Search Results (106)

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. Full article

Disease-suppressive soils confer fitness advantages to plants after a disease outbreak due to the subsequent assembly of protective microbiota in natural environments. However, the role of ecological effects on the assemblage of a protective soil microbiome is largely elusive. In this study, we investigated the composition of parasitic microbes and their relationships with soybean cyst nematodes in suppressive soil. The results showed that parasitic microbial assembly along soybean cyst nematodes was shaped predominantly by the density of soybean cyst nematodes. We also found soybean continuous cropping increased the number of parasitic microbes of soybean cyst nematodes with the order of Ss > Sr > Sc, while it decreased the population of soybean cyst nematodes, resulting in a natural decline in the number of soybean cyst nematodes. These findings indicate that the population of soybean cyst nematodes accumulated parasitic microorganisms against this soil-borne disease under soybean long-term continuous cropping. Moreover, the metabolic activity of cyst parasitic microbes was increased by two years of continuous cropping (Sc) of soybean, and total carbon and total nitrogen of soil were the main impact factors in this short-term continuous cropping for metabolic patterns of the cyst parasitic microbes. In summary, the results highlight that the interaction of plants and disease shape the soil microbiome, recruit a group of disease resistance-inducing microbes, and modulate their beneficial traits to protect the plant. Full article

To identify the key genes conferring resistance to soybean cyst nematode race 4 (SCN4, Heterodera glycines), this study utilized 280 recombinant inbred lines (RILs) derived from the resistant cultivar Huipizhiheidou (HPD) and the susceptible cultivar Jindou23 (JD23). Through phenotypic characterization and a genome-wide association study (GWAS), a genomic region (Gm18:1,223,546–1,782,241) on chromosome 18 was mapped, yielding 14 candidate genes. GmPDH1 was validated as a critical resistance gene using reverse transcription quantitative PCR (RT-qPCR) and Kompetitive Allele Specific PCR (KASP) marker M0526. RT-qPCR revealed that GmPDH1 expression in HPD roots was upregulated 9 days post-inoculation with SCN4 compared to uninoculated controls. KASP genotyping showed that marker M0526 efficiently distinguished between resistant and susceptible plants in natural populations: 71.05% of the resistant accessions exhibited resistant or moderately resistant genotypes, whereas 81.03% of the susceptible accessions showed susceptible or highly susceptible genotypes. Functional validation demonstrated that overexpression of GmPDH1 significantly enhanced SCN4 resistance in the susceptible cultivars JD23 and Jack, whereas CRISPR/Cas9-mediated knockout of GmPDH1 in HPD attenuated its resistance. This study confirmed GmPDH1 as a key gene governing SCN4 resistance and developed an efficient molecular marker, M0526, providing theoretical insights and technical tools for dissecting nematode resistance mechanisms and advancing soybean disease-resistant breeding. Full article

Plant small peptides are critical regulators of various biological processes, including development and stress responses. Polypeptides within the DUF3774 family, known as wound-induced polypeptides (WIPs), have been identified as key players in pattern-triggered immunity (PTI) and defense mechanisms in Arabidopsis. In this study, the genome-wide identification of WIP genes in Glycine max was performed, followed by gene structure correction and validation using second-generation and full-length RNA sequencing data. A total of 31 GmWIP genes were identified and validated, mapped to chromosomes Gm06, Gm12, Gm13, and Gm06_scaffold_301. Phylogenetic analysis grouped these genes into five distinct clusters, with tandem duplication emerging as the primary mechanism for their expansion in the soybean genome. qRT-PCR analysis revealed dynamic and significant changes in GmWIP expression during soybean cyst nematode (SCN) infection in a susceptible soybean cultivar. Remarkably, 90% of the GmWIP genes were downregulated at the early stage of SCN infection (1 dpi), and further corroborated by the pGmWIPs::GUS reporter system. These findings suggest that GmWIP genes may act as regulators in the defense responses of susceptible soybean cultivars, providing a foundation for future functional studies. Full article

