Four AUXIN RESPONSE FACTOR genes downregulated by microRNA167 are associated with growth and development in Oryza sativa

Abstract

MicroRNA167 (miR167), as a conserved miRNA, has been implicated in auxin signalling by regulating the expression of certain auxin response factor (ARF) genes to determine the plant developmental process. Among the 10 MIR167 genes of rice, the precursor structures derived from MIR167a, MIR167b and MIR167c produce miR167 with high efficiency. To explore the biological function of miR167 in rice, four of its predicted target genes, OsARF6, OsARF12, OsARF17 and OsARF25, were identified in vivo. Although the expression levels of miR167 and its target OsARFs did not show an obvious negative correlation, the enhanced miR167 level in transgenic rice overexpressing miR167 resulted in a substantial decrease in mRNA levels of the four OsARF genes. Moreover, the transgenic rice plants were small in stature with remarkably reduced tiller number. These results suggest that miR167 is important for the appropriate expression of at least four OsARFs, which mediate the auxin response, to contribute to the normal growth and development of rice.

miRNAs and lncRNAs in reproductive development

“…Although no direct evidence suggests a similar phenotype in crop plants, miR167 targeting of ARFs is a conserved mechanism in many species. For example, four ARFs (ARF6/12/17/25) are the targets of OsmiR167 in rice, and OsmiR167 overexpression leads to shorter plants with fewer tillers [25]. Importantly, OsmiR167 responds to exogenous auxin through its target gene, ARF8, which positively regulates OsGH3-2, a rice IAA-conjugating enzyme.…”

Osa‐miR167d facilitates infection of Magnaporthe oryzae in rice

“…In rice, miR167 is also involved in regulation of growth and development. Over‐expression of Osa‐miR167b results in reduced tiller number and small stature (Liu et al ). However, how Osa‐miR167d regulates immunity against rice blast fungus is largely unknown.…”

Elucidation of Abiotic Stress Signaling in Plants

“…The transcript abundance of OsPHR2 and its downstream targets miR399j, OsPHO2, miR827, SPX-MFS1, and SPXMFS2 ) are differentially regulated in arf12 mutants. Further ARF12 is targeted by miR167 in rice (Liu et al 2012c ). Also miR167 family members are differentially regulated under low nitrogen conditions in rice (Nischal et al 2012 ) suggesting the cross talk between nitrogen and phosphorus.…”