Isolation and characterisation of virulent bacteriophage targeting canola rhizosphere bacteria Klebsiella grimontii and Bacillus sp.

Bats as pest-fighting pioneers: Seasonal contributions in South China’s mountainous agroecosystem

Plant-positive single-stranded RNA viruses induce vesicles that are crucial for viral infection, replication and spread. However, the mechanisms underlying the vesicle biogenesis induced by negative single-stranded RNA viruses remain largely unknown. Here, a negative single-stranded RNA virus, tomato spotted wilt orthotospovirus (TSWV) which is a representative member of genus Orthotospovirus in the Tospoviridae family, was used as a model to investigate the mechanisms involving the interaction between the viral and the host plant proteins in vesicle formation and function. We found that the nonstructural protein (NSm) of TSWV, could induce endoplasmic reticulum (ER)-derived pathological vesicle biogenesis. In addition, NSm might hijack the host immunity proteins, NtPOX1 (a peroxidase) and pathogenesis-related protein NtPR-4A, to form a potential tetrameric protein complex with Sar1 (a small GTPase), which was crucial for NSm-induced vesicle biogenesis. The results also showed that these ER-derived pathological vesicles provided sites for TSWV replication. These findings provide novel and robust insights for understanding the infection processes and mechanisms of plant-negative single-stranded RNA viruses.

Phyllosphere epiphytic fungi: Diversity, environmental interactions, and selection factors

Seven commercially available seed-applied nematicides were evaluated in a greenhouse pot experiment and in two field experiments using Meloidogyne incognita-susceptible and partially resistant maturity group IV soybean cultivars. Nematicide treatments were abamectin, fluopyram, pydiflumetofen, Bacillus amyloliquefaciens (PTA4838), B. amyloliquefaciens + cis-jasmone, B. flavus (I-1582), and Burkholderia rinojensis (A396). Soybean plants were inoculated with approximately 3,000 M. incognita eggs/pot in the greenhouse experiment. Field experiments were conducted in sites with naturally high infestation levels, averaging 450 nematodes/100 cm3 soil after harvest. In the greenhouse, lower root galling and nematode reproduction were observed with seed-applied fluopyram compared to other nematicides and the non-treated control on a susceptible soybean cultivar. Whereas none of the seed-applied nematicides consistently suppressed root galling or protected grain yield in either the susceptible or partially resistant soybean cultivars in the field experiments. Nematicides provided an average of 0.3% yield protection for susceptible cultivars and had no measurable effect on partially resistant cultivars. In contrast, partially resistant cultivars produced, on average, 50% greater grain yield than the susceptible cultivar. These results demonstrate that seed-applied nematicides provide minimal yield protection under high M. incognita population densities, whereas host plant resistance remains the most effective and reliable management strategy in soybean production.

Ceratocystis paradoxa, a filamentous ascomycete and soil-borne wound pathogen, attacks various host plants such as Ananas comosus, Cocos nucifera and Saccharum officinarum.Secretory proteins are critical for phytopathogenic infection, yet related studies on C. paradoxa remain scarce. Using WoLF PSORT, TMHMM, and big-PI Predictor, we predicted the secretory proteins in C. paradoxa. Carbohydrate-active enzymes and pathogenicity-related proteins were predicted by HMMER and PHI-base. Effectors were predicted by EffectorP v3.0. RT-qPCR was used to screen effectors highly expressed during early infection. In this study, 253 secretory proteins were predicted from its 6,931 annotated genomic proteins. These proteins vary from 61 to 1894 residues in length, with signal peptides ranging from 13 to 35 residues in length. 58.89% of the signal peptide cleavage sites follow the canonical "Ala-X-Ala" motif, a substrate recognized by signal peptidase I. UsingHMMER software, 78 carbohydrate-active enzymes (CAZymes) were predicted, including 45 glycoside hydrolases, 24 auxiliary activities, 4 polysaccharide lyases, 3 carbohydrate esterases, 1 glycosyl transferase and 1 carbohydrate binding module. Additionally, 144 secretory proteins matched known entries in thePHI-base, suggesting potential roles in pathogenicity. We further predicted56 candidate effectors, classified into9 cytoplasmic and 47 apoplastic types.Notably,six effector proteinswere highly expressed during early infection, and three of them were predicted to be CAZymes. This study systematically predicted 253 potential secretory proteins from C. paradoxa via multi-tool prediction, which may provide a comprehensive inventory of its pathogenicity-related secretome. These proteins potentially include 78 carbohydrate-active enzymes, 144 pathogenicity-related proteins, and 56 candidate effectors. Notably, six effectors highly expressed during early infection-three of which may have carbohydrate-active enzyme activity-could be key candidates involved in initial infection. Our findings may fill the gap in C. paradoxa secretory protein research, lay a potential foundation for elucidating its pathogenic mechanisms, and provide potential targets for controlling this soil-borne pathogen.

