Research progress on molecular mechanisms of autoregulation of nodulation in legumes

Legumes form symbionts with rhizobia leading to the development of nitrogen fixing root nodules, while rhizobium in nodules convert nitrogen gas to ammonia for plant development.To balance nitrogen uptake and energy loss during symbiosis, legumes regulate nodule number through an autoregulation of nodulation (AON) systemic pathways.This paper reviewed the recent research progress on the molecular regulatory mechanism of AON and detailed the functions of key genes in host plants that regulate AON and the effects of environmental factors on the AON system, including the roles of underground peptide signals, aboveground receptor kinase, long distance signaling (Cytokinins, auxin and miR2111) and F-box protein in root.Some questions remained to be answered in the AON were discussed to provide information and reference for studies related to AON.