nodulation

In general, nonlegumes were assumed to lack the ability to respond to the rhizobial lipo-chitin Nod factors, which are the essential signal molecules that trigger legume nodulation.

This is consistent with nodulation pre-dating the WGD and further sub- and neo-functionalization emerging afterwards.

Our results indicate that the WGD early in papilionoid evolution allowed the emergence of critical components in Nod factor signalling and contributed to the complexity of rhizobial nodulation observed in this clade.

Phylogenetic studies suggest that nodulation may have evolved multiple times in the Fabidae, but the observation that all nodulating species are contained within this single clade indicates that a predisposition to nodulate evolved in their common ancestor.

It is unknown whether nodulation with rhizobia preceded the divergence of the three legume subfamilies or evolved on multiple occassions.