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

The posttranscriptional gene silencing of viral genes after viral infection.

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

Specific posttranscriptional gene inactivation ('silencing') both of viral gene(s), and host gene(s) homologous to the viral genes. This silencing is triggered by viral infection, and occurs through a specific decrease in the level of mRNA of both host and viral genes.

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an auxin stimulus.

The chemical reactions and pathways involving auxins, a group of plant hormones that regulate aspects of plant growth.

Any process that modulates the frequency, rate or extent of meristem organization.

The regionalization process in which differences in cell differentiation along the adaxial/abaxial are generated. Adaxial refers to being situated toward an axis of an anatomical structure. Abaxial refers to being situated away from an axis of an anatomical structure.

The process in which the anatomical structures of the leaf are generated and organized.

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of far red light stimulus. Far red light is electromagnetic radiation of wavelength 700-800nm. An example of this response is seen at the beginning of many plant species developmental stages. These include germination, and the point when cotyledon expansion is triggered. In certain species these processes take place in response to absorption of red light by the pigment molecule phytochrome, but the signal can be reversed by exposure to far red light. During the initial phase the phytochrome molecule is only present in the red light absorbing form, but on absorption of red light it changes to a far red light absorbing form, triggering progress through development. An immediate short period of exposure to far red light entirely returns the pigment to its initial state and prevents triggering of the developmental process. A thirty minute break between red and subsequent far red light exposure renders the red light effect irreversible, and development then occurs regardless of whether far red light exposure subsequently occurs.

Vascular tissue pattern formation as it occurs in the leaf of vascular plants.

The chemical reactions and pathways involving miRNA, microRNA, a class of single-stranded RNA molecules of about 21-23 nucleotides in length, which regulates gene expression.

The regionalization process within a leaf by which specific areas of cell differentiation are determined along a proximal/distal axis.

The inactivation of gene expression by a posttranscriptional mechanism.

The process in which relatively unspecialized cells, e.g. embryonic or regenerative cells, acquire specialized structural and/or functional features that characterize the cells, tissues, or organs of the mature organism or some other relatively stable phase of the organism's life history. Differentiation includes the processes involved in commitment of a cell to a specific fate and its subsequent development to the mature state.

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

Any process by which an organism retains a population of somatic stem cells, undifferentiated cells in the embryo or adult which can undergo unlimited division and give rise to cell types of the body other than those of the germ-line.

Downregulation of gene expression through the action of microRNAs (miRNAs), endogenous 21-24 nucleotide small RNAs processed from stem-loop RNA precursors (pre-miRNAs). Once incorporated into a RNA-induced silencing complex (RISC), miRNAs can downregulate gene expression by either of two posttranscriptional mechanisms: endolytic cleavage of the RNA (often mRNA) or mRNA translational repression, usually accompanied by poly-A tail shortening and subsequent degradation of the mRNA.

Downregulation of gene expression through the action of microRNAs (miRNAs), endogenous 21-24 nucleotide small RNAs processed from stem-loop RNA precursors (pre-miRNAs). Once incorporated into a RNA-induced silencing complex (RISC), miRNAs can downregulate gene expression by either of two posttranscriptional mechanisms: endolytic cleavage of the RNA (often mRNA) or mRNA translational repression, usually accompanied by poly-A tail shortening and subsequent degradation of the mRNA.

Innate immune responses are defense responses mediated by germline encoded components that directly recognize components of potential pathogens.

The process whose specific outcome is the progression of adventitious root over time, from its formation to the mature structure. Adventitious roots are post-embryonic roots that develop from the plant shoot.

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 modulates the frequency, rate or extent of shoot apical meristem development.

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.

A cell cycle process by which the cell nucleus divides as part of a meiotic cell cycle in the male germline.

A cell cycle process by which the cell nucleus divides as part of a meiotic cell cycle in the female germline.

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

The process whose specific outcome is the progression of the embryo sac over time, from its formation as the megaspore to the mature structure. The process begins when three of the four haploid megaspores disintegrate, and the fourth undergoes mitosis giving rise to a binucleate syncytial embryo sac. The two haploid nuclei migrate to the opposite poles of the embryo sac and then undergo two rounds of mitosis generating four haploid nuclei at each pole. One nucleus from each set of four migrates to the center of the cell. Cellularization occurs, resulting in an eight-nucleate seven-celled structure. This structure contains two synergid cells and an egg cell at the micropylar end, and three antipodal cells at the other end. A binucleate endosperm mother cell is formed at the center.

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a stimulus from a virus.

A response of a plant to a pathogenic agent that prevents the occurrence or spread of disease.

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

Any process involved in the transition of a plant from a juvenile phase of vegetative development to an adult phase of vegetative development.

Cleavage of double-stranded RNA to form trans-acting small interfering RNA molecules (siRNAs) of 21-23 nucleotides. ta-siRNAs arise from PolII genes and function like miRNAs to guide cleavage of target mRNAs.

The process in which an organism retains a population of shoot apical meristem cells, preventing the commitment of all stem cell progeny to a differentiated cell fate.

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

Cleavage of double-stranded RNA to form lsiRNA (long small interfering RNA), a class of siRNAs 30 to 40 nt in length. lsiRNAs are induced by pathogen infection or under specific growth conditions.

The process in which double-stranded RNAs silence cognate genes. Involves posttranscriptional gene inactivation ('silencing') both of transgenes or dsRNA introduced into a germline, and of the host gene(s) homologous to the transgenes or dsRNA. This silencing is triggered by the introduction of transgenes or double-stranded RNA (dsRNA), and can occur through a specific decrease in the level of mRNA, or by negative regulation of translation, of both host genes and transgenes.

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.

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

The process by which an organism or tissue maintains a population of stem cells of a single type. This can be achieved by a number of mechanisms: stem cell asymmetric division maintains stem cell numbers; stem cell symmetric division increases them; maintenance of a stem cell niche maintains the conditions for commitment to the stem cell fate for some types of stem cell; stem cells may arise de novo from other cell types.

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.

The modification of histone H3 by the removal of a methyl group from lysine at position 9 of the histone.

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

Downregulation of gene expression through the action of microRNAs (miRNAs), endogenous 21-24 nucleotide small RNAs processed from stem-loop RNA precursors (pre-miRNAs). Once incorporated into a RNA-induced silencing complex (RISC), miRNAs can downregulate gene expression by either of two posttranscriptional mechanisms: endolytic cleavage of the RNA (often mRNA) or mRNA translational repression, usually accompanied by poly-A tail shortening and subsequent degradation of the mRNA.

Any process that modulates the consistent predetermined time point at which an integrated living unit or organism progresses from an initial condition to a later condition and the rate at which this time point is reached.

The process whose specific outcome is the progression of the leaf over time, from its formation to the mature structure.

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.

The process whose specific outcome is the progression of the pollen grain over time, from its formation as the microspore to the mature structure.

The posttranscriptional gene silencing of viral genes after viral infection.

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.

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

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.

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

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

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.

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.

A region of a chromosome where nucleoli form during interphase, and where genes encoding the largest rRNA precursor transcript are tandemly arrayed.

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.

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.