Tea (Camellia sinensis) is a globally significant economic crop, and its desirable quality and health benefits are largely credited to catechin derivatives. Plant growth-promoting rhizobacteria (PGPR), such as Bacillus velezensis, are well-known for enhancing the environmental fitness and disease resistance of plants. However, the regulation of their impact on tea catechin biosynthesis remains unclear. While previous studies have focused on PGPR-facilitated growth promotion in crops like tomatoes and rice, the physiological mechanisms by which microbes regulate secondary metabolism in tea-especially under co-inoculation conditions-remain largely underexplored. This study examined the effects of B. velezensis SD24, isolated from tea rhizosphere soil, on catechin derivative accumulation of tea leaves by altering gene expression and the rhizosphere microbiome. Strain SD24 exhibited broad-spectrum antimicrobial activity against various pathogens due to behaving antimicrobial gene clusters. Tea plants inoculated with SD24 showed significantly increased levels of catechin derivatives in their leaves. This was likely achieved by upregulation of leucoanthocyanidin reductase and anthocyanidin reductase within the phenylpropanoid pathway. Additionally, chlorophyll content was increased. Transcriptomic analysis revealed a notable enrichment in biosynthesis of secondary natural products among the tea genes activated by SD24 inoculation. Metagenomic analysis further demonstrated that SD24 inoculation led to a restructuring of the tea rhizosphere microbiome. Notably, co-inoculation with Piriformospora indica, a beneficial endophytic fungus, suppressed SD24-induced gene expression and catechin accumulation, underscoring its antagonism toward SD24. These findings suggest that B. velezensis SD24 enhances tea quality, probably by transcriptionally activating the synthesis of catechin derivatives, a process associated with the restructuring of the rhizosphere microbiome.IMPORTANCEThe mechanisms through which plant growth-promoting rhizobacteria (PGPR) influence secondary metabolism in perennial crops remain poorly understood. This study demonstrates that Bacillus velezensis SD24, a tea rhizosphere isolate, significantly enhances the accumulation of health-beneficial catechin derivatives in tea leaves. This quality improvement is associated with transcriptionally upregulating key biosynthetic genes (LAR and ANR) and concurrently restructuring the rhizosphere microbiome. Furthermore, we reveal a critical antagonistic interaction, where the beneficial fungus Piriformospora indica suppresses these SD24-induced effects. Our findings provide crucial insights into how specific PGPR strains may directly enhance tea quality by affecting host plant metabolism and the root microbiome, highlighting the complex and tailored microbial interactions that could be harnessed for sustainable agriculture.

Citrus huanglongbing (HLB) is recognized as the most destructive bacterial disease affecting citrus. Among the causal agents, Candidatus Liberibacter asiaticus (Las) is the predominant species causing HLB epidemics worldwide. Detecting this phloem limited bacterium at early or low titer stages and assessing its cellular activity remain major challenges for HLB research and management. To address these limitations, we developed a one step reverse transcription quantitative PCR (RT qPCR) assay for highly sensitive Las detection using total nucleic acids and the established Li 16S rRNA/rDNA primer-probe set. This method simultaneously amplifies both Las 16S rRNA and rDNA in a single reaction, increasing sensitivity by up to 500 fold compared with qPCR, which targets only 16S rDNA. The improved sensitivity reduced false negatives, expanded sampling capacity, and enabled detection of low titer infections previously undetectable. In addition, the higher abundance of 16S rRNA generated a consistent Ct gap between RT qPCR and qPCR, which we used to estimate relative Las cell activity in vivo in host insects and plants and to identify the most effective inoculum sources. This comparative detection strategy was further applied to evaluate inoculum potential, monitor changes in relative cell activity during in vitro cultures, and assess antimicrobial treatments targeting Las. The persistent detection of long lasting, low titer Las infections underscores the complex biology of the HLB causal agent and highlights ongoing challenges for effective disease management.

