Soil-borne Diseases Research Articles

IDENTIFICATION OF RESISTANCE TO MELON FUSARIUM WILT IN SEVEN HYBRID COMBINATIONS OF PUMPKINS

Melon wilt disease, also known as wilt disease, occurs from the seedling stage to the adult stage of plants. According to previous research, grafting is an effective means to improve the resistance of melons and Solanaceae vegetables to soil borne diseases and pests. With the popularization of vegetable grafting, the demand for rootstocks has rapidly increased. Therefore, this experiment takes seven pumpkin hybrid combinations as the research object, studies the resistance of different hybrid combinations to wilt disease, selects pumpkin hybrid combination rootstocks with strong resistance, and provides reference for grafting cultivation in production. The research results indicate that 10 days after inoculation with pathogens, the overall plant infection in the early stage was not significantly affected by the pathogens, and there was no significant difference between the various hybrid combinations. On the 20th day of inoculation with pathogens, Yanbian-3×360-3 showed significant differences in plant height and chlorophyll indicators compared to other pumpkin rootstock hybrid combinations. On the 30th day of pathogen inoculation, Yanbian-3×360-3 showed significantly higher plant stem diameter indicators than other pumpkin rootstock hybrid combinations, showing significant differences from other pumpkin hybrid combinations. Therefore, it can be concluded that Yanbian-3×360-3 had the optimal relative growth rate. Moreover, on the 30th day of pathogen inoculation, the leaf disease index was 52.67%, and the stem disease index was 37.92%, indicating that Yanbian-3×360-3 was less affected by pathogen infection and has stronger resistance to wilt disease. On the 30th day after inoculation with pathogenic bacteria, the investigation showed that the disease index of leaves in Yanbian-2×041-1 was 54.67%, and the disease index of stem dissection was 45.83%. Hetoua2×041-1, with a leaf disease index of 95.33% and a stem cutting disease index of 87.92%. Among the seven pumpkin hybrid combinations, Yanbian-3×360-3 and Yanbian-2×041-1 have the best disease resistance and are neutral disease resistant combinations; Hetoua2×041-1 has the most severe incidence and is a highly susceptible combination. The two pumpkin rootstocks, Yanbian-3×360-3 and Yanbian-2×041-1, have good resistance to melon wilt disease and can be used as grafting rootstocks for melon wilt disease resistance. Considering the affinity between grafting rootstocks and scions and the impact on yield after grafting, further verification is needed in the later stage.

Amphiphilic polysiloxane graft guanidine salts with a combination of low environmental toxicity and high antifungal activity

Banana Fusarium wilt is one of the most serious diseases that restricts the banana industry. How to achieve efficient, low toxicity, and long-term inhibition of pathogenic fungal spores (Fusarium oxysporum f. sp. cubense, race 4, Foc4) that grow in soil has become a challenge in the field of chemical control of plant diseases in recent years. Based on the special antimicrobial mechanism of guanidine salts, which can effectively inhibit microbes by forming transmembrane stomata on the plasma membrane, we were inspired to introduce hydrophilic guanidine salts to hydrophobic PDMS chains to potentially balance high antimicrobial activity and low environmental toxicity. In this work, a series of novel amphiphilic polysiloxane graft guanidine salts (PDMS-g-GH) were synthesized based on our previous works, i.e., polysiloxane graft primary amine salts (PDMS-g-AH), in which the primary amine salt groups were converted to guanidine salt groups. The molecular weight of the polymer, the grafting density of guanidine salts, the distribution of guanidine salt units on the main chain (random or block), the in vitro antifungal activities and the anti-Foc4 activities in soil, the adsorption characteristics in soil, and the environmental toxicity after soil adsorption were systematically studied. The results confirmed that compared with PDMS-g-AH, PDMS-g-GH showed stronger antifungal activity against Foc4 and long-term antifungal activity against Foc4 in soil, but its environmental toxicity was significantly reduced. These results support the potential application of PDMS-g-GH for the prevention and control of banana Fusarium wilt and other soil-borne fungal diseases.

Alfalfa Spring Black Stem and Leaf Spot Disease Caused by Phoma medicaginis: Epidemic Occurrence and Impacts.

