MicroRNAs play crucial roles in plant defense responses. However, the underlying mechanism by which miR398b contributes to soybean responses to soybean cyst nematode (Heterodera glycines) remains elusive. In this study, by using Agrobacterium rhizogenes-mediated transformation of soybean hairy roots, we observed that miR398b and target genes GmCCS and GmCSD1b played vital functions in soybean-H. glycines interaction. The study revealed that the abundance of miR398b was downregulated by H. glycines infection, and overexpression of miR398b enhanced the susceptibility of soybean to H. glycines. Conversely, silencing of miR398b improved soybean resistance to H. glycines. Detection assays revealed that miR398b rapidly senses stress-induced reactive oxygen species, leading to the repression of target genes GmCCS and GmCSD1b and regulating the accumulation of plant defense genes against nematode infection. Moreover, exogenous synthetic ds-miR398b enhanced soybean sensitivity to H. glycines by modulating H2O2 and O2- levels. Functional analysis demonstrated that overexpression of GmCCS and GmCSD1b in soybean enhanced resistance to H. glycines. RNA interference-mediated repression of GmCCS and GmCSD1b in soybean increased susceptibility to H. glycines. RNA sequencing revealed that a majority of differentially expressed genes in overexpressed GmCCS were associated with oxidative stress. Overall, the results indicate that miR398b targets superoxide dismutase genes, which negatively regulate soybean resistance to H. glycines via modulating reactive oxygen species levels and defense signals.

Pathogen-secreted polygalacturonases (PGs) alter plant cell wall structure by cleaving the α-(1 → 4) linkages between D-galacturonic acid residues in homogalacturonan (HG), macerating the cell wall, facilitating infection. Plant PG inhibiting proteins (PGIPs) disengage pathogen PGs, impairing infection. The soybean cyst nematode, Heterodera glycines, obligate root parasite produces secretions, generating a multinucleate nurse cell called a syncytium, a byproduct of the merged cytoplasm of 200-250 root cells, occurring through cell wall maceration. The common cytoplasmic pool, surrounded by an intact plasma membrane, provides a source from which H. glycines derives nourishment but without killing the parasitized cell during a susceptible reaction. The syncytium is also the site of a naturally-occurring defense response that happens in specific G. max genotypes. Transcriptomic analyses of RNA isolated from the syncytium undergoing the process of defense have identified that one of the 11 G. max PGIPs, GmPGIP11, is expressed during defense. Functional transgenic analyses show roots undergoing GmPGIP11 overexpression (OE) experience an increase in its relative transcript abundance (RTA) as compared to the ribosomal protein 21 (GmRPS21) control, leading to a decrease in H. glycines parasitism as compared to the overexpression control. The GmPGIP11 undergoing RNAi experiences a decrease in its RTA as compared to the GmRPS21 control with transgenic roots experiencing an increase in H. glycines parasitism as compared to the RNAi control. Pathogen associated molecular pattern (PAMP) triggered immunity (PTI) and effector triggered immunity (ETI) components are shown to influence GmPGIP11 expression while numerous agricultural crops are shown to have homologs.

The prevalence of Heterodera glycines and other cyst and vermiform genera was determined from 8,009 soil samples over two decades. Prevalence of cyst nematodes for farms increased from 16% in 1998 to 1999, reaching a peak of 40%, with marked differences among Wisconsin\'s nine agricultural districts in how much the odds of a positive test increased. Estimates at the sample scale also increased over time but peaked at 29%. Assay of all nematodes beginning in 2012 showed Pratylenchus, Helicotylenchus, and Xiphinema to be more prevalent in Wisconsin soybean fields than cyst nematodes. Prevalence estimates for Pratylenchus and Helicotylenchus for soybean and rotation crops ranged from 76 to 89% and 58 to 83%, respectively. Species identification of Pratylenchus from a subset of the samples revealed six species. The majority of cyst-positive samples were infested with Pratylenchus, and count data showed that the number of cyst eggs and juveniles per 100 cm3 soil was 60% lower in samples positive for Pratylenchus. The influence was reciprocal, as Pratylenchus population densities were 41% lower in samples positive for cyst nematodes, suggesting a competitive interaction. The Wisconsin soybean nematode testing program provides a useful model for estimating nematode prevalence using citizen-based surveys.

