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Open Access Research article

Over-expression of microRNA171 affects phase transitions and floral meristem determinancy in barley

Julien Curaba1, Mark Talbot1, Zhongyi Li1 and Chris Helliwell2*

Author affiliations

1 CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia

2 Current address: School of Agriculture and Food Systems, University of Melbourne, Parkville, Victoria, 3010, Australia

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Citation and License

BMC Plant Biology 2013, 13:6  doi:10.1186/1471-2229-13-6

Published: 7 January 2013

Abstract

Background

The transitions from juvenile to adult and adult to reproductive phases of growth are important stages in the life cycle of plants. The regulators of these transitions include miRNAs, in particular miR156 and miR172 which are part of a regulatory module conserved across the angiosperms. In Arabidopsis miR171 represses differentiation of axillary meristems by repressing expression of SCARECROW-LIKE(SCL) transcription factors, however the role of miR171 has not been examined in other plants.

Results

To investigate the roles of mir171 and its target genes in a monocot, the Hvu pri-miR171a was over-expressed in barley (Hordeum vulgare L. cv. Golden promise) leading to reduced expression of at least one HvSCL gene. The resulting transgenic plants displayed a pleiotropic phenotype which included branching defects, an increased number of short vegetative phytomers and late flowering. These phenotypes appear to be the consequence of changes in the organisation of the shoot meristem. In addition, the data show that miR171 over-expression alters the vegetative to reproductive phase transition by activating the miR156 pathway and repressing the expression of the TRD (THIRD OUTER GLUME) and HvPLA1 (Plastochron1) genes.

Conclusions

Our data suggest that some of the roles of miR171 and its target genes that have been determined in Arabidopsis are conserved in barley and that they have additional functions in barley including activation of the miR156 pathway.

Keywords:
Barley; miR171; Scarecrow-like; Phase change; Meristems; Flowering time