Alfalfa spring black stem and leaf spot disease (ASBS) is a cosmopolitan soil-borne and seed-borne disease caused by Phoma medicaginis, which adversely affects the yield, and nutritive value and can stimulate production of phyto-oestrogenic compounds at levels that may adversely affect ovulation rates in animals. This review summarizes the host range, damage, and symptoms of this disease, and general features of the infection cycle, epidemic occurrence, and disease management. ASBS has been reported from over 40 countries, and often causes severe yield loss. Under greenhouse conditions, reported yield loss was 31-82% for roots, 32-80% for leaves, 21% for stems and 26-28% for seedlings. In field conditions, the forage yield loss is up to 56%, indicating that a single-cut yield of 5302 kg/ha would be reduced to 2347 kg/ha. P. medicaginis can infect up to 50 species of plants, including the genera Medicago, Trifolium, Melilotus, and Vicia. ASBS is more severe during warm spring conditions before the first harvest than in hot summer and cooler winter conditions, and can infect alfalfa roots, stems, leaves, flowers, pods, and seeds, with leaf spot and/or black stem being the most typical symptoms. The primary infection is caused by the overwintering spores and mycelia in the soil, and on seeds and the cortex of dead and dry stems. The use of resistant cultivars is the most economical and effective strategy for the control of ASBS. Although biological control has been studied in the glasshouse and is promising, chemical control is the main control method in agriculture.

Genetic Diversity of Ralstonia solanacearum Causing Tobacco Bacterial Wilt in Fujian Province and Identification of Biocontrol Streptomyces sp.

Tobacco bacterial wilt is a highly destructive soilborne disease caused by the Ralstonia solanacearum species complex, exhibiting a significant risk to global flue-cured tobacco cultivation and resulting in substantial economic loss. In this study, 77 isolates were collected from three prominent flue-cured tobacco cultivation areas in Fujian, China (Nanping, Sanming, and Longyan), in 2021 and 2022. The isolated strains were classified through phylotype-specific multiplex polymerase chain reaction (Pmx-PCR) and physiological tests. The analysis showed that all the strains were associated with phylotype I, race 1, and biovar III. Subsequent phylogenetic analysis using partial egl gene sequences classified the 77 isolates into 5 distinct sequevars: 13, 15, 16, 17, and 34. Notably, a remarkable predominance of sequevar 15 was observed in Fujian Province, while sequevar 16 was first reported on tobacco in China, which was identified in other plants, expanding the understanding of its host range and distribution in the country. In addition, a Streptomyces strain extracted from the rhizosphere soil of tobacco was found to inhibit the growth of multiple sequevars of tobacco R. solanacearum, indicating its broad-spectrum antagonistic properties. Furthermore, pot experiments showed that the strain St35 effectively controlled tobacco bacterial wilt. The isolate St35 was conclusively identified as Streptomyces gancidicus according to the morphological and genetic features. In summary, the present study demonstrated the genetic diversity and distribution of tobacco R. solanacearum strains in the Fujian province of China, as well as the identification of a candidate biological control agent for the management of tobacco bacterial wilt.

Control of coptis root rot by combination of Bacillus cereus isolate Y9 and other antagonistic microorganisms

Root rot is a destructive soil-borne disease of Coptis chinensis, which depends on chemical control at present, and more attention should be paid to biocontrol of disease. In the present research, isolate Y9 isolated from healthy root samples of Coptis, was identified as Bacillus cereus. Further screening and pot experiments showed that B. cereus isolate Y9 inhibited the growth of the main causal agents of coptis root rot disease (Fusarium solani and F. avenaceum) and seven other phytopathogenic fungi. The application of B. cereus isolate Y9 and compatible Trichoderma harzianum, T. atroviride and B. amyloliquefaciens, singly and in combination were found to be effective against Fusarium root rot in vitro and in field experiments. In field experiments, combinations of T. harzianum + B. amyloliquefaciens + Y9 (HYJ, in ratio of 1:1:1) showed the highest control efficacy of 63.85%, which was higher than the expected value (53.18%), indicating synergistic effect on the control of coptis root rot. Therefore, B. cereus isolate Y9 may be a potential biological control agent, and combined use with T. harzianum and B. amyloquefaciens offered even greater potential. The long-term effects of isolate B. cereus Y9 and its combinations on C. chinensis should be assessed in different locations and seasons in the future.

