Reactions triggered in response to the presence of a virus that act to protect the cell or organism.

The covalent transfer of a methyl group to either N-6 of adenine or C-5 or N-4 of cytosine.

The process in which a virus effects a change in the structure or processes of its host organism.

Cleavage of double-stranded RNA to form small interfering RNA molecules (siRNAs) of 21-23 nucleotides, in the context of RNA interference.

Cleavage of double-stranded RNA to form small interfering RNA molecules (siRNAs) of 21-23 nucleotides, in the context of chromatin silencing by small RNA.

Any process that stops, prevents, or reduces the frequency, rate or extent of transcription mediated by RNA polymerase II.

Repression of transcription by altering the structure of chromatin, e.g. by conversion of large regions of DNA into an inaccessible state often called heterochromatin.

Repression of transcription by altering the structure of chromatin, e.g. by conversion of large regions of DNA into an inaccessible state often called heterochromatin.

The process in which the megasporocyte undergoes meiosis, giving rise to four haploid megaspores in the nucellus.

A response of an organism to a bacterium that prevents the occurrence or spread of disease.

Any process that decreases the frequency, rate or extent of transposition. Transposition results in the movement of discrete segments of DNA between nonhomologous sites.

Any process carried out at the cellular level that results in either long-term transcriptional repression via action on chromatin structure or RNA mediated, post-transcriptional repression of gene expression.

Repression of transcription of centromeric DNA by altering the structure of chromatin.

Repression of transcription by conversion of large regions of DNA into heterochromatin, directed by small RNAs sharing sequence identity to the repressed region.

Repression of transcription by conversion of large regions of DNA into heterochromatin, directed by small RNAs sharing sequence identity to the repressed region.

The process in which double-stranded siRNA molecules are converted to single-stranded siRNAs; required for the formation of a mature RITS complex during RNA interference.

A process in which the RNAi machinery mediates the degradation of nascent transcripts in association with chromatin.

Reactions triggered in response to the presence of a bacterium that act to protect the cell or organism.

The process whose specific outcome is the progression of the ovule over time, from its formation to the mature structure. The ovule is the structure in seed plants enclosing the female gametophyte, and is composed of the nucellus, one or two integuments, and the funiculus; it develops into the seed.

The modification of histone H3 by addition of one or more methyl groups to lysine at position 9 of the histone.

Any process that modulates the frequency, rate or extent of the covalent addition of a methyl group to the lysine at position 9 of histone H3.

Reactions triggered in response to the presence of a virus that act to protect the cell or organism.

Any process that results in the specification, formation or maintenance of the physical structure of eukaryotic heterochromatin and contributes to chromatin silencing.

The process in which an siRNA-associated RNA-induced silencing complex (siRISC) associates with nascent transcripts and RNA polymerase to induce the formation of heterochromatin.

The chemical reactions and pathways occurring in the nucleus and resulting in the breakdown of a noncoding RNA (ncRNA) molecule, initiated by the enzymatic addition of a sequence of adenylyl residues (polyadenylation) at the 3' end the target ncRNA.

An epigenetic RNA-based gene silencing process first elucidated in plants whereby 24-nt small interfering RNAs (siRNAs) guide DNA methyltransferases to the siRNA-generating genomic loci and other loci that are homologous to the siRNAs for de novo DNA methylation. In general this process consists of three phases: biogenesis of siRNAs, scaffold RNA production, and the formation of the guiding complex that recruits de novo DNA methyltransferases to the target loci.

The chemical reactions and pathways involving the hydrolysis of internal 3',5'-phosphodiester bonds in one or two strands of ribonucleotides.

The process in which a relatively unspecialized cell acquires the specialized features of a megasporocyte.

A membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated. In most cells, the nucleus contains all of the cell's chromosomes except the organellar chromosomes, and is the site of RNA synthesis and processing. In some species, or in specialized cell types, RNA metabolism or DNA replication may be absent.

That part of the nuclear content other than the chromosomes or the nucleolus.

The dispersed less dense form of chromatin in the interphase nucleus. It exists in at least two forms, a some being in the form of transcriptionally active chromatin which is the least condensed, while the rest is inactive euchromatin which is more condensed than active chromatin but less condensed than heterochromatin.

A small, dense body one or more of which are present in the nucleus of eukaryotic cells. It is rich in RNA and protein, is not bounded by a limiting membrane, and is not seen during mitosis. Its prime function is the transcription of the nucleolar DNA into 45S ribosomal-precursor RNA, the processing of this RNA into 5.8S, 18S, and 28S components of ribosomal RNA, and the association of these components with 5S RNA and proteins synthesized outside the nucleolus. This association results in the formation of ribonucleoprotein precursors; these pass into the cytoplasm and mature into the 40S and 60S subunits of the ribosome.

All of the contents of a cell excluding the plasma membrane and nucleus, but including other subcellular structures.

The part of the cytoplasm that does not contain organelles but which does contain other particulate matter, such as protein complexes.

The part of the cytoplasm that does not contain organelles but which does contain other particulate matter, such as protein complexes.

A class of nuclear body, first seen after silver staining by Ramon y Cajal in 1903, enriched in small nuclear ribonucleoproteins, and certain general RNA polymerase II transcription factors; ultrastructurally, they appear as a tangle of coiled, electron-dense threads roughly 0.5 micrometers in diameter; involved in aspects of snRNP biogenesis; the protein coilin serves as a marker for Cajal bodies. Some argue that Cajal bodies are the sites for preassembly of transcriptosomes, unitary particles involved in transcription and processing of RNA.

A protein complex required for heterochromatin assembly; contains an Argonaute homolog, a chromodomain protein, and at least one additional protein; named for RNA-induced initiation of transcriptional gene silencing.

Nuclear heterochromatin that is located adjacent to the CENP-A rich centromere 'central core' and characterized by the modified histone H3K9me3.

Heterochromatic regions of the chromosome found at silenced mating-type loci.

A ribonucleoprotein complex that contains members of the Argonaute family of proteins, additional protein subunits, and duplex siRNA; required for heterochromatin assembly and siRNA generation. Possibly involved in the conversion of ds siRNA to ss siRNA.

Heterochromatic regions of the chromosome found at the subtelomeric regions of a chromosome in the nucleus.