Root Irrigation Research Articles

Exogenous glucose irrigation alleviates cold stress by regulating soluble sugars, ABA and photosynthesis in melon seedlings

Melon (Cucumis melo L.) is an important economic crop and widely planted around the world. Cold stress severely limits its development and yield. Carbohydrates play multiple roles in plant cold tolerance. However, little is known in melon. Based on the metabolome analysis, a total of 635 metabolites were identified upon cold stress in melon seedlings. KEGG analysis shows that differential metabolites were mainly enriched in the glycolysis/gluconeogenesis pathway and pentose phosphate pathway, with glucose being one of the most prominent metabolites. To further investigate the role of glucose in cold tolerance of melon seedlings. We found that root irrigation was more effective than foliar spraying for exogenous glucose application, with optimal concentrations of 0.5% and 1% for cold-tolerant and cold-sensitive genotypes, respectively. Glucose irrigation mainly promoted soluble sugar accumulation to reduce cold damage in melon seedlings. For cold-sensitive genotype, only the sucrose content could be increased, while for cold-tolerant genotype, sucrose, fructose and glucose content could be simultaneously increased. Meanwhile, glucose irrigation recruited ABA not antioxidant enzyme system to cope with cold stress. Hence, glucose watering could improve the maximum photochemical efficiency of seedling photosystem II (Fv/Fm), alleviate physiological drought, reduce the accumulation of malondialdehyde, and accelerated the photosynthetic efficiency of melon seedlings. Based on coefficient of variation and principal component analysis, it was confirmed again that glucose irrigation did alter the strategies for withstanding cold stress and enhance the cold tolerance of melon seedlings. Thus, the results would provide a theoretical basis and feasible measures to protect melon seedings from cold damage.

Bidirectional uptake and redistribution, bio-stimuli responsive xyloglucan-based nanodelivery system for enhanced translocation of non-systemic pesticide in soybean plants

Non-systemic pesticides, like fludioxonil, have the advantages of broad-spectrum and fast-acting, but the limited space of action restricts their effectiveness. This study proposed a nano-delivery strategy (Flu@EXG) by loading fludioxonil on aminated xyloglucan-based nanoparticles (EXG) to enhance the systematicity of fludioxonil in vivo and consequently achieve systemic defense against soybean diseases. The resulting Flu@EXG had an average diameter of 75.6 nm and exhibited responsive release properties to dual-stimuli of hemicellulases and pH value. The combined measurements of target dose and efficacy demonstrated that the Flu@EXG achieved bi-directional uptake and redistribution of fludioxonil, consequently inhibiting both Phytophthora sojae in roots and Botrytis cinerea on leaves meanwhile with a single application method (root irrigation or foliar spraying) in soybean. In contrast, fludioxonil commercial suspensions (Flu SC) hardly reached the roots to control root diseases when applied to foliage. Additionally, the direct inhibition of Flu@EXG against oomycetes was 2.0 times higher than Flu SC at high test concentrations as EXG could directly provide additional membrane damage. Finally, Flu@EXG provided comparable foliar performance to Flu SC and do not affect the growth of soybeans during the test cycle. Thus, the bio-stimuli responsive Flu@EXG nanodelivery system has promising for achieving the systemic prevention by overcoming the spatial and temporal limitations of non-systemic pesticide application, providing new perspectives and technologies for prompting sustainable development of agriculture.

First Report of Root Rot Caused by Fusarium avenaceum and Fusarium flocciferum on Astragalus membranaceus var. mongholicus in China

ABSTRACTAstragalus membranaceus var. mongholicus (Mongolian milkvetch) is one of the most important traditional Chinese medicinal plants. In July 2021, root rot of A. membranaceus var. mongholicus was found in a field in Tongren City, Huangnan Tibetan Autonomous Prefecture, Qinghai Province, China. The aboveground part of the plants exhibited yellowing, wilting and defoliation in severe cases. Seven fungal isolates were obtained, and their pathogenicity, morphology and phylogeny were analysed. A pathogenicity test was performed using the scratch and root irrigation methods, and the results showed that all seven isolates caused root rot on inoculated plants. Based on morphological characteristics and phylogenetic analysis of multi‐locus sequences (ITS, translation elongation factor [TEF‐1α], and RNA polymerase II beta subunit [RPB2] genes), two isolates were identified as Fusarium avenaceum, and five isolates were identified as F. flocciferum. To the best of our knowledge, this is the first report of F. avenaceum and F. flocciferum causing root rot of A. membranaceus var. mongholicus in China.