Screening of the Biocontrol Efficacy of Potent Trichoderma Strains against Fusarium oxysporum f.sp. ciceri and Scelrotium rolfsii Causing Wilt and Collar Rot in Chickpea.

Chickpeas contribute to half of the pulses produced in India and are an excellent source of protein, fibers, carbohydrates, minerals, and vitamins. However, the combination of the wilt and root rot diseases drastically lowers its yield. The use of antagonist microbes that restrict the growth of other phytopathogens is an ecofriendly approach to combat the serious threats raised by the plant pathogens. Trichoderma spp. are well known as biocontrol agents, especially against soil- and seed-borne phytopathogens. In this study, 21 Trichoderma isolates that were collected from different rhizospheric soils were evaluated against two notorious soil-borne pathogens, such as Fusarium oxysproum f.sp. ciceri and Sclerotium rolfsii. The maximum percentage of inhibition against the tested pathogens was observed in Trichoderma isolate PBT13 (72.97%, 61.1%) followed by PBT3 (72.23%, 59.3%). The mycelial extension rate method, dual culture (antagonism), production of cell-wall degrading enzymes (CWDs), and antifungal metabolites (by GC-MS) were used as selection criteria for potent Trichoderma isolates. Among the 21 isolates, PBT3, PBT4, PBT9, and PBT13 exhibited high antagonistic activity, production of antifungal metabolites, and chitinase and β-1,3-glucanase activity. These four species were subjected to molecular characterization using an internal transcribed spacer (ITS 1 and ITS4). The results of molecular characterization identified the four species as T. virnes, T. asperellum, T. lixii, and T. harzianum. Moreover, significant chitinase and β-1,3-glucanase activities of all Trichoderma isolates were recorded in the growth medium. Trichoderma harzianum (isolate PBT13) was found to exhibit the highest chitinase activity in terms of zone formation (4.40 ± 0.17 cm), whereas Trichoderma virens (isolate PBT3) exhibited the highest β-1,3-glucanase activity1.511 μmole/min. A GC-MS analysis of ethyl extracts from two isolates of Trichoderma (PBT9, PBT13) revealed the presence of 28 VOCs. Overall, this study suggests that these four Trichoderma strains are promising biological control agents (BCAs) and could be developed as bio-pesticides after stringent field trials for the management of soil-borne diseases of chickpeas.

A ridge-based detection algorithm with filament overlap identification for 2D mycelium network analysis

Many terrestrial ecosystems engage mycorrhizal symbiotic associations, potentially to enhance nutrition, increase resistance to soil-borne pests and diseases, and improve resilience and soil structure. Mycorrhizal fungi create dynamic networked structures through branching and anastomosis that connect multiple plants and consent to transport resources underground from nutrient-rich patches to demanding plants. Controlled laboratory experiments are fundamental to improving our knowledge of mycelium network growth dynamics and further understanding its role in preserving ecological niches. We propose a method for highly automated analysis of the mycelium network structure and other morphological properties, such as hyphal length, hyphal density, and number of crossing and branches, in 2D microscopy images of fungal samples. Available tools for automated network analyses suffer from overestimating network connectivity since filament crossings are not considered. In particular, we propose a) a ridge-based mycelium detection algorithm and b) a geometrical-based approach to identify overlapping filaments crossing each other. The algorithmic solution is evaluated on a total of 135 real mycelium sample images over different validation steps, originating from different datasets and having different characteristics, including background, contrast, image acquisition system, fungal species, and clearness (e.g., level of transparency, homogeneity, dirtiness of the medium) of the sample. Results show that 1) the proposed detection method can be used to measure the length of mycelium in an image, replacing manual tracing and allowing for less laborious analysis ρ̂c=0.96, 2) the filament detection is on par with state-of-the-art techniques F1=0.88−0.94 with a more intuitive parameterization, and 3) the proposed algorithm correctly identifies filament crossings F1=0.89 in most common cases, yielding a reduction in the overestimation of network connectivity. The latter feature consents to applying the proposed fully automated solution to complex and irregular fungal structures, advancing mycelium detection and reconstruction performance accuracy with respect to the state-of-the-art.

