Legume Rhizobium symbiosis Process
Establishment of Legume-Rhizobium symbiosis involves 2 way transfer of information to the legume root and from legume roots to the Rhizobium.
· Symbiosis begins with the colonization of the rhizosphere of young roots by rhizobium that can infect the particular host.
· The plants provides a sheathed “infection thread” which penetrates to the inner cortex and stimulate cortical cells to divide and produce the nodule structure.
· The developing nodule differentiates vascular tissues which flow of water, nutrients ions. The sugar to supply energy and nitrogen containing products likes amides.
· ·Since Nitrogenase enzyme required for N2 fixation is O2 sensitive, it is controlled by legume heamoglobin in the nodule tissue. The heamoglobin makes healthy legume nodule pink coloured. Generally, nodule form within 3 weeks after emergence of seedling.
In brief, the rhizobium inside the nodule fix significant amount of atmospheric N2 which is used by the legumes in return. The rhizobium gets shelter by receiving other nutrients from the legumes.
Therefore, this is a symbiotic association where both the partners mutually benefited.