title: Phased, secondary, small interfering RNAs in posttranscriptional regulatory networks.
abstract: Plant genomes are the source of large numbers of small RNAs, generated via a variety of genetically separable pathways. Several of these pathways converge in the production of phased, secondary, small interfering RNAs (phasiRNAs), originally designated as trans-acting small interfering RNAs or tasiRNAs. PhasiRNA biogenesis requires the involvement of microRNAs as well as the cellular machinery for the production of siRNAs. PhasiRNAs in Arabidopsis thaliana have been well described for their ability to function in trans to suppress target transcript levels. Plant genomic data from an expanding set of species have demonstrated that Arabidopsis is relatively sparing in its use of phasiRNAs, while other genomes contain hundreds or even thousands of phasiRNA-generating loci. In the dicots, targets of those phasiRNAs include several large or conserved families of genes, such as those encoding disease resistance proteins or transcription factors. Suppression of nucleotide-binding, leucine-rich repeat (NB-LRR) disease resistance genes by small RNAs is particularly unusual because of a high level of redundancy. In this review, we discuss plant phasiRNAs and the possible mechanistic significance of phasiRNA-based regulation of the NB-LRRs.
authors.affiliation: Department of Plant and Soil Sciences, Delaware Biotechnology Institute, University of Delaware, Newark, DE 19711, USA.
authors.forename: Qili
authors.initials: Q
authors.lastname: Fei
authors.forename: Rui
authors.initials: R
authors.lastname: Xia
authors.forename: Blake C
authors.initials: BC
authors.lastname: Meyers
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D018506:Gene Expression Regulation, Plant; D000090263:Leucine-Rich Repeat Proteins; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010944:Plants / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D018749:RNA, Plant / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism
chemical_list: D000090263:Leucine-Rich Repeat Proteins; D011506:Proteins; D018749:RNA, Plant; D034741:RNA, Small Interfering