title: The expanding world of small RNAs in plants.
abstract: Plant genomes encode various small RNAs that function in distinct, yet overlapping, genetic and epigenetic silencing pathways. However, the abundance and diversity of small-RNA classes varies among plant species, suggesting coevolution between environmental adaptations and gene-silencing mechanisms. Biogenesis of small RNAs in plants is well understood, but we are just beginning to uncover their intricate regulation and activity. Here, we discuss the biogenesis of plant small RNAs, such as microRNAs, secondary siRNAs and heterochromatic siRNAs, and their diverse cellular and developmental functions, including in reproductive transitions, genomic imprinting and paramutation. We also discuss the diversification of small-RNA-directed silencing pathways through the expansion of RNA-dependent RNA polymerases, DICER proteins and ARGONAUTE proteins.
authors.affiliation: Howard Hughes Medical Institute and Gordon and Betty Moore Foundation, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA.
authors.forename: Filipe
authors.initials: F
authors.lastname: Borges
authors.affiliation: Howard Hughes Medical Institute and Gordon and Betty Moore Foundation, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Martienssen
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D060565:Argonaute Proteins / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012326:RNA Splicing / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism*; D020733:RNA, Small Cytoplasmic / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism; D043244:Ribonuclease III / Q000378:metabolism
chemical_list: D060565:Argonaute Proteins; D035683:MicroRNAs; D018749:RNA, Plant; D020733:RNA, Small Cytoplasmic; D034741:RNA, Small Interfering; D012324:RNA-Dependent RNA Polymerase; D043244:Ribonuclease III