Soybean Ureases, but Not That of Bradyrhizobium japonicum, Are Involved in the Process of Soybean Root Nodulation

Abstract

Ureases are abundant in plants, bacteria, and in the soil, but their role in signaling between soybean and soil microorganisms has not been investigated. The bacterium Bradyrhizobium japonicum forms nitrogen-fixing nodules on soybean roots. Here, we evaluated the role(s) of ureases in the process of soybean nodulation. Chemotaxis assays demonstrated that soybean and jack bean ureases were more chemotactic toward bacterial cells than the corresponding plant lectins. The eu1-a,eu4 soybean, deficient in urease isoforms, formed fewer but larger nodules than the wild-type, regardless of the bacterial urease phenotype. Leghemoglobin production in wild-type plants was higher and peaked earlier than in urease-deficient plants. Inhibition of urease activity in wild-type plants did not result in the alterations seen in mutated plants. We conclude that soybean urease(s) play(s) a role in the soybean-B. japonicum symbiosis, which is independent of its ureolytic activity. Bacterial urease does not play a role in nodulation.

Gel-free proteomic analysis of soybean root proteins affected by calcium under flooding stress

“…The suppression of embryo-specific urease in soybean led to increased susceptibility to fungal infection, demonstrating that urease plays a role in plant defense (Wiebke-strohm et al, 2012 ). Medeiros-Silva et al ( 2014 ) reported that a urease deficiency in soybean altered the physiology of root nodules and adversely affected nitrogen fixation. Consistent with our present findings, Jack bean urease activity was affected by intra- and extracellular calcium concentrations (Staniscuaski et al, 2009 ).…”

Ureases: Historical aspects, catalytic, and non-catalytic properties – A review

“…Ureases were evaluated for a role in soybean nodulation by the diazotrophic bacterium Bradyrhizobium japonicum [140] . Soybean and jack bean ureases were characterized as chemotactic factors recognized by the bacterial cells in vitro .…”

Fungal endophyte Phomopsis liquidambari biodegrades soil resveratrol: a potential allelochemical in peanut monocropping systems

“…Leghemoglobin contents in peanut nodules were detected by measuring the absorbance of heme under the oxidation state and the reduction state (pyridine‐heme assay) as previously described …”

“…Leghemoglobin contents in peanut nodules were detected by measuring the absorbance of heme under the oxidation state and the reduction state (pyridine-heme assay) as previously described. 26 Soil dehydrogenase activity Soil microbial biomass was detected based on the 2,3,5-triphenyltetrazolium chloride (TTC) reduction method as described by Casida et al 27 Briefly, 5 g of fresh rhizosphere soil was incubated with TTC solution at 37 ∘ C for 24 h in the dark. Dehydrogenase activity was defined as the concentration of generated triphenylformazan (TRF) measured at 485 nm.…”