Abstract:In order to understand the function of common mycorrhizal networks (CMNs) among plants, its role in mechanical damage signal transduction of Medicago sativa was studied. The results showed that analyzed whether the damage signal of donor plants could be transmitted to the neighboring recipient plants through CMNs. The number and kinds of volatile compounds in leaves of recipient plants connected with CMNs were significantly higher than those connected without CMNs. The activities of defense enzyme also increased significantly in recipient plants connected with CMNs. Therefore, it was suggested that the defense signals induced by mechanical damage could be transmitted to neighboring plants through CMNs, which activates the defense system of neighboring plants, so that the nearby alfalfa plants without mechanical damage changed the volatile gas and the defense enzyme activity, so as to repair the damage caused by the damage.