Rhizobacterial Bacillus enrichment in soil enhances smoke tree resistance to Verticillium wilt.

Verticillium wilt, caused by the soilborne fungus Verticillium dahliae, poses a serious threat to the health of more than 200 plant species worldwide. Although plant rhizosphere-associated microbiota can influence plant resistance to V. dahliae, empirical evidence underlying Verticillium wilt resistance of perennial trees is scarce. In this study, we systemically investigated the effect of the soil microbiota on the resistance of smoke trees (Cotinus coggygria) to Verticillium wilt using field, greenhouse and laboratory experiments. Comparative analysis of the soil microbiota in the two stands of smoke trees suggested that Bacillus represented the most abundant and key microbial genus related to potential disease suppression. Smoke tree seedlings were inoculated with isolated Bacillus strains, which exhibited disease suppressiveness and plant growth-promoting properties. Furthermore, repletion of Bacillus agents to disease conducive soil significantly resulted in reduced incidence of smoke tree wilt and increased resistance of the soil microbiota to V. dahliae. Finally, we explored a more effective combination of Bacillus agents with the fungicide propiconazole to combat Verticillium wilt. The results establish a foundation for the development of an effective control for this disease. Overall, this work provides a direct link between Bacillus enrichment and disease resistance of smoke trees, facilitating the development of green control strategies and measurements of soil-borne diseases.

Rotation with other crops slow down the fungal process in tobacco-growing soil

Continuous cultivation of tobacco could cause serious soil health problems, which could cause bacterial soil to change to fungal soil. In order to study the diversity and richness of fungal community in tobacco-growing soil under different crop rotation, three treatments were set up in this study: CK (tobacco continuous cropping); B (barley-tobacco rotation cropping) and R (oilseed rape-tobacco rotation cropping). The results of this study showed that rotation with other crops significantly decreased the soil fungal OTUs, and also decreased the community richness, evenness, diversity and coverage of fungal communities. Among them, B decreased the most. In the analysis of the composition and structure of the fungal community, it was found that the proportion of plant pathogens Nectriaceae decreased from 19.67% in CK to 5.63% in B, which greatly reduced the possibility of soil-borne diseases. In the analysis of the correlation between soil environmental factors and fungal communities, it was found that Filobasidiaceae had a strong correlation with TP and AP, and Erysiphaceae had a strong correlation with TK and AK. NO3−-N and NH4+-N were the two environmental factors with the strongest correlation with fungal communities. The results of this study showed that rotation with other crops slowed down the process of soil fungi in tobacco-growing soil and changed the dominant species of soil fungi community. At the same time, crop rotation changed the diversity and richness of soil fungal community by changing the physical and chemical properties of soil.

Plant growth promotion and biocontrol properties of a synthetic community in the control of apple disease

BackgroundApple Replant Disease (ARD) is common in major apple-growing regions worldwide, but the role of rhizosphere microbiota in conferring ARD resistance and promoting plant growth remains unclear.ResultsIn this study, a synthetic microbial community (SynCom) was developed to enhance apple plant growth and combat apple pathogens. Eight unique bacteria selected via microbial culture were used to construct the antagonistic synthetic community, which was then inoculated into apple seedlings in greenhouse experiments. Changes in the rhizomicroflora and the growth of aboveground plants were monitored. The eight strains, belonging to the genera Bacillus and Streptomyces, have the ability to antagonize pathogens such as Fusarium oxysporum, Rhizoctonia solani, Botryosphaeria ribis, and Physalospora piricola. Additionally, these eight strains can stably colonize in apple rhizosphere and some of them can produce siderophores, ACC deaminase, and IAA. Greenhouse experiments with Malus hupehensis Rehd indicated that SynCom promotes plant growth (5.23%) and increases the nutrient content of the soil, including soil organic matter (9.25%) and available K (1.99%), P (7.89%), and N (0.19%), and increases bacterial richness and the relative abundance of potentially beneficial bacteria. SynCom also increased the stability of the rhizosphere microbial community, the assembly of which was dominated by deterministic processes (|β NTI| > 2).ConclusionsOur results provide insights into the contribution of the microbiome to pathogen inhibition and host growth. The formulation and manipulation of similar SynComs may be a beneficial strategy for promoting plant growth and controlling soil-borne disease.

