Shuilian Chen

To assess the application potential of the Y63-1 strain in soybean varieties other than its capture host, Zhongdou 63 (ZD63), we investigated the response of Zhongdou 41 (ZD41) to Y63-1 inoculation under four levels of NH₄NO₃ in greenhouse and five field trials. Compared to the control group, the increased percentages in nodule number for ZD41 in the greenhouse and field were 8.6% to 145.7% and 18.3% to 323.4%, respectively. The increased percentages of nodule dry weight were 10.5% to 46.7% and 7.9% to 890.3%, respectively. The growth, development, and chlorophyll content of ZD41 were promoted by inoculation with Y63-1 under greenhouse and field conditions. The grain weight per plant of ZD41 was increased by 7.90% to 17.10% in HC-2024, 14.50% in ZMD-2024, and 13.40% in YL-2025-1 compared to the control group. The increased plot yield of ZD41 after inoculation with the Y63-1 strain reached 7.9% in HC-2024 and 10.6% in ZMD-2024. It was concluded that ZD41-Y63-1 symbiosis is suitable for different nitrogen levels and multiple field environments. Our findings provide technical support for the application of Y63-1 in other soybean cultivars and a reference for the identification of symbiotic nitrogen-fixation characteristics of soybean varieties.

Our previous studies identified a new efficient and broad-spectrum rhizobium strain Bradyrhizobium elkanii Y63-1. This study evaluated the symbiotic effects of Y63-1 inoculation on Zhongdou 63 (ZD63) in native environments and under different nitrogen levels. The evaluation of symbiotic effects in native environments was conducted through pot experiments and field trials. Pot experiments were performed in greenhouse using three soil types. Field trials were conducted in three regions with different soil nitrogen levels. The symbiotic effect of soybean ZD63 inoculated with Y63-1 under different nitrogen levels was investigated through pot experiments in greenhouse. The results showed that Y63-1 is more competitive than the indigenous rhizobia of the three soil types in the nodulation of soybean ZD63. The nodulation ability and yield-related traits of soybean ZD63 were improved after inoculation with Y63-1 in the three regions, especially in Hanchuan, where the soil nitrogen level is relatively rich. The symbiotic effect of soybean ZD63 inoculated with Y63-1 in a pot experiment with four levels of N from 0 to 3.75 mmol/L was superior at N 2.81 mmol/L. Our findings provided technical support for the application of Y63-1 in China, and a theoretical basis for increasing the yield potential of soybean through inoculation with highly efficient rhizobia in agricultural production.

The COP9 signalosome (CSN) is a highly conserved eukaryotic protein complex that plays a crucial role in plant growth, development, and stress responses by modulating the ubiquitination pathway. Emerging evidence underscores its significance in plant immunity, where it orchestrates diverse defense mechanisms, including hormone signaling, reactive oxygen species (ROS), homeostasis, and secondary metabolite (SM) biosynthesis. As a key regulator, CSN influences multiple layers of immune responses, such as pattern-triggered immunity (PTI), effector-triggered immunity (ETI), and systemic acquired resistance (SAR). However, the intricate interplay between CSN and immune regulatory networks remains incompletely understood, and a comprehensive model of its mechanistic framework is still lacking. This review systematically consolidates current knowledge on CSN-mediated immune regulation in plant–pathogen interactions and highlights its role in disease resistance.

In a previous study, GmMYB14 overexpressing (GmMYB14-OX) transgenic soybean plants displayed a semi-dwarfism and compact phenotype, which was regulated by the brassinosteroid (BR) pathway. However, the phenotype of GmMYB14-OX plants could be partly rescued after spraying them with exogenous BR. This indicates that other hormones, in addition to BR, also play a role in regulating the architecture of GmMYB14-OX plants. We observed a significant decrease in the content of endogenous indole-3-acetic acid (IAA) in transgenic soybean lines (OX9 and OX12) compared to wild type (WT) plants. The plant height, leaf area, leaf petiole length, and leaf petiole angle of GmMYB14-OX plants could also be partly rescued after applying exogenous IAA for two weeks. Transcriptome sequencing analysis revealed that the expression of many genes within the Aux/IAA gene family underwent alterations in the GmMYB14-OX transgenic soybean plants. Among them, Glyma.02G000500 (GmIAA1) showed the highest expression in GmMYB14-OX plants. Furthermore, the results of electrophoretic mobility shift assay and dual-luciferase reporter indicate that GmMYB14 protein could bind to the promoter of GmIAA1. In summary, a decrease in endogenous IAA content may be one of the factors contributing to the compact and dwarfed architecture of GmMYB14-OX plants. GmMYB14 also acts as a transcriptional activator of GmIAA1 to potentially block IAA effects. Our findings provide a theoretical basis for further investigation of the regulatory mechanism of GmMYB14 on soybean plant architecture.

