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Overexpression of miR160 affects root growth and nitrogen-fixing nodule number in Medicago truncatula

journal contribution
posted on 2024-08-21, 04:08 authored by Pilar Bustos-Sanmamed, Guohong Mao, Ying Deng, Morgane Elouet, Ghazanfar Abbas Khan, Jeremie Bazin, Marie Turner, Senthil Subramanian, Oliver Yu, Martin Crespi, Christine Lelandais-Briere
Auxin action is mediated by a complex signalling pathway involving transcription factors of the auxin response factor (ARF) family. In Arabidopsis, microRNA160 (miR160) negatively regulates three ARF genes (ARF10/ARF16/ARF17) and therefore controls several developmental processes, including primary and lateral root growth. Here, we analysed the role of miR160 in root development and nodulation in Medicago truncatula Gaertn. Bioinformatic analyses identified two main mtr-miR160 variants (mtr-miR160abde and mtr-miR160c) and 17 predicted ARF targets. The miR160-dependent cleavage of four predicted targets in roots was confirmed by analysis of parallel analysis of RNA ends (PARE) data and RACE-PCR experiments. Promoter-GUS analyses for mtr-miR160d and mtr-miR160c genes revealed overlapping but distinct expression profiles during root and nodule development. In addition, the early miR160 activation in roots during symbiotic interaction was not observed in mutants of the nodulation signalling or autoregulation pathways. Composite plants that overexpressed mtr-miR160a under two different promoters exhibited distinct defects in root growth and nodulation: the p35S:miR160a construct led to reduced root length associated to a severe disorganisation of the RAM, whereas pCsVMV:miR160a roots showed gravitropism defects and lower nodule numbers. Our results suggest that a regulatory loop involving miR160/ARFs governs root and nodule organogenesis in M. truncatula.

History

Journal

FUNCTIONAL PLANT BIOLOGY

Volume

40

Pagination

1208-1220

Location

Australia

ISSN

1445-4408

eISSN

1445-4416

Language

English

Publication classification

C1.1 Refereed article in a scholarly journal

Issue

12

Publisher

CSIRO PUBLISHING