In the realm of plant biology, small RNAs (sRNAs) are imperative in the orchestration of gene expression, playing pivotal roles across a spectrum of developmental sequences and responses to environmental stressors. The biosynthetic cascade of sRNAs is characterized by an elaborate network of enzymatic pathways that meticulously process double-stranded RNA (dsRNA) precursors into sRNA molecules, typically 20 to 30 nucleotides in length. These sRNAs, chiefly microRNAs (miRNAs) and small interfering RNAs (siRNAs), are integral in guiding the RNA-induced silencing complex (RISC) to selectively target messenger RNAs (mRNAs) for post-transcriptional modulation. This regulation is achieved either through the targeted cleavage or the suppression of translational efficiency of the mRNAs. In plant development, sRNAs are integral to the modulation of key pathways that govern growth patterns, organ differentiation, and developmental timing. The biogenesis of sRNA itself is a fine-tuned process, beginning with transcription and proceeding through a series of processing steps involving Dicer-like enzymes and RNA-binding proteins. Recent advances in the field have illuminated the complex processes underlying the generation and function of small RNAs (sRNAs), including the identification of new sRNA categories and the clarification of their involvement in the intercommunication among diverse regulatory pathways. This review endeavors to evaluate the contemporary comprehension of sRNA biosynthesis and to underscore the pivotal role these molecules play in directing the intricate performance of plant developmental processes.

The development of soybean (Glycine max) is regulated by the photoperiod, with genes related to photoperiod sensitivity primarily focused on the flowering time. However, their roles in post-flowering reproductive development and the mechanisms by which the photoperiod affects them are not yet determined. In this study, we found that pod formation is sensitive to the photoperiod. Long-day conditions tended to extend the time from flowering to pod formation, and the first wave of flowers tended to fall off. Additionally, the photoperiod affected the pistil morphology; under short-day conditions, the stigma had a curved hook-like structure that facilitated better interaction with the filaments when pollen was released, ultimately influencing the timing of pod formation. Photoperiod-insensitive mutants, lacking E1 family and Evening Complex (EC) genes, showed no difference in the pod formation time under long-day or short-day conditions. Hormone content analysis and transcriptome data analysis indicated that various hormones, reactive oxygen species (ROS) burst pathway signals, and the application of sucrose solution in vitro might influence floral organ abscission.

Background: Soybean (Glycine max (L.) Merr.) is a significant economic oilseed crop, and saline-alkali soils restrict soybean yield. Identifying salt-tolerant genes is a key strategy for enhancing soybean productivity under saline-alkali conditions. The roles of the GmABCB gene family in growth, development, and stress resistance remain incompletely understood. Methods: Bioinformatics approaches were employed to identify and analyze GmABCB genes. A total of 39 GmABCB genes were identified and analyzed in the soybean genome, focusing on their phylogenetic relationships, chromosomal distribution, gene structure, cis-acting elements, evolutionary history, and expression patterns under salt stress. Results: A total of 39 GmABCB genes were identified. These genes are unevenly distributed across the soybean genome, with 21 segmental duplication events identified. Several cis-acting elements associated with abiotic stress responses were identified. Conclusions: The GmABCB gene family likely regulates growth, development, and stress tolerance in soybean.

Summary: Formation of root nodules is a unique hallmark of the symbiotic interaction between legume host plants and rhizobia and is governed by a complex regulatory framework that balances the appropriate orchestration of rhizobial infection and subsequent nodule organogenesis. In contrast to prominent model species such as Medicago truncatula and Lotus japonicus, research on symbiotic signal transduction in the staple‐crop soybean Glycine max remains relatively insufficient. Here, we identified a soybean mutant with ~25% additional root nodules over wild‐type, designated as increased number of nodules 1 (inn1). Through map‐based cloning, INN1 encodes the EARLY FLOWERING 3a (ELF3a) protein component of the soybean Evening Complex, together with LUX1 and LUX2. INN1 is co‐expressed with LUX1 and LUX2 in roots, and knockout of INN1 or knockdown of LUX1 and LUX2 enhances root nodulation. The function of INN1 in negatively regulating nodulation is genetically and biochemically dependent upon LUXs, as the INN1–LUX complex binds to the promoter of the downstream pro‐nodulation target ENOD40, repressing its expression. ELF3a/INN1's repression of root‐nodule formation extends beyond its established roles in diverse above‐ground developmental and physiological processes and offers a theoretical basis for enhancing the biological‐nitrogen fixation capacity of soybean.

Serine acetyltransferase (SAT) is a critical enzyme in the sulfur-assimilation pathway of cysteine, playing an essential role in numerous physiological functions in plants, particularly in their response to environmental stresses. However, the structural characteristics of the soybean SAT gene family remain poorly understood. Members of the soybean SAT gene family were identified using the Hidden Markov Model approach. Bioinformatics tools, such as ExPASy, PlantCARE, MEME, and TBtools-II, were employed to examine the physicochemical properties, cis-regulatory elements, conserved motifs, gene structures, and chromosomal positions of the GmSAT genes. RT-qPCR was conducted to evaluate the expression profiles of GmSAT genes under NaCl-induced stress, identifying genes likely involved in the salt-stress response. A total of ten GmSAT genes were identified in the soybean genome and grouped into three subfamilies. Genes within each subfamily shared notable structural similarities and conserved motifs. Analysis of cis-regulatory elements revealed that the promoters of these genes contain several elements linked to plant growth and stress-related responses. Expression patterns of GmSAT genes varied across different soybean tissues, with GmSAT10 showing higher expression in roots, while GmSAT1 and GmSAT2 had lower expression in the same tissue. Following NaCl treatment, expression levels of seven GmSAT genes were significantly increased in the roots, indicating their potential involvement in the plant’s adaptation to salt stress. GmSAT genes appear to play crucial roles in soybean’s response to salt stress, offering insights that could aid in the development of salt-tolerant soybean varieties.

Glycoside hydrolase family 18 (GH18) proteins can hydrolyze the β-1,4-glycosidic bonds of chitin, which is a common structure component of insect exoskeletons and fungal cell walls. In this study, 36 GH18 genes were identified and subjected to bioinformatic analysis based on the genomic data of Glycine max. They were distributed in 16 out of 20 tested soybean chromosomes. According to the amino acid sequences, they can be further divided into five subclades. Class III chitinases (22 members) and class V chitinases (6 members) are the major two subclades. The amino acid size of soybean GH18 proteins ranges from 173 amino acids (aa) to 820 aa and the molecular weight ranges from 19.46 kDa to 91.01 kDa. From an evolutionary perspective, soybean GH18 genes are closely related to Medicago (17 collinear loci with soybean) and Lotus (23 collinear loci with soybean). Promoter analysis revealed that GH18 genes could be induced by environmental stress, hormones, and embryo development. GmGH18-15, GmGH18-24, and GmGH18-33 were screened out due to their nodulation specific expression and further verified by RT-qPCR. These results provide an elaborate reference for the further characterization of specific GH18 genes, especially during nodule formation in soybean.