华中农业大学生物固氮团队解析了大豆根瘤衰老的分子调控机制

　　Root nodules are major sources of nitrogen for soybean （Glycine max （L.� Merr.� growth, development, production, and seed quality. Symbiotic nitrogen fixation is time-limited, as the root nodule senesces during the reproductive stage of plant development, specifically during seed development. Nodule senescence is characterized by the induction of senescence-related genes, such as papain-like cysteine proteases （CYPs）， which ultimately leads to the degradation of both bacteroids and plant cells. However, how nodule senescence�Crelated genes are activated in soybean is unknown. Here, we identified two paralogous NAC trans cription factors, GmNAC039 and GmNAC018, as master regulators of nodule senescence. Overex pression of either gene induced soybean nodule senescence with increased cell death as detected using a TUNEL assay, wher eas their knockout delayed senescence and increased nitrogenase activity. Trans criptome analysis and nCUT&Tag-qPCR assays revealed that GmNAC039 directly binds to the core motif CAC（A）A and activates the ex pression of four GmCYP genes （GmCYP35, GmCYP37, GmCYP39 and GmCYP45）� Similar to GmNAC039 and GmNAC018, overex pression or knockout of GmCYP genes in nodules resulted in precocious or delayed senescence, respectively. These data provide essential insights into the regulatory mechanisms of nodule senescence, in which GmNAC039 and GmNAC018 directly activate the ex pression of GmCYP genes to promote nodule senescence.

　　论文链接：https://doi.org/10.1093/plcell/koad129