JA Signaling Inhibitor JAZ Is Involved in Regulation of AM Symbiosis with Cassava, Including Symbiosis Establishment and Cassava Growth

Mutualism between plants and arbuscular mycorrhizal fungi (AMF) is imperative for sustainable agricultural production. Jasmonic acid (JA) signal transduction has been demonstrated to play an important role in AMF symbiosis with the host. In this study, SC9 cassava was selected as the research object to investigate the effect of the jasmonic acid signaling pathway on symbiosis establishment and cassava growth in AMF and cassava symbiosis. It was first found that the symbiosis of cassava and mycorrhizal fungi could increase the biomass of both the aboveground and belowground parts of cassava. Secondly, JA content increased significantly in the early stage of AMF inoculation and auxin content increased significantly in the late stage of AMF inoculation, suggesting that JA signal transduction played an important role in the symbiosis between cassava and mycorrhizal fungi. Transcriptome data were used to analyze the expression differences of genes related to JA synthesis and signal transduction in cassava. The <i>MeJAZ</i> gene positively responded to symbiosis between cassava and mycorrhizal fungi. The analysis of MeJAZ gene family expression and its promoter supported this result. Spraying different concentrations of MeJA on leaves could affect the colonization rate and root biomass of cassava, indicating that JA was an active regulator of mycorrhizal formation. PPI prediction and qPCR analysis suggested that the <i>MeJAZ7</i> gene might be a key transcriptional regulator responding to jasmonic acid signals and regulating mycorrhizal influence on cassava growth and development.