Aphis gossypii shows strong intraspecific host specialization, making it an excellent model for olfaction-driven host adaptation. Hap1 (cotton-specialized haplotype) and Hap3 (cucurbit-specialized haplotype) are the two main haplotypes. Odorant-binding proteins (OBPs) play pivotal roles in insect host recognition and are potential RNAi targets. This study aims to elucidate the functional role of AgosOBP3 in host specialization of A. gossypii. We used genome-wide identification, transcriptomic comparison, RNA interference, host choice assays and life table analysis to characterize AgosOBP3 function. We identified 13 OBP genes from the A. gossypii genome, among which AgosOBP3 expression in polyphagous Hap4 was significantly higher than in the cotton-specialized Hap1 (1.79-fold, P < 0.05). Life table assays confirmed that Hap1 performed well on cotton but exhibited extremely low survival and reproduction on cucumber, demonstrating typical host-specialization characteristics. RNAi-mediated silencing of AgosOBP3 (46.8% expression reduction) substantially altered host preference in Hap1: at 48 h, 70% of control aphids selected cotton, whereas 65% of treated aphids chose cucumber, representing a significant reversal in host selection. Bioassay results revealed that RNAi-treated Hap1 A. gossypii showed a 39.6% increase in fecundity on cucumber but a 39.5% decrease on cotton. The expression level of AgosOBP3 directly governs host preference in A. gossypii toward its specialized hosts. Interference with this gene disrupts host selection preference, redirecting the cotton-specialized haplotype toward nonadapted hosts. Our results establish AgosOBP3 as a critical determinant of host specialization, offering theoretical insights and a viable molecular target for olfactory disruption-based sustainable management strategies against aphid pests. © 2026 Society of Chemical Industry.

The antioxidant defence system is crucial for herbivorous insects to adapt to various host plants. This study focused on catalase 2 gene (HcCAT2) to investigate the antioxidant mechanisms that underlie the ability of Hyphantria cunea to adapt to a wide range of hosts and to develop a disruptor for its polyphagous behaviour. Results indicated that, compared to larvae fed on the highly preferred host plant Morus alba, HcCAT2 expression increased 33.19- to 47.25-fold in larvae reared on Betula platyphylla and Tilia amurensis with moderate and low preference, respectively. Silencing HcCAT2 consistently reduced larval body weight and downregulated growth-related genes (e.g., Cyclin A2 and Decapentaplegic) across all host plant groups. Moreover, HcCAT2 silencing significantly downregulated key glycolytic genes (Hexokinase and Pyruvate kinase), the tricarboxylic acid cycle gene (Isocitrate Dehydrogenase 2) and lipid metabolism genes (e.g., Acetyl-CoA Carboxylase) in larvae fed on all three host plants. The redox response in larvae was complex, as HcCAT2 silencing led to a marked downregulation of negative regulators of oxidative damage and key ROS-producing genes. The nucleic acid pesticide CS-dsHcCAT2, designed to target HcCAT2 expression, demonstrated potent silencing efficacy. Treatment with CS-dsHcCAT2 suppressed larval body weight on all host plants. Collectively, the HcCAT2-mediated antioxidant defence system is critical to the host plant adaptation of H. cunea, and CS-dsHcCAT2, by inhibiting HcCAT2 expression, holds promise as an effective agent to disrupt the polyphagous behaviour of H. cunea.