This study investigates the proteomic dynamics in tomato cultivars with differing resistance to potato cyst nematodes (PCNs). Cyst-forming nematodes, significant agricultural pests, induce complex molecular responses in host plants, forming syncytia in roots for their nutrition. This research employs mass spectrometry to analyze the proteomes of infected and uninfected roots from susceptible (Moneymaker) and resistant (LA1792 and L10) tomato lines. Over 2800 high-confidence protein hits were identified, revealing significant differences in abundance between susceptible and resistant lines. Notably, resistant lines exhibited a higher number of newly expressed proteins compared to susceptible lines; however, the proportion of induced and suppressed proteins was strongly genotype-dependent. Gene ontology (GO) analysis highlighted that nematode infection in susceptible line significantly regulates many defense-related proteins, particularly those involved in oxidative stress, with a similar number being upregulated and downregulated. Some GO terms enriched among nematode-regulated proteins also indicate the involvement of programmed cell death (PCD)-related processes. The susceptible line exhibited a prevalence of downregulated proteins, among which defense associated GO terms were significantly overrepresented. Four proteins (APY2, NIA2, GABA-T, and AATP1) potentially crucial for nematode parasitism were identified and their Arabidopsis orthologs were studied. Mutant Arabidopsis lines showed altered nematode resistance, supporting the involvement of these proteins in plant defense. This study highlights the complexity of host-nematode interactions and emphasizes the importance of proteomic analyses in identifying key factors and understanding plant defense mechanisms. Full article

Soybean is crucial to food processing and agricultural output. However, pests and diseases can easily impact soybeans, reducing their production. Soybean cyst nematode (SCN) is a soilborne pathogen that has a large geographic range, a long lifespan, and the potential to inflict substantial harm to the soybean industry. Persistent use of major resistance genes leads to a progressive loss of resistance; therefore, continuous identification of new soybean strains and genes is essential for continued sustainable soybean production. In this research, the SCN-resistant and SCN-sensitive germplasm DN-L10 and Heinong 37 were inoculated with SCN 3. After stress treatment, the stressed roots were collected for RNA-Seq analysis. The sequencing results screened out the differentially expressed gene GmbHLH18. The GmbHLH18 gene was cloned, and the overexpression vector pCAMBIA3300-GmbHLH18 was constructed. Agrobacterium infected soybean hairy roots and genetically modified the roots of DN50 soybeans, and transgenic root seedlings were obtained. The transgenically identified root seedlings were transplanted in soil infested with SCN 3, and resistance to root nematodes was determined by magenta staining. The secondary and tertiary structures of the protein, phosphorylation sites, as well as the hydrophilicity related to the GmbHLH18 gene were analyzed. Subsequently, the recombinant subcellular localization vector pCAMBIA1302-GmbHLH18 was employed. Agrobacterium was injected into tobacco leaves, and organelle-specific expression was observed. Finally, stress resistance-related indexes of the roots of overexpressing plants and WT plants under SCN 3 stress were measured. The results showed that overexpression and subcellular localization vectors were successfully constructed and transformed into Agrobacterium K599 and GV3101, respectively. The encoded protein had 1149 amino acids, a molecular weight of 95.76 kDa, an isoelectric point of 5.04, 60 phosphorylation sites, a tertiary structure of a-helix (36.39%), random coil (53.40%), extended chain (8.64%), and corner (1.57%), and was hydrophilic. The protein that the gene encoded was a nuclear-localized protein, according to the results of subcellular localization analysis. Moreover, the Agrobacterium-induced hairy root test revealed that the number of overexpressed pCAMBIA3300-GmbHLH18 transgenic roots in the unit area of DN50 was substantially lower than in the control group, which at first suggested that the gene had partial resistance to SCN 3. Stress resistance-related indexes suggest that the contents of POD, SOD, and proline in the overexpressing root significantly increase after SCN 3 stress, demonstrating that this gene can enhance the plant’s resistance to the SCN 3 pathogen. Future research could focus on further elucidating the molecular mechanism underlying the gene’s resistance to SCN 3 and exploring its potential application in breeding soybean varieties with enhanced resistance. Full article

Rhizosphere microbes, particularly bacteria, are essential for controlling plant-parasitic nematodes (PPNs) through various mechanisms. However, the plant’s age and the genetic composition of nematode populations can significantly influence the inhibitory effectiveness of these microbes against the beet cyst nematode Heterodera schachtii. In this study, rhizosphere microbes were isolated from 39-day-old and 69-day-old resistant oilseed radish plants to evaluate their impact on the penetration of the second-stage juveniles (J2s) originating from four genetically distinct H. schachtii populations. The suppression of J2s penetration by the attached microbes varied across the nematode populations, which displayed differing levels of aggressiveness toward the resistant oilseed radish. Furthermore, differences in the alpha and beta diversity of rhizosphere bacteria were observed between the 39-day-old and 69-day-old plants, leading to variations in the bacterial attachment among the four nematode populations. In summary, the effectiveness of resistant catch crops against H. schachtii is influenced by the pathogenicity of the nematode populations and their interactions with the rhizosphere microbial community shaped by the plant’s age. Full article

