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Developing control measures of plant-parasitic nematodes (PPNs) rank high as they cause big crop losses globally. The growing awareness of numerous unsafe chemical nematicides and the defects found in their alternatives are calling for rational molecular control of the nematodes. This control focuses on using genetically based plant resistance and exploiting molecular mechanisms underlying plant–nematode interactions. Rapid and significant advances in molecular techniques such as high-quality genome sequencing, interfering RNA (RNAi) and gene editing can offer a better grasp of these interactions. Efficient tools and resources emanating from such interactions are highlighted herein while issues in using them are summarized. Their revision clearly indicates the dire need to further upgrade knowledge about the mechanisms involved in host-specific susceptibility/resistance mediated by PPN effectors, resistance genes, or quantitative trait loci to boost their effective and sustainable use in economically important plant species. Therefore, it is suggested herein to employ the impacts of these techniques on a case-by-case basis. This will allow us to track and optimize PPN control according to the actual variables. It would enable us to precisely fix the factors governing the gene functions and expressions and combine them with other PPN control tactics into integrated management.

1. The activity and spread of exotic earthworms often are spatially correlated with N deposition because both arise from human activities. Exotic earthworms, in turn, can also greatly affect soil abiotic and biotic properties, as well as related ecological processes. Previous studies showed, for example, that earthworms can counteract the detrimental effects of plant-feeding nematodes on plant growth. However, potential interactive effects of N deposition and exotic earthworms on ecosystems are poorly understood. 2. We explored the changes in density of plant-feeding nematodes in response to the presence of exotic earthworms, and whether these changes are altered by elevated N deposition in a two-factorial field mesocosm experiment at the Heshan National Field Research Station of Forest Ecosystem, in southern China. 3. Our results show that earthworm addition marginally significantly increased the density of exotic earthworms and significantly increased the mass of earthworm casts. The total density of plant-feeding nematodes was not significantly affected by exotic earthworms or N deposition. However, exotic earthworms tended to increase the density of plant-feeding nematode taxa that are less detrimental to plant growth (r-strategists), while they significantly reduced the density of more harmful plant-feeding nematodes (K-strategists). Importantly, these earthworm effects were restricted to the ambient N deposition treatment, and elevated N deposition cancelled out the earthworm effect. Although exotic earthworms and N deposition interactively altered foliar N : P ratio in the target tree species, this did not result in significant changes in shoot and root biomass in the short term. 4. Overall, our study indicates that N deposition can cancel out exotic earthworm-induced reductions in the density of harmful plant-feeding nematodes. These results suggest that anthropogenic N deposition can alter biotic interactions between exotic and native soil organisms with potential implications for ecosystem functioning.

Plant-parasitic nematodes were found in 4 of the 12 clades of phylum Nematoda. These nematodes in different clades may have originated independently from their free-living fungivorous ancestors. However, the exact evolutionary process of these parasites is unclear. Here, we sequenced the genome sequence of a migratory plant nematode, Ditylenchus destructor. We performed comparative genomics among the free-living nematode, Caenorhabditis elegans and all the plant nematodes with genome sequences available. We found that, compared with C. elegans, the core developmental control processes underwent heavy reduction, though most signal transduction pathways were conserved. We also found D. destructor contained more homologies of the key genes in the above processes than the other plant nematodes. We suggest that Ditylenchus spp. may be an intermediate evolutionary history stage from free-living nematodes that feed on fungi to obligate plant-parasitic nematodes. Based on the facts that D. destructor can feed on fungi and has a relatively short life cycle, and that it has similar features to both C. elegans and sedentary plant-parasitic nematodes from clade 12, we propose it as a new model to study the biology, biocontrol of plant nematodes and the interaction between nematodes and plants.

