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The deubiquitinating enzyme AMSH 1 is required for rhizobial infection and nodule organogenesis in Lotus japonicus
Author(s) -
Małolepszy Anna,
Urbański Dorian Fabian,
James Euan K.,
Sandal Niels,
Isono Erika,
Stougaard Jens,
Andersen Stig Uggerhøj
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12922
Subject(s) - lotus japonicus , rhizobia , biology , deubiquitinating enzyme , organogenesis , mutant , lotus , microbiology and biotechnology , ubiquitin , symbiosis , cytokinin , root nodule , botany , biochemistry , gene , auxin , genetics , bacteria
Summary Legume–rhizobium symbiosis contributes large quantities of fixed nitrogen to both agricultural and natural ecosystems. This global impact and the selective interaction between rhizobia and legumes culminating in development of functional root nodules have prompted detailed studies of the underlying mechanisms. We performed a screen for aberrant nodulation phenotypes using the Lotus japonicus LORE 1 insertion mutant collection. Here, we describe the identification of amsh1 mutants that only develop small nodule primordia and display stunted shoot growth, and show that the aberrant nodulation phenotype caused by LORE 1 insertions in the Amsh1 gene may be separated from the shoot phenotype. In amsh1 mutants, rhizobia initially became entrapped in infection threads with thickened cells walls. Some rhizobia were released into plant cells much later than observed for the wild‐type; however, no typical symbiosome structures were formed. Furthermore, cytokinin treatment only very weakly induced nodule organogenesis in amsh1 mutants, suggesting that AMSH 1 function is required downstream of cytokinin signaling. Biochemical analysis showed that AMSH 1 is an active deubiquitinating enzyme, and that AMSH 1 specifically cleaves K63‐linked ubiquitin chains. Post‐translational ubiquitination and deubiquitination processes involving the AMSH 1 deubiquitinating enzyme are thus involved in both infection and organogenesis in Lotus japonicus .