Early mutualistic interactions between host plants and their rhizosphere microbes have the potential to provide soil-borne disease resistance. However, it remains unclear how the early rhizosphere microbiome protects against viral diseases such as wheat yellow mosaic virus, which is a major threat to global wheat production. We combined field trials with microbiome transplantation experiments to investigate the role of early rhizosphere microbiomes in suppressing wheat yellow mosaic disease. To uncover the underlying mechanisms, we further performed integrated multi-omics analyses of microbial communities, functional genes, and metabolic profiles. Disease-resistant wheat cultivars were consistently associated with distinct seedling rhizosphere microbiome assembly, including a lower Polymyxa graminis abundance, lower community compositional variation, and enrichment of beneficial taxa such as Bacillus, Pseudomonas, and Trichoderma. Resistant cultivars also exhibited distinct rhizosphere metabolite profiles, including higher levels of glyceraldehyde and N-acetyltryptophan, which were positively associated with keystone microbial taxa and stimulated representative isolates invitro. Isolate-based and synthetic community validation further supported the functional relevance of these taxa, while microbial inoculation was associated with reduced vector abundance, lower virus accumulation, and activation of host defense-related pathways. Our findings showed that early cultivar-dependent rhizosphere microbiome assembly was closely linked to resistance against soil-borne viral disease in wheat.

The phyllosphere microbiome plays crucial roles in plant health, but evidence of 'cry for help' strategy in the face of pathogen attack in the phyllosphere remains limited, particularly for the microbiomes of distinct leaf ecological niches. We investigated whether foliar pathogen anthracnose (Colletotrichum lentis) influenced the assembly and functions of microbiomes in epiphytic and endophytic niches of the phyllosphere of common vetch (Vicia sativa) leaves. We also evaluated synthetic microbial communities (SynComs), including representatives of disease-associated strains, for pathogen protection. Anthracnose mediated the deterministic assembly process of epiphytic bacterial and endophytic fungal communities, and increased the complexity of bacterial co-occurrence networks. Iron competition and antifungal genes were also enriched in the epiphytic bacteria, which produce siderophores and degrade fungal cell walls to counteract pathogens. SynComs of beneficial epiphytic bacteria partially protect hosts by regulating bacterial interactions and inducing host immune responses. These findings suggest that disease drives the deterministic assembly of distinct phyllosphere microbiomes, their diversity and their function. Moreover, SynComs from the epiphytic niche can confer host plant disease resistance.

Planthoppers transmit pathogens to various economically important crops. In Central Europe, the sugar beet, Beta vulgaris L. ssp. vulgaris var. altissima (Döll) (Amaranthaceae: Caryophyllales) and potato production are threatened by diseases associated with the γ-proteobacterium "Candidatus Arsenophonus phytopathogenicus" and the phytoplasma "Candidatus Phytoplasma solani". Infections cause yellowing and wilting, reduce sugar yield in sugar beet, induce rubbery taproots in potato, and can lead to plant decline. In Austria, the cixiid Reptalus quinquecostatus (Dufour) is considered a main vector of these pathogens. While several plant species have been reported as feeding or shelter plants for adult R. quinquecostatus, no reproductive host plant supporting nymphal development has previously been confirmed. In this study, we investigated whether sugar beet is a potential host plant for the development of R. quinquecostatus. Host plant trials were conducted using potted sugar beet plants placed outdoors in insect cages. Four cages were infested with a total of 15 adult Reptalus spp. (10 females and 5 males) per cage to allow oviposition. Egg masses and nymphs were observed in 75% of the cages during the trial period. After 366 ± 3.46 (SD) d, 4 adult R. quinquecostatus emerged from 2 out of 4 cages. Our findings provide the first experimental evidence that sugar beet can function as a reproductive host plant for R. quinquecostatus.

