Nitrogen Fixation

Legume-Rhizobium Symbiosis and Root Nodule Formation

Root
Nodule
Rhizobia
N₂
NH₄⁺
N₂ Fixed
0
Generation:0
Free Rhizobia:0
Nodules:0
Bacteroids:0
Plant N:0

Nitrogen Fixation

Rhizobia bacteria infect legume roots and form nodules. Inside, they differentiate into bacteroids that fix atmospheric N₂ into NH₄⁺. The plant provides carbon in exchange. This symbiosis is suppressed when soil nitrogen is high (why fix when N is available?).