Melatonin promotes nodule development enhancing soybean nitrogen metabolism under low nitrogen levels

Nitrogen availability profoundly impacts crop productivity, especially for soybeans, which exhibit a substantial demand for nitrogen. In response to the over-reliance on nitrogen fertilizers, which poses both inefficiencies and environmental concerns, the potential of melatonin in enhancing nitrogen uptake and utilization in soybeans through root irrigation was investigated. Melatonin significantly increased the activity of ammonium assimilating enzymes, thereby enhancing plant tolerance to low nitrogen levels, particularly at a concentration of 10 μM. This phenomenon has been conclusively linked to the augmented nitrogen fixation and utilization capacity, attributed to the facilitating rhizobial infection. Notably, melatonin influenced flavonoid content, specifically inducing genistein levels, essential for rhizobial infection. The malonyltransferase-encoding gene GmMaT2, which modifies isoflavones, was found to be crucial for the effects of melatonin on nodulation and nitrogen metabolism. The silence of GmMaT2 hindered the beneficial effects of melatonin on nodule development and attenuated its ability to enhance aspects of low nitrogen tolerance in soybean. It was elucidated that the potential of melatonin as a sustainable strategy for enhancing nitrogen utilization efficiency in soybeans. It provided insights into the underlying mechanisms and underscored the significance of GmMaT2 in mediating the beneficial effects induced by melatonin under low nitrogen conditions. The findings present a promising solution for mitigating agricultural costs and environmental impacts.

Physiological and agronomic response of young ‘Verna’ lemon trees to the application of partial root irrigation compared to conventional deficit irrigation under conditions of high evaporative demand

Physiological and agronomic response of young ‘Verna’ lemon trees to the application of partial root irrigation compared to conventional deficit irrigation under conditions of high evaporative demand

Deep vertical rotary tillage reduced soil salinity and improved seed cotton yield and water productivity under limited irrigation in saline-alkaline fields

Water scarcity and soil salinization severely limit cotton production in arid areas on the globe. A two-season (2020 and 2021) field experiment was performed on cotton under film-mulched drip irrigation in south Xinjiang of China to explore the responses of soil moisture, soil salinity, root growth, seed cotton yield and water productivity to deep vertical rotary tillage (DVRT) depth (T20: 20 cm, T40: 40 cm, T60: 60 cm, Tck: 20 cm, traditional rotary tillage) in saline-alkaline fields under two irrigation amounts (W1:360 mm, W2: 480 mm, local irrigation amount). It was found that the soil moisture storage (0–120 cm) increased with as irrigation amount increased and decreased with increasing DVRT depth. Soil electrical conductivity in the root zone (0–60 cm) and 0–120 cm soil layer declined as irrigation amount and DVRT depth increased. Irrigation amount and DVRT depth had significant effects on root length density, root mass density, root/shoot ratio, and seed cotton yield, all of which increased with increasing irrigation amount and DVRT depth. Under W2, T20, T40 and T60 increased seed cotton yield by 23.3 %, 45.3 %, 65.6 % in 2020, and by 38.9 %, 62.0 % and 84.1 % in 2021 compared with TCK, respectively. Both water productivity and irrigation water productivity increased with increasing DVRT depth. There were significant positive correlations among seed cotton yield and leaf area index, dry matter accumulation, harvest index, root length density, root mass density, root/shoot ratio, water productivity and irrigation water productivity. W1T60 was suggested for cotton production in the saline regions of southern Xinjiang. The DVRT offset the decrease in seed cotton yield under limited irrigation, which indicates that DVRT is promising to reduce soil salinity and improve seed cotton yield and water productivity in saline-alkaline fields for coping with water scarcity and soil salinization.

