Search Results (589)

Wheat (Triticum aestivum L.) is a crucial global food crop. The intensive crop farming, monoculture cultivation, and impact of climate change affect the susceptibility of wheat cultivars to biotic stresses, mainly caused by soil fungal pathogens, especially those belonging to the genus Fusarium. This situation threatens yield and grain quality through root and crown rot. While conventional chemical fungicides face resistance issues and environmental concerns, biological alternatives like seed priming with natural metabolites are gaining attention. Polyamines, including putrescine, spermidine, and spermine, are attractive priming agents influencing plant development and abiotic stress responses. Spermine in particular shows potential for in vitro antifungal activity against Fusarium. Optimising spermine concentration for seed priming is crucial to maximising protection against Fusarium infection while ensuring robust plant growth. In this research, we explored the potential of the polyamine spermine as a seed treatment to enhance wheat resilience, aiming to identify a sustainable alternative to synthetic fungicides. Our findings revealed that a six-hour seed soak in spermine solutions ranging from 0.5 to 5 mM did not delay germination or seedling growth. In fact, the 5 mM concentration significantly stimulated root weight and length. In complementary in vitro assays, we evaluated the antifungal activity of spermine (0.5–5 mM) against three Fusarium species. The results demonstrated complete inhibition of Fusarium culmorum growth at 5 mM spermine. A less significant effect on Fusarium graminearum and little to no impact on Fusarium oxysporum were found. The performed analysis revealed that the spermine had a fungistatic effect against the pathogen, retarding the mycelium growth of F. culmorum inoculated on the seed surface. A pot experiment with Bulgarian soft wheat cv. Sadovo-1 was carried out to estimate the effect of seed priming with spermine against infection with isolates of pathogenic fungus F. culmorum on plant growth and disease severity. Our results demonstrated that spermine resulted in a reduced distribution of F. culmorum and improved plant performance, as evidenced by the higher fresh weight and height of plants pre-treated with spermine. This research describes the efficacy of spermine seed priming as a novel strategy for managing Fusarium root and crown rot in wheat. Full article

In chili cultivation, obstacles to continuous cropping significantly compromise crop yield and soil health, whereas crop rotation can enhance the microbial environment of the soil and reduce disease incidence. However, its effects on the diversity of rhizosphere soil microbial communities are not clear. In this study, we analyzed the composition and characteristics of rhizosphere soil microbial communities under chili continuous cropping (CC) and chili–cotton crop rotation (CR) using high-throughput sequencing technology. CR treatment reduced the alpha diversity indices (including Chao1, Observed_species, and Shannon index) of bacterial communities and had less of an effect on fungal community diversity. Principal component analysis (PCA) revealed distinct compositional differences in bacterial and fungal communities between the treatments. Compared with CC, CR treatment has altered the structure of the soil microbial community. In terms of bacterial communities, the relative abundance of Firmicutes increased from 12.89% to 17.97%, while the Proteobacteria increased by 6.8%. At the genus level, CR treatment significantly enriched beneficial genera such as RB41 (8.19%), Lactobacillus (4.56%), and Bacillus (1.50%) (p < 0.05). In contrast, the relative abundances of Alternaria and Fusarium in the fungal community decreased by 6.62% and 5.34%, respectively (p < 0.05). Venn diagrams and linear discriminant effect size analysis (LEfSe) further indicated that CR facilitated the enrichment of beneficial bacteria, such as Bacillus, whereas CC favored enrichment of pathogens, such as Firmicutes. Fusarium solani MG6 and F. oxysporum LG2 are the primary chili root-rot pathogens. Optimal growth occurs at 25 °C, pH 6: after 5 days, MG6 colonies reach 6.42 ± 0.04 cm, and LG2 5.33 ± 0.02 cm, peaking in sporulation (p < 0.05). In addition, there are significant differences in the utilization spectra of carbon and nitrogen sources between the two strains of fungi, suggesting their different ecological adaptability. Integrated analyses revealed that CR enhanced soil health and reduced the root rot incidence by optimizing the structure of soil microbial communities, increasing the proportion of beneficial bacteria, and suppressing pathogens, providing a scientific basis for microbial-based soil management strategies in chili cultivation. Full article

