A Nitrogen Fixing Symbiosis-specific Pathway Requiredfor Legume Flowering
Published:30 Jan.2023    Source:Plant Scineces
Symbioticnitrogen fixation boosts legumegrowth and productionin nitrogen-poorsoils. It has long beenassumedthat fixed nitrogen increases reproductive success,but until now, the regulatory mechanismwasunknown. Here, we report a symbioticflowering pathway that couplessymbioticand nutrientsignals to theflowering inductionpathway in legumes.We show that the symbioticmicro RNA–microRNA172c (miR172c)and fixed nitrogen systemicallyand synergistically convey symbioticand nutritionalcues from rootsto leavestopromotesoybean (Glycinemax) flowering. The combinations of symbiotic miR172 candlocal miR172 celicitedby fixed nitrogen and developmentin leaves activate florigen-encoding FLOWERING LOCUST (FT) homologs (GmFT2a/5a) by repressing TARGET OF EAT1-like 4a (GmTOE4a). Thus, FTs trigger reproductive development,which allows legumesto survive and reproduce under low-nitrogen conditions.