| Neighbor interactions in dioecious plants are essential for population stability.Root exudates are considered key mediators for underground chemical communications and interactions among plant species.Arbuscular mycorrhizal fungi(AMF)have been found to affect the neighbor interactions by changing plant root exudates,but whether they can mediate sexual-related interactions by this way remains an open question.To explore whether changes in plant root exudates induced by AMF colonization affect intraspecific interaction in dioecious plants,we collected root exudates of Morus alba seedlings from different cultivation patterns(F,female mono-cultivation pattern;M,male monocultivation pattern;FF,female-female co-cultivation pattern;FM,female-male cocultivation pattern;MM,male-male co-cultivation pattern)before and after inoculating with Funneliformis mosseae respectively.The root exudate compositions were detected by GC-TOF-MS and the root exudated metabolites were putatively annotated based on LECO-Fiehn Rtx5 Library.Then,according to similarity > 500,68 annotated metabolites were selected for statistical analysis of the differences between different cultivation patterns and between before and after AMF inoculation.The main results were summarized as follows:1.Annotated metabolites in root exudate of M.alba are distributed in eight superclasses: lipids and lipid-like molecules,organic acids and derivatives,organic oxygen compounds,organoheterocyclic compounds,benzenoids,organic nitrogen compounds,homogeneous non-metal compounds and hydrocarbons.Among them,lipids and lipid molecules were the superclasses with the most species(35.3%)and relative content(42.233%)in the annotated root exudates of mulberry seedlings.In addition,β-Mannoseglycerate,D-xylose,and N-ethylmaleamic acid were found only in root exudates of cultivation patterns in the presence of female plants,indicated that they may only be secreted by females,while males do not.2.Inoculation AMF significantly increased the difference in root exudates between female and male M.alba in mono-cultivation pattern,and significant differences in the abundance of common components between female and male only be found after inoculation.There were obvious sex differences in root exudates of female and male mulberry after AMF inoculating,because the number of differential metabolites in female root exudates was much higher than that in male plants and the composition of differential components also vary a lot between the two.3.Inoculation AMF significantly enhanced the response of female and male M.alba to their neighbors with the same or opposite sex.Only after AMF inoculating,there were significant differences in composition and abundance of root exudates between female mono-cultivation and female-female co-cultivation pattern,between male monocultivation and male-male co-cultivation pattern,and between female mono-cultivation and female-male co-cultivation pattern.There were sex differences in the response of female and male plants to the same or opposite sex neighbors in terms of root exudates.When cultivated with the same sex neighbor,the abundance of most differential metabolites in the root exudates of female plants decreased,while the abundance of most differential compounds in the root exudates of male plants increased significantly.When cultivated with the opposite sex neighbor,the abundance of most differential metabolites in root exudates of female-male co-cultivation pattern was significantly lower than that of female mono-cultivation pattern,but there was no significant difference from that of male mono-cultivation pattern.4.Inoculation AMF also increased the difference in root exudates of M.alba between different sex combination cultivation patterns.The abundance of significant differences in root exudates between male-male co-cultivation and female-female co-cultivation pattern,and between male-male co-cultivation and female-male co-cultivation pattern differed significantly only after AMF inoculation.Moreover,the abundance of most differential metabolites in root exudates of male-male co-cultivation pattern was significantly higher than that of both female-female co-cultivation and female-male cocultivation pattern,while there was no significant difference in root exudates between female-female co-cultivation and female-male co-cultivation patter.The above results showed that AMF colonization caused the different profiles of root exudate between female and male mulberry,enhanced the sex-specific response to neighbor,and thus resulted in the different root exudate profiles among co-cultivation patterns.This may indicate that AMF has an effect on the neighbor interaction of dioecious plants by inducing different profiles in root exudates of host plants.Our results reveal a potential way for AMF to regulate the neighbor interaction of dioecious plants,and also can be used as a theoretical basis for improving the strategy of mulberry cultivation management in agriculture and forestry. |