Most terrestrial plants can establish symbiotic relationships with arbuscular mycorrhizal (AM) fungi, which increase the host plants’ resilience to pathogens. The effect of pre-inoculation with AM fungi as a bio-agent on lettuce (Lactuca sativa L.) plant resistance against Alternaria alternata RaSh3 leaf spot disease was investigated. The findings demonstrated that in A. alternata-infected plants, AM fungi could effectively colonize lettuce roots at a higher rate (100%) than in non-infected plants (91.66%). According to the disease assessment, lettuce plants pre-inoculated with AM and infected with A. alternata RaSh3 showed a 33.33 and 30.00% reduction in disease incidence and severity, respectively. During A. alternata RaSh3 infection, the primary growth responses, pigment fraction, proline, and carbohydrates of lettuce plants were reduced, accompanied by increases in oxidative stress markers [malondialdehyde (87%) and hydrogen peroxide (30.8%)]. Contrarily, AM-inoculated plants showed a significant increase in growth, photosynthetic pigments, osmolytes and enzymatic and non-enzymatic antioxidant enzymes either in A. alternata RaSh3-infected or non-infected ones. Overall, our results highlight the significance of AM fungi in alleviating infection symptoms by increasing proline (13%), flavonoids (28.3%), and phenolic compounds (44.7%). Moreover, a boost in the enzymatic status (phosphatases, antioxidants, and phenylalanine ammonia-lyase) was detected in A. alternata RaSh3-infected plants due to AM inoculation, proving the essential role of its inoculation in increasing plant resistance against A. alternata RaSh3. Finally, this experiment has proved the sustainable defense strategy of mycorrhizal symbiosis as a new bio-agent for the biological control of A. alternata in lettuce plants.

ABSTRACT Pathogen effectors mediate infection and pathogenesis, and extensive research has been conducted on this topic. In contrast, studies on endophyte effectors remain limited, and their functions and mechanisms of action are still not well understood. Here, we report a novel effector identified from the endophytic Fusarium lateritium. Knockout of this effector reduced the colonization rate of the endophyte in the host plant by approximately 70%; therefore, we named it Colonization-Related Effector Protein 1 (CREP1). We found that CREP1 strongly activates host plant immunity and induces cell necrosis in Nicotiana benthamiana leaves. Disruption of CREP1 resulted in significant downregulation of immune defense-related genes in the host plant, accompanied by an approximately 50% decrease in the plant growth-promoting ability of the endophytic fungus. Further investigation revealed that CREP1 interacts with the plant cell-surface recognition receptor protein NbEIX2 to regulate plant immunity. These findings demonstrate that CREP1 is a necrosis-inducing effector in F. lateritium that modulates plant immunity through its interaction with NbEIX2, affecting the colonization and growth-promoting capacity of the endophytic fungus in plants.

Arbuscular mycorrhizal (AM) fungi change phosphorus (P) uptake and plant growth. The degree of change is defined as mycorrhizal dependency. Mycorrhizal dependency differs among cultivars and among different levels of soil P availability. The purpose of this study was to study the effect of AM fungus colonization on Allium fistulosum (A. fistulosum) with different mycorrhizal dependency grown at different levels of soil P availability. Twenty cultivars of A. fistulosum were grown with or without (control) AM fungus Rhizophagus spp. strain R-10 for 82 days. Three cultivars of A. fistulosum with different mycorrhizal dependency were inoculated and grown in soils fertilized at the rate of 0.43, 0.87, 2.18, and 4.36g P kg-1 soil (P1, P2, P3, and P4, respectively) with or without (control) the AM fungus for 82 days. AM colonization, root length, shoot dry weight, and P concentration were determined. AM colonization increased shoot P content and shoot dry weight. Mycorrhizal dependencies were different among 20 cultivars and Mogamigawa, Shonan, and Kannonhosonegi were used as high, middle and low mycorrhizal dependency cultivars, respectively. Shoot P content of Mogamigawa and Shonan cultivars was higher in the inoculated plants than that in the uninoculated plants at P1, P2 and P3 soil fertilization rates. Shoot P content of the Kannonhoso was higher in the inoculated plants than that in the uninoculated plants at P1. Shoot dry weight of the Mogamigawa and Shonan was higher in the inoculated plant than that in the uninoculated plant at P1. These results suggest that selection of an appropriate cultivar and soil P availability are important factors in determining possible mutualistic, commensalistic, and parasitic relationships between the AM fungus and the host plant.

