AUTHOR=Chen Xue , Li Qiao , Wang Liting , Meng Yanliang , Jiao Shaona , Yin Jilin , Xu Haiyun , Zhang Fengjuan 

TITLE=Nitrogen Uptake, Not Transfer of Carbon and Nitrogen by CMN, Explains the Effect of AMF on the Competitive Interactions Between Flaveria bidentis and Native Species

JOURNAL=Frontiers in Ecology and Evolution

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2021.625519

DOI=10.3389/fevo.2021.625519

ISSN=2296-701X

ABSTRACT=<p><italic>Rhizophagus intraradices</italic>, one of the common arbuscular mycorrhizal fungi (AMF) grown in the roots of <italic>Flaveria bidentis</italic>, facilitates the invasion of this exotic plant species into China. However, it is still unknown whether nutrient transfer through the common mycorrhizal networks (CMN) between this exotic species and the native species enhances the competitive growth of <italic>F. bidentis</italic> over the native species. To elucidate this question and the related mechanism, an isotopic labeling technique was used to test the transfer of carbon (C) and nitrogen (N) by CMN. Native species like <italic>Setaria viridis</italic> and <italic>Eclipta prostrata</italic> were selected to compete with <italic>F. bidentis</italic> in a polyvinyl chloride (PVC) box. Two competitive groups (<italic>F. bidentis</italic>-<italic>S. viridis</italic> and <italic>F. bidentis</italic>- <italic>E. prostrata</italic>), three treatments (monoculture of <italic>F. bidentis</italic>, the mixture of <italic>F. bidentis</italic> and the native plant, and the monoculture of the native plant), and two levels of AMF (presence or absence) were assigned. Results showed that the corrected index of relative competition intensity (CRCI) of <italic>F. bidentis</italic> in the presence of AMF &lt; 0 suggests that the competition facilitated the growth of <italic>F. bidentis</italic> with either <italic>S. viridis</italic> or <italic>E. prostrata</italic>. The reason was that the inoculation of <italic>R. intra radices</italic> significantly increased the C and N contents of <italic>F. bidentis</italic> in the mixtures. However, the effects of <italic>R. intra radices</italic> on the two native species were different: negative effect on the growth of <italic>S. viridis</italic> and positive effect on the growth of <italic>E. prostrata</italic>. The change of N content in <italic>S. viridis</italic> or <italic>E. prostrata</italic> was consistent with the variation of the biomass, suggesting that the N uptake explains the effects of <italic>R. intraradices</italic> on the competitive interactions between <italic>F. bidentis</italic> and the two native species. Moreover, the transfer of C and N <italic>via</italic> AMF hyphal links did occur between <italic>F. bidentis</italic> and the native species. However, the transfer of C and N by the CMN was not positively related to the competitive growth of <italic>F. bidentis</italic>.</p>