Nodule-specific AhPUGN1.1 positively regulates nodulation in peanuts

Abstract

Peanut (Arachis hypogaea) is a widely cultivated legume crop that can fix nitrogen by forming root nodules with compatible rhizobia. The initiation and formation of these nodules require complex molecular communication between legumes and rhizobia, involving the precise regulation of multiple legume genes. However, the mechanism underlying nodulation in peanuts remains poorly understood. In this study, we identified a gene associated with nodulation in peanuts, named Peanut unique gene for nodulation 1.1 (AhPUGN1.1). Multiple lines of evidence indicate that AhPUGN1.1 is primarily expressed in peanut nodules. Silencing or knocking out AhPUGN1.1 in peanut resulted in fewer nodules, as well as lower fresh weight and nitrogenase activity, while overexpressing AhPUGN1.1 significantly enhanced nodulation ability and nitrogenase activity. Modulating the expression of AhPUGN1.1 also influenced the expression levels of genes associated with the Nod factor signaling pathway and infection via crack entry. Comparative transcriptome analysis revealed that AhPUGN1.1 likely regulates peanut nodulation by affecting the expression of genes involved in the cytokinin and calcium signaling pathways. Our data thus show that AhPUGN1.1 acts as a crucial regulator promoting symbiotic nodulation in peanuts.