Distribution of Three Verticillium dahliae Races in Coastal California and Evaluation of Resistance in Lettuce.

Verticillium wilt, caused by Verticillium dahliae, is one of the most devastating soilborne diseases of lettuce (Lactuca sativa L.). There are three races of V. dahliae, and each race has been characterized by markers representing race-specific effectors. Race 1 is differentiated by the presence of the functional secretory Ave1 effector. Similarly, races 2 and 3 are differentiated by effectors VdR2e and VdR3e, respectively. Although the presence of race 1 in coastal California was well established, the presence of effector-based races 2 and 3 was uncertain. This study therefore focused on characterizing 727 isolates collected from 142 ranches of symptomatic lettuce and other crops from coastal California. Based on this evaluation, 523 isolates were designated as race 1, 20 isolates as race 2, 23 isolates as race 3, and 17 as race undefined. Isolates representing other Verticillium species totaled 110, and 34 were non-Verticillium fungal species. Because the use of resistant cultivars is a key strategy to manage this disease, we evaluated 48 lettuce germplasm lines and 1 endive (Cichorium endivia L.) line, comprising commercial cultivars and breeding lines, including the race 1-resistant heirloom cultivar La Brillante and the susceptible cultivar Salinas as controls. Resistance against races 1, 2, and 3 along with VdLs17, a virulent isolate of V. dahliae from lettuce that is currently not assigned to a race, was evaluated in replicated greenhouse experiments. Two crisphead lettuce lines, HL28 and HL29, exhibited resistance against race 1 and a partial resistance against race 2, whereas all other lines were highly susceptible to races 1 and 2 and VdLs17. The majority of lines exhibited higher resistance to race 3 relative to the other two races. This study documents the current distribution of the different races in coastal California. In addition, the sources of resistance currently being developed should be effective or partially effective against these races for targeted deployment as soon as they are available.

Synergistic Action of New Combination of Fungicides in the Management of Tikka Leaf Spot and Rust Diseases in Groundnut

Tikka leaf spot and rust diseases are major constraints in groundnut at Nellore district of Andhra Pradesh. We conducted front line demonstration on effect of new combination of fungicides for management of foliar diseases in groundnut and the experiment was carried out at different farmer’s field. The farmers practicing variety TAG24 is highly susceptible to tikka leaf spot and soil borne diseases. The trial was conducted during rabi season for two years. During rabi, 2022-2023, the percent disease incidence of tikka leaf spot recorded 38.46% in demo plot where as in farmer practice 74.62% recorded. During rabi 2023-2024, recorded 38.8% and 65.4% tikka leaf spot disease in demo plot and farmer practice respectively. The average pod yield was increased 5% more in demo plot over farmer practicing plot. The average of 2 years, rust diseases recorded 5% in demo plot and 16% in farmer practice. In both treatments the incidence of tikka leaf spot was high due to farmers cultivating variety is highly susceptible to foliar diseases and farmers are used higher seed rate i.e. 200kg/acre. Based on results we concluded that the combination fungicides i.e. tebuconozole 50% +trifloxystrobin 25% WG and pyraclostrobin 5% +metiram 55% WG are best chemicals than single mode of action fungicides and time of application of fungicide is also important.

In vivo Studies on the Effect of Warburgia ugandensis Crude Extracts Against Bacterial wilt in Tomato

Tomato plants are susceptible to Ralstonia solanacearum, a pathogen responsible for bacterial wilt, a severe soil-borne disease with no available cure. Warburgia ugandensis crude extract has shown biocontrol capabilities against pathogenic fungi and bacteria in animals, but data on its effectiveness in plants is limited. The current study was done to evaluate the in vivo efficacy of W. ugandensis crude extracts against R. solanacearum in tomato plants. W. ugandensis leaf and stem bark crude extracts were obtained using ethanol, methanol, hexane, and dichloromethane. The obtained crude extracts were tested against R. solanacearum in tomato at the greenhouse in triplicate. The data collected on bacterial wilt incidence, severity, stem diameter, height, and the number of branches and fruits set were analyzed using analysis of variance (ANOVA) at a 5% significance level. Tukey’s test was employed to determine significant differences between means at the same significance level. Tomato plants established in soil inoculated with R. solanacearum and treated with dichloromethane crude extract of W. ugandensis stem bark showed no sign of bacterial wilt disease and were comparable to the positive control. Tomato plants established in soil inoculated with R. solanacearum but treated with W. ugandensis leaf ethanol crude extract had the highest average height of 62.50 cm which was similar to positive control. Tomato plants grown in R. solanacearum-inoculated soils and treated with methanol crude extracts from W. ugandensis stem bark produced a significantly higher average number of fruits, 22.00, compared to those treated with crude extracts from other solvents. The study proposed that W. ugandensis crude extract has the ability to be used as antibacterial biocontrol against R. solanacearum. Further research is important to determine the bioactive compounds against R. solanacearum.

