Molecular phylogeny of miR390-guided trans-acting siRNA genes (TAS3) in the grass family
Trans-acting siRNAs (tasiRNAs) are a plant-specific class of 21-nt endogenous siRNAs that function as miRNA-like posttranscriptional negative regulators. Several tasiRNA loci (known as TAS genes) have been characterized to date in rice and Arabidopsis. The TAS3 family is distinguished from other TAS loci by the dual miR390 complementary sites flanking the tasiRNA region and its dependence on ARGONAUTE7. In this study, 55 putative TAS3 genes were identified by database mining and PCR amplification from the grass family. Phylogenetic analysis indicated that several genome/gene duplication events have been involved in the expansion of TAS3 genes while some TAS3 genes might have been lost during evolution of the grass family. The role of miR390 target genes in the origin of TAS3 genes are discussed.
KeywordsTrans-acting siRNA (tasiRNA) TAS3 Poaceae Evolution miR390
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