Wild soybean, the progenitor and close relative of cultivated soybean, has an excellent environmental adaptation ability and abundant resistance genes. Expansins, as a class of cell wall relaxation proteins, have important functions in regulating plant growth and stress resistance. In the present study, we identified a total of 75 members of the expansin family on the basis of recent genomic data published for wild soybean. The predicted results of promoter elements structure showed that wild soybean expansin may be associated with plant hormones, stress responses, and growth. Basal transcriptome data of vegetative organs suggest that the transcription of expansin members has some organ specificity. Meanwhile, the transcripts of some members had strong responses to salt, low temperature and drought stress. We screened and obtained an expansin gene, GsEXPB1, which is transcribed specifically in roots and actively responds to salt stress. The results of A. tumefaciens transient transfection showed that this protein was localized in the cell wall of onion epidermal cells. We initially analyzed the function of GsEXPB1 by a soybean hairy root transformation assay and found that overexpression of GsEXPB1 significantly increased the number of hairy roots, root length, root weight, and the tolerance to salt stress. This research provides a foundation for subsequent studies of expansins in wild soybean.

The NPR1 (nonexpressor of pathogenesis-related genes 1) gene is an activator of the systemic acquisition of resistance (SAR) in plants and is one of the central factors in their response to pathogenic bacterial infestation, playing an important role in plant disease resistance. Potato (Solanum tuberosum) is a crucial non-grain crop that has been extensively studied. However, the identification and analysis of the NPR1-like gene within potato have not been understood well. In this study, a total of six NPR1-like proteins were identified in potato, and phylogenetic analysis showed that the six NPR1-like proteins in Solanum tuberosum could be divided into three major groups with NPR1-related proteins from Arabidopsis thaliana and other plants. Analysis of the exon–intron patterns and protein domains of the six NPR1-like genes from potato showed that the exon–intron patterns and protein domains of the NPR1-like genes belonging to the same Arabidopsis thaliana subfamily were similar. By performing quantitative real-time PCR (qRT-PCR) analysis, we found that six NPR1-like proteins have different expression patterns in different potato tissues. In addition, the expression of three StNPR1 genes was significantly downregulated after being infected by Ralstonia solanacearum (RS), while the difference in the expression of StNPR2/3 was insignificant. We also established potato StNPR1 overexpression lines that showed a significantly increased resistance to R. solanacearum and elevated activities of chitinase, β-1,3-glucanase, and phenylalanine deaminase. Increased peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities, as well as decreased hydrogen peroxide, regulated the dynamic balance of reactive oxygen species (ROS) in the StNPR1 overexpression lines. The transgenic plants activated the expression of the genes associated with the Salicylic acid (SA) defense response but suppressed the expression of the genes associated with Jasmonic acid (JA) signaling. This resulted in resistance to Ralstonia solanacearum.

Universal stress proteins (USPs) play an important regulatory role in responses to abiotic stress. Most of the research related to USPs so far has been conducted on plant models such as Arabidopsis (Arabidopsis thaliana), rice (Oryza sativa L.), and cotton (Gossypium hirsutum L.). The potato (Solanum tuberosum L.) is one of the four major food crops in the world. The potato is susceptible to mechanical damage and infection by pathogenic fungi during transport and storage. Deoxynivalenol (DON) released by Fusarium can seriously degrade the quality of potatoes. As a result, it is of great significance to study the expression pattern of the potato StUSP gene family under abiotic stress conditions. In this study, a total of 108 USP genes were identified from the genome of the Atlantic potato, divided into four subgroups. Based on their genetic structure, the physical and chemical properties of their proteins and other aspects of their biological characteristics are comprehensively analyzed. Collinear analysis showed that the homologous genes of StUSPs and four other representative species (Solanum lycopersicum, Arabidopsis, Oryza sativa L., and Nicotiana attenuata) were highly conserved. The cis-regulatory elements of the StUSPs promoter are involved in plant hormones, environmental stress, mechanical damage, and light response. RNA-seq analysis showed that there are differences in the expression patterns of members of each subgroup under different abiotic stresses. A Weighted Gene Coexpression Network Analysis (WGCNA) of the central gene showed that the differential coexpression gene is mainly involved in the plant–pathogen response process, plant hormone signal transduction, and the biosynthesis process of secondary metabolites. Through qRT-PCR analysis, it was confirmed that StUSP13, StUSP14, StUSP15, and StUSP41 may be important candidate genes involved in the response to adversity stress in potatoes. The results of this study provide a basis for further research on the functional analysis of StUSPs in the response of potatoes to adversity stress.