Background and aims Plant parasitic nematodes (PPNs) are among the most important pests in agriculture. Chemical inputs are widely used for their control; however, the negative impact of these agrochemicals on environmental and human health is a current concern. Biological control and interventions on rhizosphere signaling are promising ecofriendly alternatives for managing these pests in the field. Nevertheless, the molecular mechanisms involved in plant-PPN interaction need to be unraveled in order to develop appropriate management strategies. Strigolactones (SLs) are phytohormones that are exuded from roots, acting as signaling molecules in the rhizosphere. They are important cues in the establishment of arbuscular mycorrhizal and Rhizobium -legume symbioses. Recently, it has been shown that SLs can also affect the interaction between plants and certain PPN species; however, data are scarce and ambiguous. Some studies propose that SLs positively regulate PPN species performance acting as attractants to roots, or by inhibiting plant defense responses. On the contrary, other studies suggest that SLs could negatively regulate PPN performance by reducing abscisic acid, or by promoting plant interactions with beneficial soil microorganisms. In the present Opinion paper, we discuss these controversial results and propose future research challenges to develop new management strategies against these harmful PPN species.

1. Plant diversity can increase nitrogen cycling and decrease soil-borne pests, which are feedback mechanisms influencing subsequent plant growth. The relative strength of these mechanisms is unclear, as is the influence of preceding plant quantity and quality. Here, we studied how plant diversity in space and time influences subsequent crop growth. 2. During 2 years, we rotated two main crops (Avena sativa, Cichorium endivia) with four winter cover crop (WCC) species in monocultures and mixtures. We hypothesized that, relative to monocultures, WCC mixtures promote WCC biomass (quantity) and nitrogen concentration (quality), soil mineral nitrogen, soil organic matter, and reduce plant-feeding nematode abundance. Additionally, we predicted that preceding crops modified WCC legacies. By structural equation modelling (SEM), we tested the relative importance of WCC shoot biomass and nitrogen concentration on succeeding crop productivity directly and indirectly via nitrogen cycling and root-feeding nematode abundance. 3. WCC shoot biomass, soil properties and succeeding Avena productivity were affected by first-season cropping, whereas subsequent Cichorium only responded to the WCC treatments. WCC mixtures' productivity and nitrogen concentration showed over- and under-yielding, depending on mixture composition. Soil nitrogen and nematode abundance did not display WCC mixture effects. Soil organic matter was lower than expected after Raphanus sativus + Vicia sativa mixture. Subsequent Avena productivity depended upon mixture composition, whereas final Cichorium productivity was unresponsive to WCC mixtures. SEM indicated that WCC legacy effects on subsequent Avena (R² = 0.52) and Cichorium (R² = 0.59) productivity were driven by WCC biomass and nitrogen concentration, although not by the quantified soil properties. 4. Synthesis and applications. Through understanding plant-soil feedback, legacy effects of plant species and species mixtures can be employed for sustainable management of agro-ecosystems. Biomass and nitrogen concentration of plants returned to the soil stimulate subsequent plant productivity. Winter cover crop quantity and quality are both manipulable with mixtures. The specificity of spatial and temporal diversity effects warrants consideration of plant species choice in mixtures and rotations for optimal employment of beneficial legacy effects.

Plant-parasitic nematodes have been estimated to annually cause around US $173 billion in damage to plant crops worldwide. Moreover, with global climate change, it has been suggested that the damage to crops from nematodes is likely to increase in the future. Currently, a variety of potentially dangerous and toxic chemical agents are used to limit the damage to crops by plant-parasitic nematodes. As an alternative to chemicals and a more environmentally friendly means of decreasing nematode damage to plants, researchers have begun to examine the possible use of various soil bacteria, including plant growth-promoting bacteria (PGPB). Here, the current literature on some of the major mechanisms employed by these soil bacteria is examined. It is expected that within the next 5–10 years, as scientists continue to elaborate the mechanisms used by these bacteria, biocontrol soil bacteria will gradually replace the use of chemicals as nematicides.

Plant-parasitic nematodes (PPNs) are one of the most destructive plant pathogens worldwide, and controlling them is extremely challenging. Volatile organic compounds (VOCs), which naturally exist in plants and microorganisms, play an important role in the biological control of PPNs and are considered potential substances for the development of commercial nematicides. This paper summarizes the VOCs produced by microorganisms and plants as well as their toxic effects on PPNs. VOCs from 26 microbial strains and 51 plants that are active against nematodes from over the last decade were reviewed. Furthermore, the mechanisms of toxicity of some VOCs against PPNs are also illustrated.