Cyst nematodes remain a major threat to global agricultural production, causing huge losses. To understand the parasitism of the cyst nematodes Heterodera trifolii (HT) and Heterodera schachtii (HS), we constructed whole-genome assemblies using short- and long-read sequencing technologies. The nematode genomes were 379 Mb and 183 Mb in size, with the integrated gene models predicting 40,186 and 18,227 genes in HT and HS, respectively. We found more than half of the genes predicted in HT (64.7%) and HS (53.2%) were collinear to their nearest neighbor H. glycines (HG). Large-scale duplication patterns in HT and segmental duplications of more than half of the orthologous genes indicate that the genome of HT is polyploid in nature. Functional analysis of the genes indicated that 65.6% of the HG genes existed within the HT genome. Most abundant genes in HT and HS were involved in gene regulation, DNA integration, and chemotaxis. Differentially expressed genes showed upregulation of cuticle structural constituent genes during egg and female stages and cytoskeletal motor activity-related genes in juvenile stage 2 (J2). Horizontal gene transfer analyses identified four new vitamin biosynthesis genes, pdxK, pdxH, pdxS, and fabG, of bacterial origin, to be first reported in HT and HS. Mitogenomes of HT, HS, and HG showed similar structure, composition, and codon usage. However, rates of substitution of bases in the gene nad4l were significantly different between HT and HS. The described genomes, transcriptomes, and mitogenomes of plant-parasitic nematodes HT and HS are potential bio-resources used to identify several strategies of control of the nematode. Full article

Background/Objectives: Heterodera avenae is a highly significant plant-parasitic nematode, causing severe economic losses to global crop production each year. Trichoderma species have been found to parasitize nematodes and control them by producing enzymes that degrade eggshells. The T. longibrachiatum T6 (T6) strain has been demonstrated the parasitic and lethal effects on H. avenae cysts and eggs, associated with the increased serine protease activity and trypsin-like serine protease gene (PRA1) expression. Methods: Our present study aimed to purify the recombinant PRA1 protease through a prokaryotic expression system and identify its nematicidal activity. Results: The recombinant PRA1 protease was identified as S1 family trypsin-like serine protease, with a molecular weight of 43.16 kDa. The purified soluble protease exhibited the optimal activity at 35 °C and pH 8.0, and also demonstrating higher hydrolytic ability toward casein and skimmed milk. Meanwhile, the Ca²⁺ and Mg²⁺ enhanced its activity, while the inhibitor PMSF significantly reduced it. The contents of H. avenae eggs leaked out after treatment with the recombinant PRA1 protease, with egg hatching inhibition and relative hatching inhibition rates at 70.60% and 66.58%, respectively. In contrast, there was no sign of content dissolution, and embryos developed normally in the control group. Conclusions: Our present study revealed that the PRA1 protease of T6 strain has a lethal effect on H. avenae eggs, which providing a theoretical basis for developing biocontrol agents to control nematodes. Full article

Cyst nematodes are obligate parasitic nematodes found in the fields of many cultivated crops. These nematodes, which have great economic importance, pose a threat to food security, though they are frequently ignored or misdiagnosed as pests because of covert parasitism. A cyst nematode population parasitizing on Artemisia lavandulaefolia DC., one of the traditional Chinese medicines was collected in Gansu Province. The species was diagnosed using integrative taxonomy and molecular approaches. The cyst population is spherical or lemon-shaped, light brown or dark brown in color, with a long neck and a protruding vulval cone. The stylet of the second-stage juvenile is strong, and the front end of the ball at the base of the stylet is concave; the median bulb and excretory pore are prominent; the tail is blunt and circular, and the transparent tail is usually shorter than the stylet. A phylogenetic analysis was carried out using the internal transcribed spacer (ITS) and 28S genes of ribosomal DNA, which further confirmed the presence of Cactodera chenopodiae. According to our literature review, this is the first report on C. chenopodiae in Compositae. By following this research, we can better understand the challenges posed by A. lavandulaefolia DC. and develop effective strategies for managing its spread and impacts. This will help to protect vulnerable ecosystems and ensure the sustainability of agricultural and forestry activities in affected areas. Full article