The soil-borne fungal pathogen Verticillium dahliae causes devastating vascular wilt disease in numerous crops, including cotton. In this study, we reveal that VdSOX1, a highly conserved sarcosine oxidase gene, is significantly upregulated during host infection and plays a multifaceted role in fungal physiology and pathogenicity. Functional deletion of VdSOX1 leads to increased fungal virulence, accompanied by enhanced microsclerotia formation, elevated carbon source utilization, and pronounced upregulation of effector genes, including over 50 predicted secreted proteins genes. Moreover, the VdSOX1 knockout strains suppress the expression of key defense-related transcription factors in cotton, such as WRKY, MYB, AP2/ERF, and GRAS families, thereby impairing host immune responses. Transcriptomic analyses confirm that VdSOX1 orchestrates a broad metabolic reprogramming that links nutrient acquisition to immune evasion. Our findings identify VdSOX1 as a central regulator that promotes V. dahliae virulence by upregulating effector gene expression and suppressing host immune responses, offering novel insights into the molecular basis of host–pathogen interactions and highlighting potential targets for disease management. Full article

Road density is a key indicator of human activity, causing habitat loss and fragmentation. Soil fungi, essential for ecosystem functioning, are sensitive bioindicators. Yet their responses to road density in urban green spaces are poorly characterized. Here, we analyzed the composition of the dominant fungal community, examined both the direct and indirect effects of road density on soil fungal communities, and identified specialist species. Focusing on Shanghai, China, a rapidly urbanizing city, we considered both edaphic factor and the road network. Through machine learning and Spearman correlation regression analyses, we quantified the relative importance of road density and edaphic factor in shaping fungal community composition and employed occupancy-specificity modeling to identify specialist taxa. Our results revealed that Ascomycota, Basidiomycota, Zygomycota, Rozellomycota, Chytridiomycota, and Glomeromycota were the dominant phyla, accounting for 93% of the retrieved ITS sequences. Road density was found to be the primary driver of fungal community composition, followed by soil lead and potassium concentrations. Notably, opportunistic pathogens (Acremonium spp.) correlated positively with road density (p < 0.001). Specialist species in high-density areas were primarily pathotrophic fungi, while saprotrophic fungi dominated in low-density areas. These findings highlight the need for urban planning strategies to mitigate the ecological impact of road density. Full article

Almond decline and dieback have become significant challenges in newly established orchards, with symptoms including internal necrosis, canker, and external gummosis. This work aims to explore the potential fungal and bacterial causative agents through metabarcoding and traditional culture plate isolation across six almond cultivars. Our results emphasize the multifactorial nature of almond decline and dieback, with possible co-infections by opportunistic fungi and bacteria playing a central role. Classical isolation identified 47 fungal species or genera, including Diaporthe amygdali, Diplodia corticola, Phytophthora sp., and several Fusarium species. Almond metabarcoding revealed a more diverse microbial community, highlighting the prevalence of soilborne pathogens such as Neocosmospora rubicola, Dactylonectria estremocensis, and Plectosphaerella niemeijerarum. Soil metabarcoding suggested that these pathogens likely originate from nursery substrates or soils shared with other crops, such as olives and vineyards, that serve as a source of inoculum. ‘Soleta’ generally presented lower richness when compared to the other tested cultivars, suggesting a higher degree of biotic stress and decreased plant resilience. This study highlights the value of integrating NGS approaches to comprehensively study complex diseases and the need for further research on pathogen interactions and cultivar susceptibility for the future development of new sustainable, targeted management strategies in almond orchards. Full article

Plant microbiomes are vital for the growth and health of their host. Tree-associated microbiomes are shaped by multiple factors, of which the host is one of the key determinants. Whether different host genotypes affect the structure and diversity of the tissue-associated microbiome and how specific taxa enriched in different tree tissues are not yet well illustrated. Chinese fir (Cunninghamia lanceolata) is an important tree species for both economy and ecosystem in the subtropical regions of Asia. In this study, we investigated the tissue-specific fungal community structure and diversity of nine different Chinese fir genotypes (39 years) grown in the same field. With non-metric multidimensional scaling (NMDS) analysis, we revealed the divergence of the fungal community from rhizosphere soil (RS), fine roots (FRs), and thick roots (TRs). Through analysis with α-diversity metrics (Chao1, Shannon, Pielou, ACE, Good‘s coverage, PD-tree, Simpson, Sob), we confirmed the significant difference of the fungal community in RS, FR, and TR samples. Yet, the overall fungal community difference was not observed among nine genotypes for the same tissues (RS, FR, TR). The most abundant fungal genera were Russula in RS, Scytinostroma in FR, and Subulicystidium in TR. Functional prediction with FUNGuild analysis suggested that ectomycorrhizal fungi were commonly enriched in rhizosphere soil, while saprotroph–parasite and potentially pathogenic fungi were more abundant in root samples. Specifically, genotype N104 holds less ectomycorrhizal and pathogenic fungi in all tissues (RS, FR, TR) compared to other genotypes. Additionally, significant correlations of several endophytic fungal taxa (Scytinostroma, Neonothopanus, Lachnum) with the growth traits (tree height, diameter, stand volume) were observed. This addresses that the interaction between tree roots and the fungal community is a reflection of tree growth, supporting the “trade-off” hypothesis between growth and defense in forest trees. In summary, we revealed tissue-specific, as well as host genotype-specific and genotype-common characters of the structure and functions of their fungal communities. Full article

