1. Positive Gene Regulation by a Natural Protective miRNA Enables Arbuscular Mycorrhizal Symbiosis
- Author
-
Jean-Malo Couzigou, Bruno Guillotin, Caroline Gutjahr, Olivier André, Dominique Lauressergues, Guillaume Bécard, and Jean-Philippe Combier
- Subjects
0106 biological sciences ,0301 basic medicine ,Fungus ,Cleavage (embryo) ,Plant Roots ,01 natural sciences ,Microbiology ,03 medical and health sciences ,Downregulation and upregulation ,Symbiosis ,Gene Expression Regulation, Plant ,Mycorrhizae ,Virology ,Medicago truncatula ,Tobacco ,Botany ,microRNA ,Glomeromycota ,Regulation of gene expression ,Base Sequence ,biology ,fungi ,Meristem ,biology.organism_classification ,Cell biology ,Arbuscular mycorrhiza ,MicroRNAs ,030104 developmental biology ,Parasitology ,010606 plant biology & botany - Abstract
Arbuscular mycorrhizal (AM) symbiosis associates most plants with fungi of the phylum Glomeromycota. The fungus penetrates into roots and forms within cortical cell branched structures called arbuscules for nutrient exchange. We discovered that miR171b has a mismatched cleavage site and is unable to downregulate the miR171 family target gene, LOM1 (LOST MERISTEMS 1). This mismatched cleavage site is conserved among plants that establish AM symbiosis, but not in non-mycotrophic plants. Unlike other members of the miR171 family, miR171b stimulates AM symbiosis and is expressed specifically in root cells that contain arbuscules. MiR171b protects LOM1 from negative regulation by other miR171 family members. These findings uncover a unique mechanism of positive post-transcriptional regulation of gene expression by miRNAs and demonstrate its relevance for the establishment of AM symbiosis.
- Published
- 2017
- Full Text
- View/download PDF