Dissipation and potential risk of tristyrylphenol ethoxylate homologs in peanuts by spraying and root irrigation: A comparative assessment

Peanuts, known for their nutritional value, health benefits, and delicious taste, are susceptible to agricultural chemical contamination, posing a challenge to the peanut industry in China. While tristyrylphenol ethoxylates (TSPEOs) have garnered attention for their widespread use in pesticide formulations, their dissipation and potential risks in peanuts remain a gap in knowledge. This study, unique in its focus on TSPEOs, investigates their dissipation and potential risks under two common application modes: spraying and root irrigation. The concentration of total TSPEOs in peanut plants was significantly higher when sprayed (435–37,693 μg/kg) than in root irrigation (24–1602 μg/kg). The dissipation of TSPEOs was faster in peanuts and soil when sprayed, with half-lives of 3.67–5.59 d (mean: 4.37 d) and 5.41–7.07 d (mean: 5.95 d), respectively. The residue of TSPEOs in peanut shells and soil were higher with root irrigation (8.9–65.2 and 25.4–305.1 μg/kg, respectively) than with spraying (5.4–30.6 and 8.8–146.5 μg/kg, respectively). These results indicated that the dissipation behavior of TSPEOs in peanuts was influenced by application modes. While the healthy and ecological risk assessments of TSPEOs in soil and peanut shells showed no risks, root irrigation might pose a higher potential risk than spraying. This research provides valuable data for the judicious application of pesticides during peanut cultivation to enhance pesticide utilization and reduce potential risks.

Simultaneously enhancing plant growth and immunity through the application of engineered Bacillus subtilis expressing a microbial pattern1

Simultaneously enhancing plant growth and disease resistance is an ideal goal in Agriculture. Significant efforts have been made to promote plant growth or immunity through the use of biological reagents, such as the application of beneficial microbes and plant immunity inducers. However, balancing plant immunity and growth remains a challenging task. In this study, we engineered the plant growth-promoting bacterium Bacillus subtilis OKB105 to express a secreted microbial pattern, flg22, and accessed its activity in enhancing both plant growth and disease resistance. The OKB105 (flg22) strain exhibited plant growth-promoting activity similar to the OKB105 strain containing an empty vector, OKB105 (EV). Furthermore, the OKB105 (flg22) strain significantly enhanced plant resistance against two distinct pathogens, Pseudomonas syringae DC3000 ΔhopQ1-1 and Phytophthora parasitica, compared to OKB105 (EV), confirming that the engineered OKB105 (flg22) effectively enhances plant disease resistance. Interestingly, root irrigation with OKB105 (flg22) also markedly boosted the plant’s aboveground resistance to pathogens compared to OKB105 (EV). We further demonstrated that OKB105 (flg22) can be applied to confer resistance to pathogens in other plants that recognize flg22. Finally, RNA-Seq and qRT-PCR analyses illustrated that OKB105 (flg22) effectively induced the expression of defense-related genes in pattern-triggered immunity. Our results prove that employing an engineered beneficial microbe expressing a microbial pattern is a promising strategy for simultaneously enhancing plant growth and immunity.

Photodynamic and nitric oxide therapy-based synergistic antimicrobial nanoplatform: an advanced root canal irrigation system for endodontic bacterial infections

