The nodule transcriptome of Onobrychis viciifolia

The legume nodule is a specialized organ where endosymbiotic bacteria convert atmospheric nitrogen into ammonia. Nodule-expressed genes called nodulins, are indispensable players for nodule functioning. Depending on the legume species, the developmental program of the nodule can be determinate or indeterminate, and the legume host can impose reversible or irreversible differentiation to its rhizobial partner. Therefore, it is feasible that such differences have impacted the composition and expression profile of certain gene families of nodulins. To investigate this hypothesis, the nodule transcriptome was sequenced from Onobrychis viciifolia and others five legumes of the inverted-repeat lacking clade (IRLC), where nodules are indeterminate and the bacteroids terminally differentiated.