Question

During symbiotic biological nitrogen fixation. The recognition of Rhizobia host interaction involves two classes of molecules there are _______________.

• A. Lectins an lipids
• B. Lectins and Polysaccharides
• C. Flavonoids and Oligosaccharides
• D. Lectins and Alkaloids

Answer 1

Answer: (C)

Flavonoids and Oligosaccharides

Rhizobium–legume symbioses are of great ecological and agronomic importance, due to their ability to fix large amounts of atmospheric nitrogen. These symbioses result in the formation on legume roots of differentiated organs called nodules, in which the bacteria reduce nitrogen into ammonia used by the host plant.

Nodulation begins with the exchange of chemical signals. Plants secrete flavonoids into the rhizosphere that activate rhizobial nod genes via the transcriptional activator NodD. nod gene expression leads to the synthesis of the bacterial chemical signal, Nod factor, a lipochitin oligosaccharide.

Rhizobium infections are species-specific. Compatibility is determined by both the species-specific Nod factors and the flavonoid–NodD interaction.

So the correct answer is option C.