The Black-spotted Pond Frog, Pelophylax nigromaculatus, is widely distributed across mainland China, Korean Peninsula, and Japan. The taxonomic relationships among P. n. nigromaculatus, Rana nigromaculata mongolia (sensu P. n. mongolicus), and P. tenggerensis have long been ambiguous. Here we examine the topotype specimens of P. tenggerensis and R. n. mongolia, and provide phylogenic analyses based on four mitochondrial DNA sequences. The combined evidences from morphology and molecular phylogeny have shown the distinct specific-level of P. n. mongolicus that distant from P. nigromaculatus, while indicating the homogeneity between P. n. mongolicus and P. tenggerensis. Thus, we suggest elevating P. n. mongolicus as a full species Pelophylax mongolicus comb. nov., and place P. tenggerensis to be a secondary synonym of P. mongolicus comb. nov.

Soybean cyst nematodes (SCNs) are a significant disease that causes yield loss and reducing seed quality in soybeans (Glycine max). Developing SCN-resistant soybean varieties can minimize the need for insecticide use and reduce yield loss. Cinnamate-4-hydroxylase (C4H) and laccase (Lac) are key enzymes in the lignin synthesis pathway. In this study, SCN stress significantly promoted lignin accumulation in soybean roots and upregulated the expression of lignin signaling pathway genes GmC4H (Glyma.02G236500), GmLac55 (Glyma.13G076900), and GmLac85 (Glyma.20G051900). Using Agrobacterium rhizogenes-mediated transformation, the pNI900 expression vector was introduced into the soybean cultivar Williams 82 to generate GmLac55-overexpressing plants. The overexpression of GmLac55 enhanced soybean roots resistance to SCN and inhibited the further development of J2 larvae. Our study presents a strategy for increasing SCN resistance in soybean through Agrobacterium-mediated targeted mutagenesis of the GmLac55 gene.

Soybean cyst nematode (SCN) development depends on syncytium formation, which requires cell-wall degradation and fusion. Lignin, the main barrier in cell walls, is critical for SCN resistance. 4-Coumarate: CoA ligase (4CL) drives the phenylpropanoid pathway by converting p-coumaric acid to p-coumaroyl-CoA, supplying lignin precursors. Here, resistant cv. Huipizhiheidou accumulated more lignin than susceptible Williams 82 after SCN inoculation. SCN stress induced distinct Gm4CL-family expression profiles across cultivars; Gm4CL3 and Gm4CL4 were markedly upregulated in Huipizhiheidou. Transient expression of Gm4CL3 in tobacco thickened leaf cell walls, implying enhanced wall reinforcement against SCN. Thus, 4CLs, especially Gm4CL3, may promote lignin deposition and secondary wall thickening to strengthen soybean SCN resistance.

Arachis hypogaea. L is a legume of economic importance, which is nodulated by Bradyrhizobium, a slow-growing bacteria. However there is no well characterization of this rhizobia in many areas of China. In the present study, cross-inoculation experiments were performed in cowpea and soybean. The isolated bacteria strains were characterized physiologyically, biochemically and identified through 16S rDNA sequence analysis showing that it belongs to Bradyrhizobium japonicum. The genetic diversity of the seventeen isolated strains were assessed through PCR-RFLP of 16S rDNA and 16S-23S rDNA IGS region. Cross inoculation test indicated that isolates could nodulate cowpea but not soybean. The cluster analysis based on physiological and biochemical characteristics showed the lower correlation between isolates and sites. The isolates were grouped into four clusters based on 16S rDNA gene sequence analysis. Thirteen polymorphisms were variable across all observations in 16S rDNA RFLP and six different IGS types from isolates. The results implies that there was some association between geographical factor and phylogenetic diversity of indigenous Bradyrhizobium isolates.