Reductive soil disinfestation (RSD) significantly alters soil characteristics, yet its combined effects with bacterial inoculation on subsequent rhizospheric microbial community composition remains poorly understood. To address this knowledge gap, we investigated the effects of RSD and endophytic Brevibacillus laterosporus inoculation on the composition, network, and predicted function of peanut rhizospheric bacteria and fungi. Our results demonstrated that RSD and B. laterosporus inoculation substantially increased rhizospheric bacterial diversity while reducing fungal diversity. Specifically, B. laterosporus-enhanced RSD significantly reshaped the bacterial community, resulting in increased relative abundances of Chloroflexi, Desulfobacterota, and Myxococcota while decreasing those of Firmicutes, Gemmatimonadota, and Acidobacteriota. The fungal community exhibited a more consistent response to RSD and B. laterosporus amendment, with reduced proportions of Ascomycota and Gemmatimonadota but an increase in Chytridiomycota. Network analysis revealed that B. laterosporus inoculation and RSD enhanced the bacterial species complexity and keystone taxa. Furthermore, canonical correspondence analysis indicated strong associations between the soil bacterial community and soil properties, including Eh, EC, NO₃⁻-N, and SOC. Our findings highlight that the shifts in bacterial taxa induced by B. laterosporus inoculation and RSD, particularly the keystone taxa identified in the network, may contribute to the suppression of soil-borne pathogens. Overall, this study provides a novel insight into the shifts in rhizospheric bacterial and fungal communities and their ecological functions after bacteria inoculation and RSD treatment. Full article

Intercropping has been widely proven to boost agricultural yields and control diseases. This study examined the impact of sugarcane monoculture (SM) and sugarcane–pumpkin intercropping (IP) systems on soil physicochemical characteristics and microbial community dynamics. Compared to monoculture, intercropping significantly increased soil pH by 8.82% and total potassium (TK) by 17.92%, while reducing soil organic matter (SOM) by 25.56%. Bacterial communities under intercropping exhibited significantly higher alpha and beta diversity, whereas fungal community diversity remained unaffected. Notably, the relative abundances of certain taxa with known roles in plant growth promotion and pathogen suppression—such as Anaeromyxobacter, Nitrospira, and Massilia—were enriched. Canonical correlation analysis revealed that bacterial community composition was strongly associated with TK, while fungal community structure correlated with variations in soil available nitrogen (AN). These findings indicate that sugarcane–pumpkin intercropping reshapes soil microbial communities and contributes to some improvement in soil nutrient availability. Full article

Seedlings of the ecologically important, critically endangered tree Ocotea monteverdensisis experience high mortality in the Monteverde, Costa Rica, cloud forests at the onset of the wet season, yet there are no studies suggesting the disease etiology. Here, healthy and diseased plant root and bulk soils were analyzed for various carbon and nitrogen (N) metrics and respiration levels, and DNA sequence-based bacterial and fungal community compositions. All nitrogen metric levels were greater in diseased vs. healthy plant root soils, which could enhance pathogen growth and pathogenic mechanisms. Greater DNA percentages from several potential pathogens were found in diseased vs. healthy plant root soils, suggesting this disease may be associated with a root pathogen. The DNA of the fungus Mycosphaerella was at greater levels in diseased vs. healthy plant root soils than other potential pathogens. Mycosphaerella causes similar diseases in other plants, including coffee, after onset of the wet season. The O. monteverdensis disease also occurs in seedlings planted within or near former coffee plantations at wet season onset. Distance-based linear model analyses indicated that NO₃⁻ levels best predicted the pattern of fungal pathogens in the soils, and Mycosphaerella and Tremella best predicted the patterns of the different N metrics in the soils, supporting their possible roles in this disease. Full article