This study evaluated nematodes as an alternative to live Artemia when provided in a co-feeding regime to Pacific white shrimp (Penaeus vannamei) post-larvae (PL) reared in a biofloc nursery system. A 20-day experiment employing PL₁₁ was performed for an evaluation of four dietary groups: control [C] (fed exclusively with a dry commercial feed); artificial Artemia [AA] (dry feed composed of extracted and processed Artemia cysts and dry commercial feed); live Artemia and dry commercial feed [LA]; and nematodes and dry commercial feed [N] (Panagrolaimus sp. dry nematodes). The diets were provided twice a day, with the remaining six feed provisions being a commercial dry feed for all experimental groups. A biofloc system was chosen as it offers a potentially sustainable approach to intensive shrimp farming. Alkalinity and pH in the [N] group were significantly higher in the last 5 days of the experiment (p < 0.05), likely causing the significantly lower nitrite levels observed in that same group (p < 0.05). Total and volatile suspended solids were significantly lower in the two live feed groups when compared with [C] and [AA] (p < 0.05). Although PL fed the dry diets exhibited higher growth rates (p < 0.05), the [N] and [LA] groups presented significantly higher final survivals (p < 0.05). No differences were found for survival after a salinity stress test (p ≥ 0.05). These results suggest that nematodes can successfully substitute Artemia in a co-feeding regime for P. vannamei PL reared in biofloc nursery systems. Full article

Plant pathogenic nematodes play an important role in crop production and are difficult to control. One of them is Heterodera schachtii—a cyst nematode, pathogenic to sugar beet. Nature suggests a natural way to resolve this problem by using nematode-trapping fungi, one of which is Pleurotus ostreatus. It is one of the most widespread mushrooms in the world. It is a valuable and widely cultivated edible mushroom with nematocidal properties. The mycelium of this mushroom produces toxin droplets that paralyze nematodes, after which the nematodes become infected with the hyphae filament, resulting in their death. This feature can be put to practical use as a natural nematocidal agent. In this paper, we have described studies on the variability of the nematocidal properties in the progeny of three wild strains of P. ostreatus (Po1, Po2, Po4), obtained by crossing dikaryons with monokaryons (Buller phenomenon). The toxicity of mycelium was tested against the model organism Caenorhabditis elegans and against sugar beet pest—H. schachtii. The results of the study allowed the selection of the progeny heterokaryotic mycelia with the best parameters useful for in vitro control of both nematodes. They differed in the activity against C. elegans and H. schachtii, and in the toxic knobs production. The results indicated that the progeny of the Po1 strain presented a good ability to produce hyphal knobs in the presence of C. elegans, and progenies of the Po4 strain presented good quality of growth in preferred temperatures (10–25 °C). Three strains Po1 5dix27, Po2 20dix21, and Po4 2dix1, as well as a maternal strain Po4 controlled H. schachtii by entwining cysts better than other strains. These strains were moderately effective against C. elegans. Strains Po2 15dix17, Po4 1dix18, and Po4 1dix30 may be considered good controlling isolates against both tested organisms. The results of the research also clearly suggest that the killing properties of P. ostreatus mycelia should not be assessed only by their ability to produce toxic hyphal knobs. Their nematocidal properties also depend on other mechanisms developed by mycelia, which is observed as the lethality of nematodes. The results of this research will lead to a natural way to protect plants against nematodes. The research also proved the nematocidal properties of the wild strains to reduce the H. schachtii population in the soil. Full article

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, 1952, is one of the most destructive plant-parasitic nematodes in soybean production worldwide. The use of resistant soybean is the most effective alternative for its management. However, SCN-resistant soybean cultivars with increased yield and favorable agronomic traits remain limited in the market. Here, we developed a new SCN-resistant soybean cultivar Nongqing 28 from the cross of the female parent cultivar An 02-318 and a male parent line F2 (Hei 99-980 × America Xiaoheidou). Resistance evaluation suggested that Nongqing 28 displayed stable resistance to SCN race 3 in pot assays and the 5-year field experiments, including inhibition of SCN development and reduction in female and cyst numbers. The average yields of Nongqing 28 were 2593 kg/ha and 2660 kg/ha in the 2-year regional trails and the 1-year production trials, with a yield increase of 6.2% and 8.1% compared with the local cultivar Nengfeng 18, respectively. The average seed fat contents in Nongqing 28 reached 21.26%. Additionally, RNA-seq analysis revealed that the resistance of Nongqing 28 to SCN infection is involved in pathogen perception and defense activation, such as reactive oxygen species burst, calcium-mediated defense signaling, hormonal signaling, the MAPK signaling cascade, and phenylpropanoid biosynthesis. In summary, this study provides a detailed characterization of a novel SCN-resistant soybean cultivar with high oil and yield potential. Full article

