Effects of GmERF5-Responsive Effector on Soybean Symbiotic Nodulation

Abstract

The type III secretion system (T3SS) of Rhizobium plays a crucial role during the establishment of the soybean (Glycine max (L.) Merr.)-Rhizobium symbiosis system. Additionally, host-specific nodulation may also depend on the Nops (nodulation outer proteins) secreted by the T3SS of Rhizobium. However, there is limited understanding of the response of soybean genes to Nops. In this study, a NopC mutant, HH103ΩNopC, was constructed from Sinorhizobium fredii HH103 and then utilized to assess the impact of the NopC on nodulation. An RNA-seq analysis revealed that the GmERF5 (Glycine max Ethylene Responsive Factor 5) gene was induced by NopC, which was confirmed by qRT-PCR. Furthermore, an overexpression of the GmERF5 hair-root system was constructed to investigate the effect of GmERF5 on nodulation and its interaction with NopC. Differences in nodule number and nodule dry weight in the overexpression of the GmERF5 hair-root system supported the conclusion that GmERF5 can regulate soybean nodule phenotype via NopC. These results elucidate the genetic mechanisms that regulate nodule phenotype in soybean.