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MicroRNA166 controls root and nodule development in Medicago truncatula

MicroRNA166 controls root and nodule development in Medicago truncatula Legume root architecture is characterized by the development of two de novo meristems, leading to the formation of lateral roots or symbiotic nitrogen‐fixing nodules. Organogenesis involves networks of transcription factors, the encoding mRNAs of which are frequently targets of microRNA (miRNA) regulation. Most plant miRNAs, in contrast with animal miRNAs, are encoded as single entities in an miRNA precursor. In the model legume Medicago truncatula, we have identified the MtMIR166a precursor containing tandem copies of MIR166 in a single transcriptional unit. These miRNAs post‐transcriptionally regulate a new family of transcription factors associated with nodule development, the class‐III homeodomain‐leucine zipper (HD‐ZIP III) genes. In situ expression analysis revealed that these target genes are spatially co‐expressed with MIR166 in vascular bundles, and in apical regions of roots and nodules. Overexpression of the tandem miRNA precursor correlated with MIR166 accumulation and the downregulation of several class‐III HD‐ZIP genes, indicating its functionality. MIR166 overexpression reduced the number of symbiotic nodules and lateral roots, and induced ectopic development of vascular bundles in these transgenic roots. Hence, plant polycistronic miRNA precursors, although rare, can be processed, and MIR166‐mediated post‐transcriptional regulation is a new regulatory pathway involved in the regulation of legume root architecture. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Plant Journal Wiley

MicroRNA166 controls root and nodule development in Medicago truncatula

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References (59)

Publisher
Wiley
Copyright
Copyright © 2008 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0960-7412
eISSN
1365-313X
DOI
10.1111/j.1365-313X.2008.03448.x
pmid
18298674
Publisher site
See Article on Publisher Site

Abstract

Legume root architecture is characterized by the development of two de novo meristems, leading to the formation of lateral roots or symbiotic nitrogen‐fixing nodules. Organogenesis involves networks of transcription factors, the encoding mRNAs of which are frequently targets of microRNA (miRNA) regulation. Most plant miRNAs, in contrast with animal miRNAs, are encoded as single entities in an miRNA precursor. In the model legume Medicago truncatula, we have identified the MtMIR166a precursor containing tandem copies of MIR166 in a single transcriptional unit. These miRNAs post‐transcriptionally regulate a new family of transcription factors associated with nodule development, the class‐III homeodomain‐leucine zipper (HD‐ZIP III) genes. In situ expression analysis revealed that these target genes are spatially co‐expressed with MIR166 in vascular bundles, and in apical regions of roots and nodules. Overexpression of the tandem miRNA precursor correlated with MIR166 accumulation and the downregulation of several class‐III HD‐ZIP genes, indicating its functionality. MIR166 overexpression reduced the number of symbiotic nodules and lateral roots, and induced ectopic development of vascular bundles in these transgenic roots. Hence, plant polycistronic miRNA precursors, although rare, can be processed, and MIR166‐mediated post‐transcriptional regulation is a new regulatory pathway involved in the regulation of legume root architecture.

Journal

The Plant Journal – Wiley

Published: Jun 1, 2008

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