Background Plant-parasitic nematodes (PPNs) that cause most damage include root-knot nematodes (RKNs) which are a major impediment to crop production. Root-knot nematodes, like other parasites, secrete proteins which are required for parasite proliferation and survival within the host during the infection process. Results Here, we used various computational tools to predict and identify classically and non-classically secreted proteins encoded in the Meloidogyne javanica genome. Furthermore, functional annotation analysis was performed using various integrated bioinformatic tools to determine the biological significance of the predicted secretome. In total, 7,458 proteins were identified as secreted ones. A large percentage of this secretome is comprised of small proteins of ≤ 300 aa sequence length. Functional analyses showed that M. javanica secretome comprises cell wall degrading enzymes for facilitating nematode invasion, and migration by disintegrating the complex plant cell wall components. In addition, peptidases and peptidase inhibitors are an important category of M. javanica secretome involved in compatible host-nematode interactions. Conclusion This study identifies the putative secretome encoded in the M. javanica genome. Future experimental validation analyses can greatly benefit from this global analysis of M. javanica secretome. Equally, our analyses will advance knowledge of the interaction between plants and nematodes.

Aims Root lesion nematodes (RLN) have negative impacts on legume-grass systems. These impacts might be moderated by bacterial feeding nematodes (BFN) presence. It remains unknown how these trophic groups of nematodes interactively impact plant productivity and dynamics of carbon (C) and nitrogen (N) in grass-legume mixtures. We addressed this research gap using inter-kingdom interactions in a model system. Methods Chickpea and oat were grown in mono- and mixed cultures, and RLN and BFN were applied alone and in combination. Plant biomass, shoot C and N content and isotopic composition, and mineral N in soil were measured. Results RLN presence reduced root biomass across treatments. This reduction was stronger in the grass than the legume and was not modified by BFN. Nematodes increased plant shoot N concentrations. RLN and BFN had interactive effects on shoot nutrient concentration resulting in reduced shoot C concentration when both trophic groups were combined. Shoot δ 15 N data revealed transfer of symbiotically fixed N from chickpea to oat in the presence of RLN. However, this N transfer did not result in improved oat growth. Conclusions Interactive effects of soil organisms can cascade aboveground, influencing C and N dynamics and ecosystem productivity.

Main conclusionExpression levels of AtPP2-A3 and AtPP2-A8 are reduced in syncytia induced by Heterodera schachtii and decline of their expression levels decreases host susceptibility, whereas their overexpression promotes susceptibility to parasite.Plant-parasitic nematodes cause huge crop losses worldwide. Heterodera schachtii is a sedentary cyst-forming nematode that induces a feeding site called a syncytium via the delivery of secreted chemical substances (effectors) to host cells, which modulate host genes expression and phytohormone regulation patterns. Genes encoding the Nictaba-related lectin domain have been found among the plant genes with downregulated expression during the development of syncytia induced by H. schachtii in Arabidopsis thaliana roots. To investigate the role of two selected Nictaba-related genes in the plant response to beet cyst nematode parasitism, mutants and plants overexpressing AtPP2-A3 or AtPP2-A8 were infected, and promoter activity and protein localization were analyzed. In wild-type plants, AtPP2-A3 and AtPP2-A8 were expressed only in roots, especially in the cortex and rhizodermis. After nematode infection, their expression was switched off in regions surrounding a developing syncytium. Astonishingly, plants overexpressing AtPP2-A3 or AtPP2-A8 were more susceptible to nematode infection than wild-type plants, whereas mutants were less susceptible. Based on these results and changes in AtPP2-A3 and AtPP2-A8 expression patterns after treatments with different stress phytohormones, we postulate that the AtPP2-A3 and AtPP2-A8 genes play important roles in the defense response to beet cyst nematode infection.