Role of in Regulating Soybean Nodule Formation Under Cold Stress.

Symbiotic nitrogen fixation, recognized as the most efficient nitrogen assimilation system in ecosystems, is essential for soybean growth, as nodulation provides critical nitrogen to host cells. Soybeans thrive in warm and moist environments. However, they are highly susceptible to low temperatures, which impede the formation and development of root nodules. The genetic basis and molecular mechanism underlying the inhibition of nodulation induced by low temperatures remain unclear. In this study, we conducted a comparative transcriptomic analysis of soybean roots inoculated with rhizobium at 1 DPI (Day Post Inoculation) under normal or cold treatments. We identified 39 up-regulated and 35 down-regulated genes associated with nodulation and nitrogen fixation. Notably, cold-responsive genes including three () family genes were identified among differentially expressed genes (DEGs). Further expression pattern analysis of demonstrated it being significantly responsive to rhizobium inoculation and its highest expression in nodules. Further investigation revealed that overexpression of led to an increase in the nodule number, while RNA interference (RNAi)-mediated gene editing of suppressed nodule formation. Additionally, overexpression may regulate soybean nodulation by modulating the expression of (NODULE INCEPTION), (nodulation signaling pathway 1), and (histone- or haem-associated protein domain) in the nod factor signaling pathway. This study offers new insights into the genetic basis of nodulation regulation under cold stress in legumes and indicates that may serve as a key regulator of nodule formation under cold stress.