Journal Article

Systemic control of legume susceptibility to rhizobial infection by a mobile microRNA

Markmann, Katharina, Reid, Dugald E., Madsen, Lene H., Sexauer, Moritz, Bhasin, Hemal, Abel, Nikolaj B., Tsikou, Daniela, Yan, Zhe, Holt, Dennis B., Stougaard, Jens

2018

Overview

Nitrogen fixation by legumes results from a symbiotic partnership between plant and microbes. These together elaborate nodules on the plant roots that house the bacteria. Tsikou et al. identified a microRNA made in the aboveground shoots of Lotus japonicus that translocates to the plant's roots. In the roots, the microRNA posttranscriptionally regulates a key suppressor of symbiosis, thus keeping the uninfected root susceptible to productive infection by symbiotic bacteria. Science , this issue p. 233 A microRNA made in the shoot regulates microbial nodulation in Lotus roots. Nitrogen-fixing root nodules on legumes result from two developmental processes, bacterial infection and nodule organogenesis. To balance symbiosis and plant growth, legume hosts restrict nodule numbers through an inducible autoregulatory process. Here, we present a mechanism where repression of a negative regulator ensures symbiotic susceptibility of uninfected roots of the host Lotus japonicus . We show that microRNA miR2111 undergoes shoot-to-root translocation to control rhizobial infection through posttranscriptional regulation of the symbiosis suppressor TOO MUCH LOVE in roots. miR2111 maintains a susceptible default status in uninfected hosts and functions as an activator of symbiosis downstream of LOTUS HISTIDINE KINASE1–mediated cytokinin perception in roots and HYPERNODULATION ABERRANT ROOT FORMATION1, a shoot factor in autoregulation. The miR2111- TML node ensures activation of feedback regulation to balance infection and nodulation events.

• Publisher: The American Association for the Advancement of Science
• Subject: Bacteria / Bacterial diseases / Control / Gene Expression Regulation, Bacterial / Histidine / Infections / Legumes / Lotus - microbiology / Lotus japonicus / MicroRNAs / MicroRNAs - genetics / miRNA / Nitrogen fixation / Nodulation / Nodules / Organogenesis / Plant Diseases - microbiology / Plant Diseases - prevention & control / Plant growth / Plant roots / Post-transcription / Rhizobium - genetics / Rhizobium - pathogenicity / Ribonucleic acid / RNA / Root nodules / Root Nodules, Plant - microbiology / Roots / Shoots / Symbiosis / Symbiosis - genetics / Translocation