BackgroundThe main issues faced during the treatment of apical periodontitis are the management of bacterial infection and the facilitation of the repair of alveolar bone defects to shorten disease duration. Conventional root canal irrigants are limited in their efficacy and are associated with several side effects. This study introduces a synergistic therapy based on nitric oxide (NO) and antimicrobial photodynamic therapy (aPDT) for the treatment of apical periodontitis.ResultsThis research developed a multifunctional nanoparticle, CGP, utilizing guanidinylated poly (ethylene glycol)-poly (ε-Caprolactone) polymer as a carrier, internally loaded with the photosensitizer chlorin e6. During root canal irrigation, the guanidino groups on the surface of CGP enabled effective biofilm penetration. These groups undergo oxidation by hydrogen peroxide in the aPDT process, triggering the release of NO without hindering the production of singlet oxygen. The generated NO significantly enhanced the antimicrobial capability and biofilm eradication efficacy of aPDT. Furthermore, CGP not only outperforms conventional aPDT in eradicating biofilms but also effectively promotes the repair of alveolar bone defects post-eradication. Importantly, our findings reveal that CGP exhibits significantly higher biosafety compared to sodium hypochlorite, alongside superior therapeutic efficacy in a rat model of apical periodontitis.ConclusionsThis study demonstrates that CGP, an effective root irrigation system based on aPDT and NO, has a promising application in root canal therapy.

Biological and physiological effects in Bemisia tabaci feeding on tomatoes endophytically colonized by Beauveria bassiana.

Entomopathogenic fungi (EPF) treatment of plants may affect the survival and feeding preferences of herbivorous pests. However, comprehensive studies on the fitness across their entire life cycle, feeding behavior, and physiological changes in herbivores consuming EPF-treated plants within the tripartite interactions of EPF, plants, and pests are still limited. In this study, we utilized life tables, electrical penetration graph (EPG), and metabolomics to uncover the biological and physiological characteristics of Bemisia tabaci on tomato plants inoculated with Beauveria bassiana through root irrigation. Our study indicated that Beauveria bassiana Bb252 can penetrate the entire tissue from the point of inoculation, primarily colonizing the intercellular spaces and vascular tissue. However, this colonization is temporary, lasting no more than 35 days. Moreover, the population fitness and feeding behavior of Bemisia tabaci on tomato plants treated with Beauveria bassiana via root irrigation were significantly affected, showing a substantial 41.4% decrease in net reproductive rate (R0), a notable reduction in watery salivation, and shortened phloem ingestion. Lastly, we observed a significant decrease in hormones and amino acids of whiteflies that fed on Beauveria bassiana-treated tomato plants by root irrigation. Our results indicated that the endophyte, Beauveria bassiana Bb252, reduced demographic fitness of Bemisia tabaci by altering its hormones and amino acids levels. These findings enhance our understanding of multitrophic interactions in integrated pest management. © 2024 Society of Chemical Industry.

First Report of Root Rot Caused by Fusarium incarnatum on Mongolian Snake gourd in China.

First Report of Root Rot Caused by Fusarium incarnatum on Mongolian Snake gourd in China.

Effects of Selenium on the Lignin Deposition Pattern and Stem Mechanical Properties of Alfalfa (Medicago sativa L.).

Lignin provides structural support to plants; however, it reduces their utilization rate. According to our previous studies, selenium (Se) reduces lignin accumulation in alfalfa, but the specific mechanism involved remains unclear. Therefore, at the seedling stage, four root irrigation treatments using 2.5, 50, and 5 μmol/L sodium selenite (S-RI), selenomethionine (SS-RI), Se nanoparticles (SSS-RI), and deionized water (CK-RI) were performed. At the branching stage, four treatments of foliar spraying with the three Se fertilizers described above at a concentration of 0.5 mmol/L (S-FS, SS-FS, and SSS-FS) and deionized water (CK-FS) were administered. The results revealed that all Se treatments chiefly reduced the level of deposition of syringyl (S) lignin in the first internode of alfalfa stems. SS-FS and SSS-FS treatments mainly reduced the deposition of S and guaiacyl (G) lignins in the sixth internode of alfalfa stems, respectively, while S-FS treatment only slightly reduced the deposition of G lignin. S, SS, and SSS-RI treatments reduced the level of deposition of S and G lignins in the sixth internode of alfalfa stems. Se application increased plant height, stem diameter, epidermis (cortex) thickness, primary xylem vessel number (diameter), and pith diameter of alfalfa but decreased primary xylem area and pith parenchyma cell wall thickness of the first internode, and SS(SSS)-FS treatment reduced the mechanical strength of alfalfa stems. Therefore, Se application could decrease lignin accumulation by regulating the organizational structure parameters of alfalfa stems and the deposition pattern of the lignin monomers.

