Dynamics of miRNA mediated regulation of legume symbiosis

Plant Cell Environ. 2021 May;44(5):1279-1291. doi: 10.1111/pce.13983. Epub 2021 Jan 13.


Symbiotic nitrogen fixation in legume nodules is important in soils with low nitrogen availability. The initiation and sustainability of symbiosis require cellular reprogramming that involves the miRNA-mediated inhibition or activation of specific nodulation genes. The high-throughput sequencing of small RNA libraries has identified miRNAs and their targets, which are the major players in the post-transcriptional gene regulation (PTGS) of the different stages of legume-rhizobia symbiosis ranging from bacterial colonization and organogenesis to symbiotic nitrogen fixation. Here, we present an overview of information obtained from the miRNA libraries from nodulating tissues that have been sequenced to date. The functional analysis of miRNAs has revealed roles in phytohormone homeostasis and spatio-temporal regulation, as well as the mobility of miRNAs and their functions in shoot to root signalling that affects diverse functions, including bacterial entry, meristem division and differentiation, nitrogen fixation and senescence. Furthermore, small RNA fragments of rhizobial origin repress complementary plant mRNAs. We also consider the roles of miRNAs in determinate or indeterminate nodules. Taken together, this overview confirms that miRNAs are master regulators of the legume-rhizobia symbiosis.

Keywords: NGS; auxin; cytokinin; microarray; rhizobia.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Fabaceae / genetics*
  • Gene Expression Regulation, Plant*
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Plant Growth Regulators / metabolism
  • Plant Root Nodulation / genetics
  • Symbiosis / genetics*


  • MicroRNAs
  • Plant Growth Regulators