title: Intracellular catalytic domain of symbiosis receptor kinase hyperactivates spontaneous nodulation in absence of rhizobia.
abstract: Symbiosis Receptor Kinase (SYMRK), a member of the Nod factor signaling pathway, is indispensible for both nodule organogenesis and intracellular colonization of symbionts in rhizobia-legume symbiosis. Here, we show that the intracellular kinase domain of a SYMRK (SYMRK-kd) but not its inactive or full-length version leads to hyperactivation of the nodule organogenic program in Medicago truncatula TR25 (symrk knockout mutant) in the absence of rhizobia. Spontaneous nodulation in TR25/SYMRK-kd was 6-fold higher than rhizobia-induced nodulation in TR25/SYMRK roots. The merged clusters of spontaneous nodules indicated that TR25 roots in the presence of SYMRK-kd have overcome the control over both nodule numbers and their spatial position. In the presence of rhizobia, SYMRK-kd could rescue the epidermal infection processes in TR25, but colonization of symbionts in the nodule interior was significantly compromised. In summary, ligand-independent deregulated activation of SYMRK hyperactivates nodule organogenesis in the absence of rhizobia, but its ectodomain is required for proper symbiont colonization.
authors.affiliation: Department of Biochemistry, University of Calcutta, Calcutta 700019, India.
authors.forename: Sudip
authors.initials: S
authors.lastname: Saha
authors.affiliation: Department of Biochemistry, University of Calcutta, Calcutta 700019, India.
authors.forename: Ayan
authors.initials: A
authors.lastname: Dutta
authors.affiliation: Department of Biochemistry, University of Calcutta, Calcutta 700019, India.
authors.forename: Avisek
authors.initials: A
authors.lastname: Bhattacharya
authors.affiliation: Department of Biochemistry, University of Calcutta, Calcutta 700019, India maitrayee_d@hotmail.com.
authors.forename: Maitrayee
authors.initials: M
authors.lastname: DasGupta
mesh_terms: D010367:Arachis / Q000201:enzymology / Q000235:genetics; D020134:Catalytic Domain; D003593:Cytoplasm / Q000378:metabolism; D015870:Gene Expression; D017930:Genes, Reporter; D046913:Medicago truncatula / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000378:metabolism; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D053204:Root Nodules, Plant / Q000201:enzymology / Q000235:genetics / Q000382:microbiology; D015398:Signal Transduction; D016962:Sinorhizobium meliloti / Q000502:physiology*; D013559:Symbiosis
chemical_list: D010940:Plant Proteins; D011494:Protein Kinases