Identification and Fungicide Sensitivity of Fusarium spp. Associated with Root Rot of Scutellaria baicalensis in Shanxi Province, China.

Fusarium root rot is usually classified as an extremely destructive soilborne disease. From 2020 to 2021, Fusarium root rot was observed in production areas and seriously affected the yield and quality of Scutellaria baicalensis in Shanxi Province, China. Based on morphological characteristics and combined analysis of the internal transcribed spacer region of ribosomal DNA and translation elongation factor 1-alpha sequences, 68 Fusarium isolates obtained in this work were identified as F. oxysporum (52.94%), F. acuminatum (20.59%), F. solani (16.17%), F. proliferatum (5.88%), F. incarnatum (2.94%), and F. brachygibbosum (1.47%). In the pathogenicity tests, all Fusarium isolates could infect S. baicalensis roots, presenting different pathogenic ability. Among these isolates, F. oxysporum was found to have the highest virulence on S. baicalensis roots, followed by F. acuminatum, F. solani, F.proliferatum, F. brachygibbosum, and F.incarnatum. According to fungicide sensitivity tests, Fusarium isolates were more sensitive to fludioxonil and difenoconazole, followed by carbendazim, thiophanate-methyl, and hymexazol. In brief, this is the first report of Fusarium species (F. oxysporum, F. acuminatum, F. solani, F. proliferatum, F. incarnatum, and F. brachygibbosum) as causal agents of root rot of S.baicalensis in Shanxi Province, China. The fungicide sensitivity results will be helpful for formulating management strategies of S. baicalensis root rot.

Complete genome sequence of Bacillus velezensis strain Ag109, a biocontrol agent against plant-parasitic nematodes and Sclerotinia sclerotiorum

Soybean is the main oilseed cultivated worldwide. Even though Brazil is the world’s largest producer and exporter of soybean, its production is severely limited by biotic factors. Soil borne diseases are the most damaging biotic stressors since they significantly reduce yield and are challenging to manage. In this context, the present study aimed to evaluate the potential of a bacterial strain (Ag109) as a biocontrol agent for different soil pathogens (nematodes and fungi) of soybean. In addition, the genome of Ag109 was wholly sequenced and genes related to secondary metabolite production and plant growth promotion were mined. Ag109 showed nematode control in soybean and controlled 69 and 45% of the populations of Meloidogyne javanica and Pratylenchus brachyurus, respectively. Regarding antifungal activity, these strains showed activity against Macrophomia phaseolina, Rhizoctonia solani, and Sclerotinia sclerotiorum. For S. sclerotiorum, this strain increased the number of healthy plants and root dry mass compared to the control (with inoculation). Based on the average nucleotide identity and digital DNA-DNA hybridization, this strain was identified as Bacillus velezensis. Diverse clusters of specific genes related to secondary metabolite biosynthesis and root growth promotion were identified, highlighting the potential of this strain to be used as a multifunctional microbial inoculant that acts as a biological control agent while promoting plant growth in soybean.