Emerging pandemics are often driven by viral spillover events. However, predicting them remains difficult due to the complex interplay between viral genetics, host adaptability, and ecological dynamics. While traditional models rely on ecological or host traits, recent advances using viral sequence data and machine learning approaches have improved prediction accuracy. However, these approaches often lack a unified framework applicable across diverse viral families and host kingdoms, and are further constrained by the limited availability of comprehensive datasets. Here, we introduce SPHAK, a simple protein-based sequence similarity framework that could quantify spillover risk and predict viral family. By focusing on proteins, SPHAK is found to be a more effective way for identifying key amino acid patterns that can distinguish viral hosts. Since proteins are directly involved in infection, they could serve as a more informative probe than genome sequences. SPHAK is both accurate and generalizable, enabling its application across diverse viral families in animal and plant hosts. Application to influenza virus sequences validates the framework's effectiveness, with SPHAK successfully distinguishing spillover-associated protein signatures across multiple pandemic-relevant subtypes, including H1N1, H3N2, and H5N1. The predictive capacity of SPHAK supports its use in early warning systems and targeted surveillance, offering a practical tool to enhance pandemic preparedness and response.

Phenotypic plasticity in insect wing dimorphism mediates a key trade-off between dispersal and reproduction, but how host plant nutritional cues are transduced into discrete developmental outcomes remains unclear. We investigated the role of glucose in the regulation of wing morph fate in the small brown planthopper (SBPH, Laodelphax striatellus), and the underlying mechanisms were also explored. Elevating glucose via root supplementation or direct injection promotes long-winged (LW) morphs, whereas blocking sugar hydrolysis (via Validamycin A) or glucose availability (via RNAi) induces short-winged (SW) morphs, confirming glucose as the proximate nutritional cue. Mechanistically, glucose signals through the conserved energy sensor AMP-activated protein kinase (AMPK). Low glucose activates AMPK, which directly interacts with the transcription factor Forkhead box O (FoxO) to drive its nuclear translocation. Nuclear FoxO represses expression of the wing master regulator vestigial (Vg), triggering SW development. Conversely, high glucose suppresses AMPK activity, sequesters FoxO in the cytoplasm, and derepresses Vg to induce LW morphs. The glucose-AMPK-FoxO-Vg signaling axis regulates wing dimorphism in SBPH in response to host-derived sugar. The data reveals a previously unrecognized role of AMPK in insect phenotypic plasticity and provides a mechanistic framework linking environmental nutrition to adaptive life-history strategies. © 2026 Society of Chemical Industry.

Many tropical butterflies exhibit seasonal wing pattern plasticity, producing cryptic dry-season morphs with small or no ventral eyespots and conspicuous wet-season morphs with large wing-marginal eyespots that deflect predator attacks away from vital body parts. Eyespot size is influenced by temperature during larval development. However, many tropical regions lack a predictable temperature-rainfall correlation, limiting temperature's reliability as a cue. Relative humidity (humidity), which increases with wet season's approach, presents a potential environmental cue. We tested whether humidity modulates eyespot-size plasticity in two sympatric butterflies experiencing similar ecological pressures. High humidity directly induced larger eyespots in Mycalesis mineus, compared with those from low humidity. In contrast, Melanitis leda showed no direct effect; instead, humidity modulated eyespot size indirectly through induced changes in host plant quality. Since the late larval and prepupal stages are temporally closer to the adult environment, selection may favour greater sensitivity during these stages. Using a humidity switching experiment at different developmental stages, we demonstrated that, in M. mineus, wandering larval and prepupal stages are sensitive to humidity, while M. leda remained insensitive. This study highlights how two diverging species, evolving under similar ecological pressures, integrate environmental cues in distinct ways to modulate wing pattern plasticity.

Hostplant availability is a key factor influencing butterfly distribution, particularly in urban environments with limited ecological resources. This study aimed to examine the colonization, oviposition behavior, and pre-adult development of Pachliopta antiphus antiphus following the introduction of its host plant Aristolochia tagala in a residential area in Palembang, Indonesia. A direct observation method was applied to monitor butterfly presence, egg-laying activity, and development from egg to adult stage. All observed individuals (total of 12 eggs successfully developed into adults. Eggs were laid singly, primarily on young leaves. Larval development consisted of four instars, with increasing body size and feeding rate at each stage. The duration from egg to adult emergence fell within the normal developmental range reported for the genus. This finding highlights the importance of hostplant presence in supporting butterfly persistence and suggests a nested pattern of species occurrence within urban landscapes.