comparison to the wild type cell in Fig. 1 Part A, and indicates a positive regulation of meiotic DNA double stand break formation. The protein is referred to as mel1 by both UniProt and the journal. The organism is Oryza sativa.	complete CACAO 12509

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