title: Characterization of phosphorus-regulated miR399 and miR827 and their isomirs in barley under phosphorus-sufficient and phosphorus-deficient conditions.
abstract: BACKGROUND
  miR399 and miR827 are both involved in conserved phosphorus (P) deficiency signalling pathways. miR399 targets the PHO2 gene encoding E2 enzyme that negatively regulates phosphate uptake and root-to-shoot allocation, while miR827 targets SPX-domain-containing genes that negatively regulate other P-responsive genes. However, the response of miR399 and miR827 to P conditions in barley has not been investigated.
  
  
  RESULTS
  In this study, we investigated the expression profiles of miR399 and miR827 in barley (Hordeum vulagre L.) under P-deficient and P-sufficient conditions. We identified 10 members of the miR399 family and one miR827 gene in barley, all of which were significantly up-regulated under deficient P. In addition, we found many isomirs of the miR399 family and miR827, most of which were also significantly up-regulated under deficient P. Several isomirs of miR399 members were found to be able to cleave their predicted targets in vivo. Surprisingly, a few small RNAs (sRNAs) derived from the single-stranded loops of the hairpin structures of MIR399b and MIR399e-1 were also found to be able to cleave their predicted targets in vivo. Many antisense sRNAs of miR399 and a few for miR827 were also detected, but they did not seem to be regulated by P. Intriguingly, the lowest expressed member, hvu-miR399k, had four-fold more antisense sRNAs than sense sRNAs, and furthermore under P sufficiency, the antisense sRNAs are more frequent than the sense sRNAs. We identified a potential regulatory network among miR399, its target HvPHO2 and target mimics HvIPS1 and HvIPS2 in barley under P-deficient and P-sufficient conditions.
  
  
  CONCLUSIONS
  Our data provide an important insight into the mechanistic regulation and function of miR399, miR827 and their isomirs in barley under different P conditions.
authors: Michael
authors: M
authors: Hackenberg
authors: Australian Centre for Plant Functional Genomics, The University of Adelaide, Urrbrae, South Australia 5064, Australia. bujun.shi@adelaide.edu.au.
authors: Bu-Jun
authors: BJ
authors: Shi
authors: Perry
authors: P
authors: Gustafson
authors: Peter
authors: P
authors: Langridge
mesh_terms: D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000235:genetics* / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics*; D010758:Phosphorus / Q000172:deficiency* / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics*
chemical_list: D035683:MicroRNAs; D018749:RNA, Plant; D010758:Phosphorus