Expansin is a cell wall relaxant protein that is common in plants and directly or indirectly participates in the whole process of plant root growth, development and morphogenesis. A well-developed root system helps plants to better absorb water and nutrients from the soil while effectively assisting them in resisting osmotic stress, such as salt stress. In this study, we observed and quantified the morphology of the roots of Arabidopsis overexpressing the TaEXPAs gene obtained by the research group in the early stage of development. We combined the bioinformatics analysis results relating to EXPA genes in five plants and identified TaEXPA7-B, a member of the EXPA family closely related to root development in winter wheat. Subcellular localization analysis of the TaEXPA7-B protein showed that it is located in the plant cell wall. In this study, the TaEXPA7-B gene was overexpressed in rice. The results showed that plant height, root length and the number of lateral roots of rice overexpressing the TaEXPA7-B gene were significantly higher than those of the wild type, and the expression of the TaEXPA7-B gene significantly promoted the growth of lateral root primordium and cortical cells. The plants were treated with 250 mM NaCl solution to simulate salt stress. The results showed that the accumulation of osmotic regulators, cell wall-related substances and the antioxidant enzyme activities of the overexpressed plants were higher than those of the wild type, and they had better salt tolerance. This paper discusses the effects of winter wheat expansins in plant root development and salt stress tolerance and provides a theoretical basis and relevant reference for screening high-quality expansin regulating root development and salt stress resistance in winter wheat and its application in crop molecular breeding.

As a type of cell-wall-relaxing protein that is widely present in plants, expansins have been shown to actively participate in the regulation of plant growth and responses to environmental stress. Wild soybeans have long existed in the wild environment and possess abundant resistance gene resources, which hold significant value for the improvement of cultivated soybean germplasm. In our previous study, we found that the wild soybean expansin gene GsEXLB14 is specifically transcribed in roots, and its transcription level significantly increases under salt and drought stress. To further identify the function of GsEXLB14, in this study, we cloned the CDS sequence of this gene. The transcription pattern of GsEXLB14 in the roots of wild soybean under salt and drought stress was analyzed by qRT-PCR. Using an Agrobacterium rhizogenes-mediated genetic transformation, we obtained soybean hairy roots overexpressing GsEXLB14. Under 150 mM NaCl- and 100 mM mannitol-simulated drought stress, the relative growth values of the number, length, and weight of transgenic soybean hairy roots were significantly higher than those of the control group. We obtained the transcriptomes of transgenic and wild-type soybean hairy roots under normal growth conditions and under salt and drought stress through RNA sequencing. A transcriptomic analysis showed that the transcription of genes encoding expansins (EXPB family), peroxidase, H⁺-transporting ATPase, and other genes was significantly upregulated in transgenic hairy roots under salt stress. Under drought stress, the transcription of expansin (EXPB/LB family) genes increased in transgenic hairy roots. In addition, the transcription of genes encoding peroxidases, calcium/calmodulin-dependent protein kinases, and dehydration-responsive proteins increased significantly. The results of qRT-PCR also confirmed that the transcription pattern of the above genes was consistent with the transcriptome. The differences in the transcript levels of the above genes may be the potential reason for the strong tolerance of soybean hairy roots overexpressing the GsEXLB14 gene under salt and drought stress. In conclusion, the expansin GsEXLB14 can be used as a valuable candidate gene for the molecular breeding of soybeans.

Phytophthora infestans poses a serious threat to potato production, storage, and processing. Understanding plant immunity triggered by fungal elicitors is important for the effective control of plant diseases. However, the role of the potato stress response to Fusarium toxin deoxynivalenol (DON)-induced stress is still not fully understood. In this study, the metabolites of DON-treated potato tubers were studied for four time intervals using UPLC-MS/MS. We identified 676 metabolites, and differential accumulation metabolite analysis showed that alkaloids, phenolic acids, and flavonoids were the major differential metabolites that directly determined defense response. Transcriptome data showed that differentially expressed genes (DEGs) were significantly enriched in phenylpropane and flavonoid metabolic pathways. Weighted gene co-expression network analysis (WGCNA) identified many hub genes, some of which modulate plant immune responses. This study is important for understanding the metabolic changes, transcriptional regulation, and physiological responses of active and signaling substances during DON induction, and it will help to design defense strategies against Phytophthora infestans in potato.