Serine protease is an extracellular protease secreted by biocontrol fungi that can effectively control nematode diseases by degrading nematode eggshells and enhancing plant resistance. Trichoderma longibrachiatum T6, an important biocontrol fungus, has been demonstrated to effectively parasitize and degrade Heterodera avenae cysts, eggs, and second-stage juveniles (J2s). However, the genes that encoding serine protease and their functions in T. longibrachiatum T6 have not been thoroughly investigated. In this study, we successfully cloned and sequenced the serine protease gene TlSP1 in T. longibrachiatum T6. Our results revealed that the expression level of the TlSP1 gene was induced and significantly increased in T. longibrachiatum T6 after inoculation with H. avenae cysts. The full-length sequence of the coding region (CDS) of TlSP1 gene was 1230 bp and encoded a protein consisting of 409 amino acids. Upon the transformation of the TlSP1 gene into Pichia pastoris X33, the purified recombinant TlSP1 protein exhibited optimal activity at a temperature of 50 °C and pH 8.0. Following 4–10-day of treatment with the purified recombinant TlSP1 protein, the eggshells and content were dissolved and exuded. The number of nematodes invading wheat roots was reduced by 38.43% in the group treated with both TlSP1 and eggs on one side (P1+N) compared to the control group, while the number of nematodes invading wheat roots was reduced by 30.4% in the TlSP1 and eggs two-sided treatment group (P1/N). Furthermore, both the P1+N and P1/N treatments significantly upregulated genes associated with defense enzymes (TaPAL, TaCAT, TaSOD, and TaPOD), genes involved in the lignin synthesis pathway (TaC4H, Ta4CL2, TaCAD1, and TaCAD12), and salicylic acid (SA)-responsive genes (TaNPR1, TaPR1, and TaPR2) and led to the high expression of jasmonic acid (JA)-responsive genes (TaPR4, TaOPR3, and TaAOS2). This study has highlighted the significant role of the TlSP1 gene in facilitating H. avenae eggshells’ dissolution, preventing nematode invasion in the host plant, and boosting plant resistance in wheat. Full article

The cereal cyst nematode (Heterodera latipons) is becoming an economically important species in global cereal production as it is being identified in many new cereal cultivated areas and causes significant losses. Consequently, understanding its biology becomes crucial for researchers in identifying its vulnerabilities and implementing effective control measures. In the current study, different morphological and biochemical changes of H. latipons cysts containing eggs with infective juveniles from a barley field in Jordan were studied during the summer of 2021, at two sample dates. The first, at the harvest of the cereal crop (June 2021), when the infective second-stage juveniles (J2s) were initiating diapause, and the second, before planting the sequent cereal crop (late October 2021), when the J2s were ending diapause. The studied population was characterized morphologically and molecularly, showing 98.4% molecular similarity to both JOD from Jordan and Syrian “300” isolates of H. latipons. The obtained results and observations revealed that there were dramatic changes in all the investigated features of the cysts and eggs they contained. Morphological changes such as cyst color, sub-crystalline layer, and thickness of the rigid eggshell wall were observed. A slight change in the emergence time of J2s from cysts was observed without any difference in the number of emerged J2s. The results of biochemical changes showed that the total contents of carbohydrates, glycogen, trehalose, glycerol, and protein were higher in cysts collected in October when compared to those cysts collected in June. The SDS-PAGE pattern indicated the presence of a protein with the size of ca. 100 kDa in both sampling dates, whereas another protein (ca. 20 kDa) was present only in the cysts of October. Furthermore, the expression of trehalase (tre) gene was detected only in H. latipons collected in October. The outcomes of this study provide new helpful information that elucidates diapause in H. latipons and may be used for the implementation of new management strategies of cyst nematodes. Full article