MiR171h restricts root symbioses and shows like its target NSP2 a complex transcriptional regulation in Medicago truncatula

BMC Plant Biology

Research Article

Vinzenz Hofferek¹  Nicole Gaude¹  Franziska Krajinski¹  Amelie Mendrinna¹  Emanuel A Devers² 

[1] Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam, 14476, Golm, OT, Germany;Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam, 14476, Golm, OT, Germany;Present address: Department of Biology, Swiss Federal Institute of Technology Zurich, Zürich, Switzerland;

关键词: Symbiosis;    Plant miRNA;    miR171h;    NSP2;    Plant nutrition;   

DOI  :  10.1186/s12870-014-0199-1

 received in 2014-02-18, accepted in 2014-07-15,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundLegumes have the unique capability to undergo root nodule and arbuscular mycorrhizal symbiosis. Both types of root endosymbiosis are regulated by NSP2, which is a target of microRNA171h (miR171h). Although, recent data implies that miR171h specifically restricts arbuscular mycorrhizal symbiosis in the root elongation zone of Medicago truncatula roots, there is limited knowledge available about the spatio-temporal regulation of miR171h expression at different physiological and symbiotic conditions.ResultsWe show that miR171h is functionally expressed from an unusual long primary transcript, previously predicted to encode two identical miR171h strands. Both miR171h and NSP2 transcripts display a complex regulation pattern, which involves the symbiotic status and the fertilization regime of the plant. Quantitative Real-time PCR revealed that miR171h and NSP2 transcript levels show a clear anti-correlation in all tested conditions except in mycorrhizal roots, where NSP2 transcript levels were induced despite of an increased miR171h expression. This was also supported by a clear correlation of transcript levels of NSP2 and MtPt4, a phosphate transporter specifically expressed in a functional AM symbiosis. MiR171h is strongly induced in plants growing in sufficient phosphate conditions, which we demonstrate to be independent of the CRE1 signaling pathway and which is also not required for transcriptional induction of NSP2 in mycorrhizal roots. In situ hybridization and promoter activity analysis of both genes confirmed the complex regulation involving the symbiotic status, P and N nutrition, where both genes show a mainly mutual exclusive expression pattern. Overexpression of miR171h in M. truncatula roots led to a reduction in mycorrhizal colonization and to a reduced nodulation by Sinorhizobium meliloti.ConclusionThe spatio-temporal expression of miR171h and NSP2 is tightly linked to the nutritional status of the plant and, together with the results from the overexpression analysis, points to an important function of miR171h to integrate the nutrient homeostasis in order to safeguard the expression domain of NSP2 during both, arbuscular mycorrhizal and root nodule symbiosis.

【 授权许可】

Unknown   
© Hofferek et al. 2014. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.