Nodulation (nod) factors are signal molecules produced by bacteria known as rhizobia during the initiation of nodules on the root of legumes. Rhizobia (from the Greek words Riza = Root and Bios = Life) are soil bacteria that fix nitrogen (diazotrophy) after becoming established inside root nodules of legumes (Fabaceae). ... Root nodules occur on the roots of plants that associate with symbiotic bacteria. ... Varieties of soybean seeds, a popular legume A flowering legume The term legume has two closely related meanings in botany, a situation encountered with many botanical common names of useful plants whereby an applied name can refer to either the plant itself, or to the edible fruit (or useful part). ...

Nod factors structurally are lipochitooligosaccharides that consist of an acylated chitin oligomeric backbone with various functional group substitutions at the terminal or non-terminal residues. The exact chemical structure of the nod factor that is recognised by the plant varies between species and is the basis for host-symbiont specificity. Structure of chitin molecule In biology, chitin (pronounced keye-tin) is one of the main components in the cell walls of fungi, the exoskeletons of insects and other arthropods, and in some other animals. ...