Synergistic Effects of Chemical Fungicides with Crude Extracts from Bacillus amyloliquefaciens to Control Northern Corn Leaf Blight

In this research, our objective was to investigate the combined impact of microbial extracts and chemical fungicides on Northern corn leaf blight (NCLB), which is induced by Exserohilum turcicum, and the growth-promoting effect of the crude extracts was also determined. NCLB poses a serious threat to global maize production, necessitating sustainable and environmentally friendly solutions. Mycelial growth rate assays were used to assess the single or synergistic effects of microbial crude extracts and chemical fungicides, and the seed-soaking and root irrigation method was used to detect the growth-promoting effect of the crude extracts on maize seedlings. The results revealed an 84.60% inhibition rate of B. amyloliquefaciens gfj-4 against E. turcicum, and with an EC50 of 49.01 mg·L−1 for the crude extracts. Chemical fungicides demonstrated varying toxicity levels, with fludioxonil exhibiting the highest potency. The mixture of the crude extracts and pyraclostrobin at an 8:2 volume ratio displayed the highest toxicity ratio of 1.24, indicating a synergistic effect. The selected combinations exhibited strong synergistic effects. Soaking maize seeds with 80 mg·L−1 of the crude extracts followed by root irrigation with 40 mg·L−1 produced the most significant growth-promoting effect on maize seedlings. This study highlights the potential of microbial crude extracts to enhance the control of NCLB when combined with pyraclostrobin, along with its growth-promoting effects on maize seedlings.

Influence of Fertilization Methods and Types on Wheat Rhizosphere Microbiome Community and Functions.

To investigate the effects of fertilization methods and types on wheat rhizosphere microorganisms, macroelement (N, K) and microelement (Zn) fertilizers were applied on wheat by foliar spraying (FS) and root irrigation (RI) methods in a field experiment. The results indicated that fertilization methods and types can have significant impacts on the diversity and structure of rhizospheric microorganisms in wheat. The application method produced more significant effects than the fertilizer type. RI-N played a more important role in improving the wheat yield and quality and affected the changes in some nitrogen-fixing bacterial communities. Finally, eight strains of bacteria belonging to Pseudomonas azotoformans and P. cedrina showed positive effects on the growth of wheat seedlings. Overall, our study provides a better understanding of the dynamics of wheat rhizosphere microbial communities and their relation to fertilization, yield, and quality, showing that plant growth-promoting rhizobacteria with nitrogen fixing may be a potential approach for more sustainable agriculture production.

Fulvic Acid Promotes Legume-Rhizobium Symbiosis by Stimulating Endogenous Flavonoids Synthesis and Secretion.

Fulvic acid (FA) promotes symbiosis between legumes and rhizobia. To elucidate from the aspect of symbiosis, the effects of root irrigation of water-soluble humic materials (WSHM) or foliar spraying of its highly active component, FA, on soybean root exudates and on rhizosphere microorganisms were investigated. As a result, WSHM/FA treatments significantly altered root exudate metabolite composition, and isoflavonoids were identified as key contributors in both treatments compared to the control. Increased expression of genes related to the isoflavonoid biosynthesis were validated by RT-qPCR in both treatments, which notably elevated the synthesis of symbiotic signals genistein, daidzin, coumestrol, and biochanin A. Moreover, the WSHM/FA treatments induced a change in rhizosphere microbial community, coupled with an increase in the relative abundance of rhizobia. Our findings showed that WSHM/FA promotes symbiosis by stimulating the endogenous flavonoid synthesis and leads to rhizobia accumulation in the rhizosphere. This study provides new insights into mechanisms underlying the FA-mediated promotion of symbiosis.