Synthetic community derived from grafted watermelon rhizosphere provides protection for ungrafted watermelon against Fusarium oxysporum via microbial synergistic effects

BackgroundPlant microbiota contributes to plant growth and health, including enhancing plant resistance to various diseases. Despite remarkable progress in understanding diseases resistance in plants, the precise role of rhizosphere microbiota in enhancing watermelon resistance against soil-borne diseases remains unclear. Here, we constructed a synthetic community (SynCom) of 16 core bacterial strains obtained from the rhizosphere of grafted watermelon plants. We further simplified SynCom and investigated the role of bacteria with synergistic interactions in promoting plant growth through a simple synthetic community.ResultsOur results demonstrated that the SynCom significantly enhanced the growth and disease resistance of ungrafted watermelon grown in non-sterile soil. Furthermore, analysis of the amplicon and metagenome data revealed the pivotal role of Pseudomonas in enhancing plant health, as evidenced by a significant increase in the relative abundance and biofilm-forming pathways of Pseudomonas post-SynCom inoculation. Based on in vitro co-culture experiments and bacterial metabolomic analysis, we selected Pseudomonas along with seven other members of the SynCom that exhibited synergistic effects with Pseudomonas. It enabled us to further refine the initially constructed SynCom into a simplified SynCom comprising the eight selected bacterial species. Notably, the plant-promoting effects of simplified SynCom were similar to those of the initial SynCom. Furthermore, the simplified SynCom protected plants through synergistic effects of bacteria.ConclusionsOur findings suggest that the SynCom proliferate in the rhizosphere and mitigate soil-borne diseases through microbial synergistic interactions, highlighting the potential of synergistic effects between microorganisms in enhancing plant health. This study provides a novel insight into using the functional SynCom as a promising solution for sustainable agriculture.6UoEKpA3MAKccxe2Gy9v1zVideo

Transcriptome analysis reveals the humic acids and chitosan suppressing Alternaria solani growth.

Understanding the inhibitory effects of natural organic substances on soil-borne pathogenic fungi and the relevant molecular mechanisms are highly important for future development of green prevention and control technology against soil-borne diseases. Our study elucidates the inhibitory effect of the combined application of humic acids (HAs) and chitosan on Alternariasolani and the light on the corresponding mechanism. The effect on A. solani growth by HAs incorporated with chitosan was investigated by plate culture and the corresponding mechanism was revealed using transcriptomics. The colony growth of A. solani was suppressed with the highest inhibition rate 33.33% when swine manure HAs was compounded with chitosan at a ratio of 1:4. Chitosan changed the colony morphology from round to irregularly. RNA-seq in the HAs and chitosan (HC) treatment revealed 239 differentially expressed genes compared with the control. The unigenes associated with enzymes activities related to growth and biological processes closely related to mycelial growth and metabolism were downregulated. RNA-seq also revealed that chitosan altered the expression of genes related to secondary metabolism, fungal cell wall formation and polysaccharide synthesis, and metabolism. Meanwhile, weighted gene co-expression network analysis showed that, genes expression in the module positively correlated with mycelial growth was significantly reduced in the HC treatment; and the results were verified by real-time quantitative polymerase chain reaction. The co-inhibition effect of HAs and chitosan on A. solani is associated with downregulated genes expression correlated with mycelial growth.

Microbiological and Mechanism Analysis of Novel Wheat Seed Coating Agents-Induced Growth Promotion of Wheat Seedlings

TFC (10% thifluzamide–fludioxonil–clothianidin) is a novel wheat seed-coating agent. In the field, we confirmed that 10% TFC plays a positive role in preventing soil-borne diseases and promoting wheat seedling growth. However, its effects on rhizosphere microecology and the underlying molecular mechanism are not fully understood. Field trials revealed a positive effect on the biomass, plant height, and root length of wheat sharp eyespots in a Yingshang field, with 95.3% control efficiency. The effects of 10% TFC on the rhizosphere soil microbiome of young wheat plants were evaluated using high throughput sequencing technology. The results demonstrated that seed-coating agents significantly changed bacterial and fungal communities, and reduced the number of bacteria but increased the number of fungi. Sequence analysis revealed that the abundance of Proteobacteria, Actinobacteria, and Patescibacteria in bacteria and Ascomycota, Mortierellomycota, and Basidiomycota in fungi were significantly enriched, which have been reported as being beneficial for plant growth and pathogen resistance. In contrast, the abundance of Mucoromycota in fungi was reduced, and most of the related genera identified were pathogenic to plants. In this study, 15-day-old wheat plant tissues treated with 10% TFC were subjected to global transcriptome analysis by RNA sequencing to provide insights into the effects of 10% TFC on seedling growth. The comparative analysis of Triticum aestivum L. libraries identified 8286 differentially expressed genes (DEGs), of which 2290 and 5996 genes were up- and downregulated in seedling growth in the presence of 10% TFC, respectively. Gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) functional analyses were performed for up- and downregulated DEGs separately, showing that these DEGs were enriched for terms related to the phenylpropanoid biosynthesis pathway, the protein products of which promote cell differentiation and seedling growth. This research provides comprehensive insights into its effects on wheat seedling growth and the rhizosphere microecology of seed coatings and provides important insights into their regulation and into understanding the potential benefits of seed coatings in disease management and plant growth promotion.