The long-term monocropping of red kidney beans in agricultural fields can lead to the occurrence of soil-borne diseases. Alterations in the composition of the soil microbial community are a primary cause of soil-borne diseases and a key factor in continuous cropping obstacles. Research exploring how different cultivation modes can modify the diversity and composition of the rhizosphere microbial community in red kidney beans, and thus mitigate the effects of continuous cropping obstacles, is ongoing. This study employed three cultivation modes: the continuous monocropping of red kidney beans, continuous monocropping of soybeans, and red kidney bean–soybean intercropping. To elucidate the composition and diversity of rhizosphere microbial communities, we conducted amplicon sequencing targeting the V3-V4 hypervariable regions of the bacterial 16S rRNA gene and the ITS1 region of fungal ribosomal DNA across distinct growth stages. The obtained sequencing data provide a robust basis for estimating soil microbial diversity. We observed that, under the intercropping mode, the composition of both bacteria and fungi more closely resembled that of soybean monocropping. The monocropping of red kidney beans increased the richness of rhizosphere bacteria and fungi and promoted the accumulation of pathogenic microorganisms. In contrast, intercropping cultivation and soybean monocropping favored the accumulation of beneficial bacteria such as Bacillus and Streptomyce, reduced pathogenic fungi including Alternaria and Mortierell, and exhibited less microbial variation across different growth stages. Compared to the monocropping of red kidney beans, these systems demonstrated more stable microbial structure and composition. The findings of this study will inform sustainable agricultural practices and soil management strategies. Full article

Soilborne diseases cause losses of 45–70% in faba bean in Ethiopia. Studies were undertaken to define soilborne pathogens and their complexes in Ethiopia. First, the severity of root rot was assessed in 150 field sites across seven Ethiopian regions. Soil samples were collected, and the DNA of 29 pests and pathogens was quantified using a commercial quantitative PCR (qPCR) soil testing service. There was a very high incidence rate of Macrophomina phaseolina, as well as Pythium clades F and I. The other detected species in order of incidence included Fusarium redolens, Rhizoctonia solani, Aphanomyces euteiches, Phytophthora megasperma, Sclerotinia sclerotiorum and S. minor, and Verticillium dahliae, as well as low levels of Thielaviopsis basicola. Five anastomosis groups (AG) of R. solani, namely AG2.1, AG2.2, AG3, AG4, and AG5, were detected, of which AG2.2 and AG4 were most prevalent. We believe this is the first report of occurrence for Ethiopia of A. euteiches, Ph. megasperma, T. basicola, and the five AGs for R. solani. There were very high incidence rates of the foliar pathogens Botrytis cinerea, B. fabae, Didymella pinodes, and Phoma pinodella and of the nematode Pratylenchus thornei, followed by P. neglectus and P. penetrans. The root rot severity and distribution varied significantly across regions, as well as with soil types, soil pH, and soil drainage. Subsequently, metabarcoding of the soil DNA was undertaken using three primer pairs targeting fungi (ITS2), Fusarium species (TEF1 α), and Oomycetes (ITS1Oo). The ITS2 and TEF1α primers emphasized F. oxysporum as the most abundant soilborne fungal pathogen and highlighted F. ananatum, F. brachygibbosum, F. brevicaudatum, F. clavum, F. flagelliforme, F. keratoplasticum, F. napiforme, F. nelsonii, F. neocosmosporiellum, F. torulosum, and F. vanettenii as first reports of occurrence for Ethiopia. The ITS1Oo primer confirmed Pythium spp. as the most prevalent of all Oomycetes. Full article

The land-use conversion of Masson pine forests to tea fields is extensively practiced across subtropical China, primarily driven by its economic benefit. However, the effects of this conversion on soil fungal communities and functional guilds are poorly understood. Herein, a field experiment was conducted in a Masson pine forest (F), a 5-year-old tea plantation without (FT-CK) fertilization or with (FT-N), and a 30-year-old tea plantation (FT-O) to assess the impact of Masson pine forest-to-tea conversion on soil fungal abundance, community structure, and functional guilds by using qPCR and high-throughput sequencing. Compared to F, fungal abundance significantly decreased by 95%, 68%, and 79% in FT-CK, FT-N, and FT-O, respectively, probably caused by the decreased total nitrogen content and habitat disruption. Fungal alpha diversity significantly increased in FT-N and FT-O compared to FT-CK. FT-O presented the highest percentages of Mortierella among treatments, which favours soil organic carbon accumulation. FUNGuild-based predictions showed that FT-CK and FT-N had higher relative abundances of plant pathogens than F and FT-O. FT-O presented the highest percentages of litter and soil saprotrophs but exhibited the lowest percentages of ectomycorrhizal fungi among treatments, likely driven by increased soil organic carbon, total nitrogen, and total phosphorus content. Our findings demonstrate that Masson pine forest-to-tea conversion significantly degrades soil fungal community and function, highlighting the urgent need for soil management strategies (e.g., organic amendments) to enhance soil health in tea agroecosystems. Full article