Streptomyces-triggered coordination between rhizosphere microbiomes and plant transcriptome enables watermelon Fusarium wilt resistance.

The use of microbial inoculant is a promising strategy to improve plant health, but their efficiency often faces challenges due to difficulties in successful microbial colonization in soil environments. To this end, the application of biostimulation products derived from microbes is expected to resolve these barriers via direct interactions with plants or soil pathogens. However, their effectiveness and mechanisms for promoting plant growth and disease resistance remain elusive. In this study, we showed that root irrigation with the extracts of Streptomyces ahygroscopicus strain 769 (S769) solid fermentation products significantly reduced watermelon Fusarium wilt disease incidence by 30% and increased the plant biomass by 150% at a fruiting stage in a continuous cropping field. S769 treatment led to substantial changes in both bacterial and fungal community compositions, and induced a highly interconnected microbial association network in the rhizosphere. The root transcriptome analysis further suggested that S769 treatment significantly improved the expression of the MAPK signalling pathway, plant hormone signal transduction and plant-pathogen interactions, particular those genes related to PR-1 and ethylene, as well as genes associated with auxin production and reception. Together, our study provides mechanistic and empirical evidences for the biostimulation products benefiting plant health through coordinating plant and rhizosphere microbiome interaction.

Effects of plant growth-promoting rhizobacteria on blueberry growth and rhizosphere soil microenvironment.

Plant growth-promoting rhizobacteria (PGPR) have a specific symbiotic relationship with plants and rhizosphere soil. The purpose of this study was to evaluate the effects of PGPR on blueberry plant growth, rhizospheric soil nutrients and the microbial community. In this study, nine PGPR strains, belonging to the genera Pseudomonas and Buttiauxella, were selected and added into the soil in which the blueberry cuttings were planted. All the physiological indexes of the cuttings and all rhizospheric soil element contents were determined on day 6 after the quartic root irrigation experiments were completed. The microbial diversity in the soil was determined using high-throughput amplicon sequencing technology. The correlations between phosphorus solubilization, the auxin production of PGPR strains, and the physiological indexes of blueberry plants, and the correlation between rhizospheric microbial diversity and soil element contents were determined using the Pearson's correlation, Kendall's tau correlation and Spearman's rank correlation analysis methods. The branch number, leaf number, chlorophyllcontentand plant height of the treated blueberry group were significantly higher than those of the control group. The rhizospheric soil element contents also increased after PGPR root irrigation. The rhizospheric microbial community structure changed significantly under the PGPR of root irrigation. The dominant phyla, except Actinomycetota, in the soil samples had the greatest correlation with phosphorus solubilization and the auxin production of PGPR strains. The branch number, leaf number, and chlorophyllcontent had a positive correlation with the phosphorus solubilization and auxin production of PGPR strains and soil element contents. In conclusion, plant growth could be promoted by the root irrigation of PGPR to improve rhizospheric soil nutrients and the microenvironment, with modification of the rhizospheric soil microbial community. Plant growth could be promoted by the root irrigation of PGPR to improve rhizospheric soil nutrients and the microenvironment, with the modification of the rhizospheric soil microbial community. These data may help us to better understand the positive effects of PGPR on blueberry growth and the rhizosphere soil microenvironment, as well as provide a research basis for the subsequent development of a rhizosphere-promoting microbial fertilizer.

Trichoderma spp. promotes ginseng biomass by influencing the soil microbial community.