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi, is one of the most destructive foliar diseases that affect soybeans. Developing resistant cultivars is the most cost-effective, environmentally friendly, and easy strategy for controlling the disease. However, the current understanding of the mechanisms underlying soybean resistance to P. pachyrhizi remains limited, which poses a significant challenge in devising effective control strategies. In this study, comparative transcriptomic profiling using one resistant genotype and one susceptible genotype was performed under infected and control conditions to understand the regulatory network operating between soybean and P. pachyrhizi. RNA-Seq analysis identified a total of 6540 differentially expressed genes (DEGs), which were shared by all four genotypes. The DEGs are involved in defense responses, stress responses, stimulus responses, flavonoid metabolism, and biosynthesis after infection with P. pachyrhizi. A total of 25,377 genes were divided into 33 modules using weighted gene co-expression network analysis (WGCNA). Two modules were significantly associated with pathogen defense. The DEGs were mainly enriched in RNA processing, plant-type hypersensitive response, negative regulation of cell growth, and a programmed cell death process. In conclusion, these results will provide an important resource for mining resistant genes to P. pachyrhizi infection and valuable resources to potentially pyramid quantitative resistance loci for improving soybean germplasm.

Chlorophyll plays an essential role in photosynthetic light harvesting and energy transduction in green tissues of higher plants and is closely related to photosynthesis and crop yield. Identification of transcription factors (TFs) involved in regulating chlorophyll biosynthesis is still limited in soybean (Glycine max), and the previously identified GmGATA58 is suggested to potentially modulate chlorophyll and nitrogen metabolisms, but its complete function is still unknown. In this study, subcellular localization assay showed that GmGATA58 was localized in the nucleus. Histochemical GUS assay and qPCR assay indicated that GmGATA58 was mainly expressed in leaves and responded to nitrogen, light and phytohormone treatments. Overexpression of GmGATA58 in the Arabidopsis thaliana ortholog AtGATA21 (gnc) mutant complemented the greening defect, while overexpression in Arabidopsis wild-type led to increasing chlorophyll content in leaves through up-regulating the expression levels of the large of chlorophyll biosynthetic pathway genes, but suppressing plant growth and yield, although the net photosynthetic rate was slightly improved. Dual-luciferase reporter assay also supported that GmGATA58 activated the transcription activities of three promoters of key chlorophyll biosynthetic genes of soybean in transformed protoplast of Arabidopsis. It is concluded that GmGATA58 played an important role in regulating chlorophyll biosynthesis, but suppressed plant growth and yield in transgenic Arabidopsis.

The plant architecture has significant effects on grain yield of various crops, including soybean (Glycine max), but the knowledge on optimization of plant architecture in order to increase yield potential is still limited. Recently, CRISPR/Cas9 system has revolutionized genome editing, and has been widely utilized to edit the genomes of a diverse range of crop plants. In the present study, we employed the CRISPR/Cas9 system to mutate four genes encoding SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors of the SPL9 family in soybean. These four GmSPL9 genes are negatively regulated by GmmiR156b, a target for the improvement of soybean plant architecture and yields. The soybean Williams 82 was transformed with the binary CRISPR/Cas9 plasmid, assembled with four sgRNA expression cassettes driven by the Arabidopsis thaliana U3 or U6 promoter, targeting different sites of these four SPL9 genes via Agrobacterium tumefaciens-mediated transformation. A 1-bp deletion was detected in one target site of the GmSPL9a and one target site of the GmSPL9b, respectively, by DNA sequencing analysis of two T0-generation plants. T2-generation spl9a and spl9b homozygous single mutants exhibited no obvious phenotype changes; but the T2 double homozygous mutant spl9a/spl9b possessed shorter plastochron length. In T4 generation, higher-order mutant plants carrying various combinations of mutations showed increased node number on the main stem and branch number, consequently increased total node number per plants at different levels. In addition, the expression levels of the examined GmSPL9 genes were higher in the spl9b-1 single mutant than wild-type plants, which might suggest a feedback regulation on the expression of the investigated GmSPL9 genes in soybean. Our results showed that CRISPR/Cas9-mediated targeted mutagenesis of four GmSPL9 genes in different combinations altered plant architecture in soybean. The findings demonstrated that GmSPL9a, GmSPL9b, GmSPL9c and GmSPL9 function as redundant transcription factors in regulating plant architecture in soybean.