Viticulture is vital to Italy’s agricultural sector, since it significantly contributes to the global wine industry. Microflora and microfauna are considered important factors for soil quality, improving grapevine growth, and promoting resistance to biotic and abiotic stresses. This study examined the impact of selected Trichoderma strains (T. harzianum M10 and T. afroharzianum T22) and their secondary metabolite 6-pentyl-α-pyrone (6PP) on the soil microbiome, the metabolome, and physiological changes of grapevines. Before treatment application, low levels of plant-parasitic nematodes (Rotylenchulus spp., Xiphinema pachtaicum) were found in the soil, together with pathogens (Fusarium spp., Neonectria spp.) and beneficial microbes (Clonostachys rosea, Pseudomonas spp.). Metagenomic analysis revealed significant treatment impacts in the soil microbiome, with T22 and 6PP treatments increasing Proteobacteria abundance, while slight variations of fungal communities and no significant differences in nematofauna were found. Metabolomic analysis showed that treatments induced grapevines to produce antioxidant secondary metabolites able to boost plant defense against abiotic and biotic stresses and increase nutraceutical grapes’ value. Finally, T22 treatment increased the grapes’ winemaking value, raising their Brix grade. Our results demonstrate that microbial or metabolite-based treatments could affect the soil microbiome composition, grapevine health and resilience, and grapes’ oenological and nutraceutical properties. Full article

Plant diseases caused by Rhizoctonia solani present a significant challenge in agriculture. While chemical pesticides remain a common control strategy, their use leads to health and environmental problems. In contrast, endophytic bacteria with plant growth-promoting (PGP) activity offer a promising, sustainable alternative. In this context, a novel endophytic Priestia megaterium strain, KW16, originated from the bluegrass (Poa pratensis L.), demonstrated distinct biocontrol potential against R. solani. in vitro assays showed that KW16 inhibited R. solani growth by up to 58%, primarily by releasing volatile compounds. In planta experiments further highlighted KW16′s ability to colonize oilseed rape internal tissues, significantly enhancing its growth and development. In the presence of the pathogen, KW16 abolished the negative impact of R. solani and promoted plant growth, increasing shoot and root biomass by 216% and 1737%, respectively, when compared to the plants grown in fungal-infested soil. Biochemical and genome analyses confirmed the strain’s metabolic versatility, resistance to biotic and abiotic factors, and a whole spectrum of PGP and biocontrol traits such as biofilm formation, production of phytohormones, and synthesis of lytic enzymes, siderophores, and volatiles, alongside its ability to survive in the presence of autochthonous soil microflora. These findings position KW16 as a potent biological alternative to synthetic fungicides, with significant potential for sustainable crop protection. Full article

Chickpea is a legume that grows in most parts of the world. It is negatively affected by abiotic and biotic factors like drought and fungal diseases, respectively. One of the most important soil-borne pathogens affecting chickpeas is Fusarium oxysporum f.sp. ciceris (Foc). Its population dynamics in the soil are affected by fluctuations in soil water content and host characteristics. For the last three decades, drought has been common in most areas of the world due to global warming. Drought stress decreases the quality and quantity of the chickpeas, particularly where soil-borne pathogens are the main stress factor for plants. The use of both drought-tolerant and disease-resistant cultivars may be the only option for cost-effective yield production. In this study, we screened the seeds of twelve chickpea genotypes WR-315, JG-62, C-104, JG-74, CPS-1, BG-212, ANNIGERI, CHAFFA, BG-215, UC-27, ILC-82, and K-850 for drought tolerance at increasing polyethylene glycol (PEG) concentrations (0-, 5-, 7.5-, 10-, 15-, 20-, 25-, 30- and 50%) to create drought stress conditions at different severities. The performances of genotypes that were previously tested in Foc resistance/susceptibility studies were assessed in terms of percentage of germination, radicle and hypocotyl length, germination energy, germination rate index, mean germination time, and vigor index in drought conditions. We determined the genotypes of C-104, CPS-1, and WR-315 as drought-susceptible, moderately drought-tolerant, and drought-tolerant, respectively. We then elucidated the stress levels of selected genotypes (20-day-old seedlings) at 0–15% PEG conditions via measuring proline and malondialdehyde (MDA) contents. Our findings showed that genotypes that were resistant to Foc also exhibited drought tolerance. The responses of chickpea genotypes infected with Foc under drought conditions are the next step to assess the combined stress on chickpea genotypes. Full article