Journal Article

LACK OF SYMBIONT ACCOMMODATION controls intracellular symbiont accommodation in root nodule and arbuscular mycorrhizal symbiosis in Lotus japonicus

Suzaki, Takuya, Miura, Kenji, Misawa, Fumika, Ito, Momoyo, Hoshino, Motomi, Nishida, Hanna, Kawaguchi, Masayoshi, Takeda, Naoya, Handa, Yoshihiro

2019

Overview

Nitrogen-fixing rhizobia and arbuscular mycorrhizal fungi (AMF) form symbioses with plant roots and these are established by precise regulation of symbiont accommodation within host plant cells. In model legumes such as Lotus japonicus and Medicago truncatula, rhizobia enter into roots through an intracellular invasion system that depends on the formation of a root-hair infection thread (IT). While IT-mediated intracellular rhizobia invasion is thought to be the most evolutionarily derived invasion system, some studies have indicated that a basal intercellular invasion system can replace it when some nodulation-related factors are genetically modified. In addition, intracellular rhizobia accommodation is suggested to have a similar mechanism as AMF accommodation. Nevertheless, our understanding of the underlying genetic mechanisms is incomplete. Here we identify a L. japonicus nodulation-deficient mutant, with a mutation in the LACK OF SYMBIONT ACCOMMODATION (LAN) gene, in which root-hair IT formation is strongly reduced, but intercellular rhizobial invasion eventually results in functional nodule formation. LjLAN encodes a protein that is homologous to Arabidopsis MEDIATOR 2/29/32 possibly acting as a subunit of a Mediator complex, a multiprotein complex required for gene transcription. We also show that LjLAN acts in parallel with a signaling pathway including LjCYCLOPS. In addition, the lan mutation drastically reduces the colonization levels of AMF. Taken together, our data provide a new factor that has a common role in symbiont accommodation process during root nodule and AM symbiosis.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Arabidopsis / Arbuscular mycorrhizas / Bioinformatics / Biology and Life Sciences / Colonization / CRISPR / Deficient mutant / Engineering and Technology / Environmental science / Fungi / Gene Expression Regulation, Plant - genetics / Genes / Genetically modified organisms / Genomes / Hair / Host plants / Infection / Infections / Intracellular / Kinases / Legumes / Lotus (Legumes) / Lotus - genetics / Lotus - growth & development / Lotus - microbiology / Lotus japonicus / Medicago truncatula - genetics / Medicago truncatula - growth & development / Medicago truncatula - microbiology / Mutation / Mycorrhizae / Mycorrhizae - genetics / Mycorrhizae - growth & development / Nitrogen fixation / Nodulation / Observations / Parameter estimation / Physiological aspects / Plant cells / Plant Proteins - genetics / Plant Root Nodulation - genetics / Plant Roots - genetics / Plant Roots - growth & development / Plant Roots - microbiology / Proteins / Research and Analysis Methods / Rhizobium - genetics / Rhizobium - growth & development / Root Nodules, Plant - genetics / Root Nodules, Plant - growth & development / Root Nodules, Plant - microbiology / Roots / Signal transduction / Symbiosis / Symbiosis - genetics / Transcription / Transcription (Genetics)