Soybean ureases, but not that of Bradyrhizobium japonicum, are involved in the process of soybean root nodulation.
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.
Graduate Program in Cellular and Molecular Biology, Center of Biotechnology and #Department of Biophysics and Center of Biotechnology, Universidade Federal do Rio Grande do Sul , Porto Alegre, Rio Grande do Sul CEP 91501-970, Brazil.
Mônica
M
Medeiros-Silva
William L
WL
Franck
Marcela P
MP
Borba
Sabrina B
SB
Pizzato
Kent N
KN
Strodtman
David W
DW
Emerich
Gary
G
Stacey
Joseph C
JC
Polacco
Célia R
CR
Carlini
D020369:Bradyrhizobium / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism*; D055170:Plant Root Nodulation; D053204:Root Nodules, Plant / Q000201:enzymology* / Q000382:microbiology; D013025:Glycine max / Q000201:enzymology* / Q000382:microbiology / Q000502:physiology; D013559:Symbiosis; D014510:Urease / Q000378:metabolism*
D010940:Plant Proteins; D014510:Urease