Anaerobic soil disinfestation rather than Bacillus velezensis Y6 inoculant suppresses tomato bacterial wilt by improving soil quality and manipulating bacterial communities

Continuous cropping leads to high incidence of soilborne diseases such as bacterial wilt caused by Ralstonia solanacearum, which poses a risk to agricultural production. Anaerobic soil disinfestation (ASD) and plant growth-promoting rhizobacteria (PGPR) are considered environmentally friendly methods to control bacterial wilt. However, the underlying mechanism of the improvement of soil health and the inhibition of bacterial wilt after ASD treatment and PGPR inoculation needs further exploration. This study evaluated the effect of ASD treatment on soil improvement at pre-planting of tomato, and the effect of ASD treatment combined with the application of Bacillus velezensis Y6 (BV) on soil quality, R. solanacearum abundance, and bacterial communities 90 days before harvesting of tomato. The results showed that ASD treatment reduced R. solanacearum abundance in soil by 17.6% pre-planting and 18.7% 90 days before harvesting, but BV inoculation did not influence R. solanacearum abundance. ASD and ASD+BV treatments effectively reduced the occurrence of bacterial wilt, improved soil nutrient status and increased soil microbial activity 90 days before harvesting. Principal co-ordinate analysis showed that the soil bacterial community was significantly influenced by ASD treatment both pre-planting and 90 days before harvesting. Further investigation found that ASD contributed to the enrichment of beneficial flora (Bacillus and Streptomyces). Moreover, pH was an important environmental factor affecting the abundance of R. solanacearum in soil. Co-occurrence network analysis showed that ASD treatment significantly increased network connection of bacterial communities and the proportion of beneficial microorganisms (Proteobacteria and Firmicutes), leading to complex soil bacterial co-occurrence networks both at pre-planting and 90 days before harvesting. Collectively, these results indicate that ASD treatment, but not microbial inoculation can enhance tomato plant resistance to bacterial wilt by improving soil quality and modulating the soil bacterial community.

Exploitation of Grafting for Abiotic and Biotic Stress Management in Vegetable Crops: A Review

Growing vegetables is often impacted by various abiotic and biotic stresses that can hinder growth and yield. Abiotic stresses, such as salinity, water stress, and temperature fluctuations, and biotic stresses, including diseases, pests, and nematodes, pose significant threats to agriculture. Grafting, a horticultural technique, offers a promising solution to overcome these challenges. In cases of salinity stress, grafting with salt-tolerant rootstocks can limit the transport of harmful ions to the shoot and help store them in the roots, mitigating ion toxicity. Water stress, including drought and water logging, can be addressed by grafting with drought-tolerant rootstocks, which can reduce yield losses and enhance photosynthesis under adverse water conditions. Grafting can also improve nutrient uptake, translocation of water, and osmoregulation, thereby assisting plants in surviving under water stress. High and low-temperature stresses, which can disrupt plant metabolism, membrane stability, and growth, can also be addressed through grafting. Grafted plants with temperature-tolerant rootstocks may indirectly enhance tolerance to extreme temperatures. Additionally, grafted plants can adapt to varying temperature conditions by promoting root growth, nutrient absorption, and the production of specific compounds that protect against temperature-related damage. Heavy metal stress, which can contaminate crops and impact human health, can be alleviated by using rootstocks that control the uptake and transport of heavy metals, reducing their toxicity to plants. Furthermore, grafting can effectively combat biotic stresses. By selecting disease-resistant rootstocks, plants can be protected against soil-borne diseases, pests, and nematodes, thereby increasing yields and sustainability in agriculture.