Ginseng (Panax ginseng C.A. Meyer) has multiple effects on human health; however, soil degradation seriously affects its yield. Trichoderma spp. play an important role in improving plant biomass by influencing the soil environment. Therefore, it is necessary to screen efficient Trichoderma strains that can increase ginseng biomass and determine their mechanisms. Herein, we selected six Trichoderma species (T. brevicompactum, T. velutinum, T. viridescens, T. atroviride, T. koningiopsis, and T. saturnisporum) isolated from ginseng rhizosphere soil, and evaluated their growth promoting effects on ginseng and their influence on the microbiome and chemical attributes of the ginseng rhizosphere soil. Except for T. saturnisporum (F), compared with the control, the other five species increased ginseng biomass. In terms of chemical properties, the pH value, available potassium content, and available phosphorus content in the ginseng rhizosphere soil increased by 1.16-5.85%, 0.16-14.03%, and 3.92-38.64%, respectively, after root irrigation with spores of Trichoderma species. For the soil microbiome, fungal Chao1 and Ace richness indices decreased. Application of Trichoderma enhanced the relative level of Proteobacteria, but reduced the relative level of Ascomycota. At the genus level, application of Trichoderma enhanced the relative levels of Sphingomonas, Blastomonas, and Trichoderma, but reduced the relative level of Fusarium. Available K and available P were the most important elements that affected the structure of the bacterial community, while total K was the most influential element for the structure of the fungal community structure. The results indicated that the application of Trichoderma spp. could increase soil nutrients and regulate the structure and composition of the soil microbial community, thereby enhancing the biomass of ginseng. The results will provide guidance for soil improvement in ginseng cultivation.

First record of Aspergillus nomiae as a broad-spectrum entomopathogenic fungus that provides resistance against phytopathogens and insect pests by colonization of plants.

Aspergillus nomiae is known as a pathogenic fungus that infects humans and plants but has never been reported as an entomophagous fungus (EPF) that can provide other functions as an endotype. A strain of EPF was isolated and identified from diseased larvae of Spodoptera litura in a soybean field and designated AnS1Gzl-1. Pathogenicity of the strain toward various insect pests was evaluated, especially the ability to colonize plants and induce resistance against phytopathogens and insect pests. The isolated EPF strain AnS1Gzl-1 was identified as A. nomiae; it showed strong pathogenicity toward five insect pests belonging to Lepidoptera and Hemiptera. Furthermore, the strain inhibited the growth of Sclerotinia sclerotiorum in vitro, a causal agent of soil-borne plant disease. It colonized plants as an endophyte via root irrigation with a high colonization rate of 90%, thereby inducing plant resistance against phytopathogen infection, and disrupting the feeding selectivity of S. litura larvae. This is the first record of a natural infection of A. nomiae on insects. A. nomiae has the potential to be used as a dual biocontrol EPF because of its ability to not only kill a broad spectrum of insect pests directly but also induce resistance against phytopathogens via plant colonization.

Biocontrol effect of the complex inoculants of Trichoderma and Bacillus amyloliquefaciens on chrysanthemum white rust

In this study, the Chrysanthemum morifolium susceptible cultivar ‘Jinba’ was used as the experimental material to perform prevention and treatment testing of complex inoculants of Trichoderma on chrysanthemum white rust (CWR) and growth promotion and disease-prevention testing of Bacillus amyloliquefaciens. The treatment test results showed that the number of teliospores in the diseased leaves treated with the complex inoculants of Trichoderma was considerably reduced, and the germination of teliospores was inhibited. The results of the prevention experiment showed that test group two (T2) significantly reduced the infection rate of pathogens and enhanced the SOD, POD, CAT, PPO, PAL and CHI compared to the control group and test group one (T1). The RT-qPCR results revealed that T2 could induce the up-regulation of the NPR1, PAL, COI1, and PDF1.2 genes. The treatment of B. amyloliquefaciens root irrigation promoted the growth of ‘Jinba’. The plant height, fresh aboveground weight, fresh underground weight, root-shoot ratio, and root activity increased by 5.38%, 31.67%, 64.63%, 5.26%, and 283.33%, respectively. Moreover, the activities of soil protease, urease, sucrase, and phosphatase increased significantly. The incidence of CWR in the field decreased by 20.0%. In summary, the complex inoculants of Trichoderma can significantly inhibit the germination of teliospores, reduce the infection rate of pathogens and improve the resistance of CWR by inducing the enhancement of related enzyme activity and the up-regulation of disease-resistant gene expression. B. amyloliquefaciens can promote plant growth by increasing soil enzyme activity, thereby reducing the incidence of CWR.