Unraveling the intricacies of soybean cyst nematode (Heterodera glycines) race 4 resistance and susceptibility in soybean breeding lines-11-452 (highly resistant) and Dongsheng1 (DS1, highly susceptible)-was the focal point of this study. Employing cutting-edge N6-methyladenosine (m6A) and RNA sequencing techniques, we delved into the impact of m6A modification on gene expression and plant defense responses. Through the evaluation of nematode development in both resistant and susceptible roots, a pivotal time point (3 days postinoculation) for m6A methylation sequencing was identified. Our sequencing data exhibited robust statistics, successful soybean genome mapping, and prevalent m6A peak distributions, primarily in the 3\' untranslated region and stop codon regions. Analysis of differential methylation peaks and differentially expressed genes revealed distinctive patterns between resistant and susceptible genotypes. In the highly resistant line (11-452), key resistance and defense-associated genes displayed increased expression coupled with inhibited methylation, encompassing crucial players such as R genes, receptor kinases, and transcription factors. Conversely, the highly susceptible DS1 line exhibited heightened expression correlated with decreased methylation in genes linked to susceptibility pathways, including Mildew Locus O-like proteins and regulatory elements affecting defense mechanisms. Genome-wide assessments, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses, and differential methylation peak/differentially expressed gene overlap emphasized the intricate interplay of m6A modifications, alternative splicing, microRNA, and gene regulation in plant defense. Protein-protein interaction networks illuminated defense-pivotal genes, delineating divergent mechanisms in resistant and susceptible responses. This study sheds light on the dynamic correlation between methylation, splicing, and gene expression, providing profound insights into plant responses to nematode infection.

In an investigation of diseases from plant-parasitizing nematodes in Henan Province, a cyst nematode was found on tobacco roots and in rhizosphere soil. We identified this strain as a new cyst nematode subspecies, Heterodera glycines sbsp.n. tabacum. The cysts and second-stage juveniles (J2s) parasitizing Henan tobacco were larger than those of H. glycines. A single 345-bp fragment was amplified from H. glycines sbsp.n. tabacum, whereas the 345- and 181-bp fragments were amplified from the soybean cyst nematode. Thus, H. glycines sbsp.n. tabacum was distinct from H. glycines. There were base transversions at 504 sites and base transitions at 560, 858, 920, and 921 sites in the rDNA-ITS sequences of H. glycines sbsp.n. tabacum compared with H. glycines, and there were base transitions at 41, 275, 278, and 380 sites in the mtDNA-COI sequences. In the phylogenetic tree based on the rDNA-ITS and mtDNA-COI regions, H. glycines sbsp.n. tabacum was clustered on a single branch. Based on the randomly amplified polymorphic DNA (RAPD) technique, sequence characterized amplified region (SCAR)-PCR primers were designed. A single 1,113-bp fragment was amplified by specific primers (HtF1/HtR1) from H. glycines sbsp.n. tabacum, while no fragments were obtained from H. glycines. The H. glycines sbsp.n. tabacum can infect soybean plants but cannot complete its life cycle on soybean. Eleven tested tobacco cultivars were infected, with an average reproduction factor (Rf) of 9.74 and a maximum of 64.2 in \'K326\'. The cumulative egg hatching rate of H. glycines sbsp.n. tabacum in the presence of tobacco root exudates was 42.6% at 32 days posthatching, which was significantly greater than that in the presence of soybean root exudates (30.3%) or sterile water (33.1%). In summary, the cyst nematode population parasitizing Henan tobacco was identified as a new subspecies, H. glycines sbsp.n. tabacum.

Microbial communities play an important role in the growth and development of plants, including plant immunity and the decomposition of complex substances into absorbable nutrients. Hence, utilizing beneficial microbes becomes a promising strategy for the optimization of plant growth. The objective of this research was to explore the root bacterial profile across different soybean genotypes and the change in the microbial community under soybean cyst nematode (SCN) infection in greenhouse conditions using 16S rRNA sequencing. Soybean genotypes with soybean cyst nematode (SCN) susceptible and resistant phenotypes were grown under field and greenhouse conditions. Bulked soil, rhizosphere, and root samples were collected from each replicate. Sequencing of the bacterial 16S gene indicated that the bacterial profile of soybean root and soil samples partially overlapped but also contained different communities. The bacterial phyla Proteobacteria, Actinobacteria, and Bacteroidetes dominate the soybean root-enriched microbiota. The structure of bacteria was significantly affected by sample year (field) or time point (greenhouse). In addition, the host genotype had a small but significant effect on the diversity of the root microbiome under SCN pressure in the greenhouse test. These differences may potentially represent beneficial bacteria or secondary effects related to SCN resistance.

Soybeans, one of the most valuable crops worldwide, are annually decimated by the soybean cyst nematode (SCN), Heterodera glycines, resulting in massive losses in soybean yields and economic revenue. Conventional agricultural pesticides are generally effective in the short term; however, they pose growing threats to human and environmental health; therefore, alternative SCN management strategies are urgently needed. Preliminary findings show that phenolic acids are significantly induced during SCN infection and exhibit effective nematocidal activities in vitro. However, it is unclear whether these effects occur in planta or elicit any negative effects on plant growth traits. Here, we employed a phytochemical-based seed coating application on soybean seeds using phenolic acid derivatives (4HBD; 2,3DHBA) at variable concentrations and examined SCN inhibition against two SCN types. Moreover, we also examined plant growth traits under non-infected or SCN infected conditions. Notably, 2,3DHBA significantly inhibited SCN abundance in Race 2-infected plants with increasingly higher chemical doses. Interestingly, neither compound negatively affected soybean growth traits in control or SCN-infected plants. Our findings suggest that a phytochemical-based approach could offer an effective, more environmentally friendly solution to facilitate current SCN management strategies and fast-track the development of biopesticides to sustainably manage devastating pests such as SCN.

The plant cell wall structure can be altered by pathogen-secreted polygalacturonases (PGs) that cleave the α-(1→4) linkages occurring between D-galacturonic acid residues in homogalacturonan. The activity of the PGs leads to cell wall maceration, facilitating infection. Plant PG inhibiting proteins (PGIPs) impede pathogen PGs, impairing infection and leading to the ability of the plant to resist infection. Analyses show the Glycine max PGIP11 (GmPGIP11) is expressed within a root cell that is parasitized by the pathogenic nematode Heterodera glycines, the soybean cyst nematode (SCN), but while undergoing a defence response that leads to its demise. Transgenic experiments show GmPGIP11 overexpression leads to a successful defence response, while the overexpression of a related G. max PGIP, GmPGIP1 does not, indicating a level of specificity. The analyses presented here have identified PGIPs from 51 additional studied proteomes, many of agricultural importance. The analyses include the computational identification of signal peptides and their cleavage sites, O-, and N-glycosylation. Artificial intelligence analyses determine the location where the processed protein localize. The identified PGIPs are presented as a tool base from which functional transgenics can be performed to determine whether they may have a role in plant-pathogen interactions.

We previously reported soybean fields double-cropped with winter wheat having reduced soybean cyst nematode (SCN) (Heterodera glycines) counts compared to fallow. A follow-up metagenomics study identified several fungal and bacterial taxa enriched in wheat fields, and some were reported to parasitize SCN. Knowing that phytocompounds with potential nematicidal activity are released via wheat roots and stubble, we implemented a dichloromethane-based extraction method and a gas chromatography-mass spectrometry (GCMS) system to investigate soil chemical profiles of samples collected from these fields and review the potential nematicidal activity of compounds with higher concentration in double cropping fields. 51 compounds were detected during the GCMS analysis, eight with unknown identification. Several compounds, including multiple fatty acids, had larger relative peak areas when double-cropped, compared to fallow samples. This study, along with our previously published one, provided a better understanding of the mechanisms that govern the effect of wheat on SCN populations. Rather than driven by a single mechanism, the suppression of SCN in soybean fields double-cropped with winter wheat was potentially linked to enriched microbial communities, increased populations of beneficial organisms, and higher concentrations of chemicals with potential nematicidal activity. To our knowledge, this is the first study using GCMS to characterize soil chemical profiles in soybean fields double-cropped with winter wheat regarding the suppression of SCN populations.

The soybean cyst nematode (SCN - Heterodera glycines) is one of the most damaging pests to the cultivated soybean worldwide. Using a wide array of stylet-secreted effector proteins, this nematode can restructure its host cells into a complex and highly active feeding structure called the syncytium. Tight regulation of these proteins is thought to be essential to the successful formation of this syncytium. To date, multiple mechanisms have been proposed to regulate the expression of these proteins including through post-transcriptional regulation. MicroRNAs (miRNAs) are a class of small, roughly 22-nucleotide-long, non-coding RNA shown to regulate gene expression through its interaction with the 3\' untranslated region of genes. These same small RNAs have also been hypothesized to be able to cross over kingdom barriers and regulate genes in other species in a process called cross-kingdom interactions. In this study, we characterized the miRNome of the SCN via sequencing of small-RNAs isolated from whole nematodes and exosomes representing all developmental stages. We identified 121 miRNA loci encoding 96 distinct miRNA families including multiple lineage- and species-specific candidates. Using a combination of plant- and animal-specific miRNA target predictors, we generated a unique repertoire of miRNA:mRNA interacting partners in the nematode and its host plant leading to the identification of a set of nine probable cross-kingdom miRNA candidates.