ABSTRACTHosta (Hosta plantaginea L.) is a perennial herbaceous plant belonging to the family Liliaceae. It is widely cultivated for its decorative foliage and dainty, colourful flowers. Fusarium is a globally prevalent plant pathogen. During 2020–2021, 116 Fusarium isolates were isolated from 300 hosta leaf blight samples collected from eight cities in China, and 65 representative isolates we selected for further study. The 65 isolates were identified based on the concatenated sequences of the tef1 and rpb2 genes, which grouped them into 12 Fusarium species, including F. acuminatum (27.59%), F. verticillioides (15.52%), F. oxysporum (10.34%), F. armeniacum (10.34%), F. ipomoeae (8.62%), F. proliferatum (6.9%), F. subglutinans (6.9%), F. humuli (3.45%), F. petersiae (3.45%), F. brachygibbosum (3.45%), F. graminearum (1.72%), and F. compactum (1.72%). Pathogenicity tests demonstrated that all Fusarium isolates exhibited high pathogenicity towards hosta leaves. Whereas in F. proliferatum isolates were found to be the most pathogenic. All Fusarium species obtained in this study are first reported as the causal agents of hosta leaf blight in China except F. oxysporum and F. ipomoeae. The current research offers insights into disease management, phylogenetic relationships amongst Fusarium species and the diversity of Fusarium species associated with hosta leaf blight.

Actinobacteria are widely used in aerobic composting of straw waste because of their good degradation effect on lignocellulose. However, there are few studies on the degradation effect of Glycomyces on straw. In this study, six laboratory-scale treatments were conducted: corn straw composting with Glycomyces inoculation (CSI), rice straw composting with Glycomyces inoculation (RSI), and wheat straw composting with Glycomyces inoculation (WSI). Additionally, composting control groups were set up for each type of straw without inoculation: corn straw (CS), rice straw (RS), and wheat straw (WS). Subsequently, a series of chemical analyses and enzymological methods were used to assess the effects of Glycomyces inoculation on environmental variables, enzyme activities, and organic components. Also, high-throughput sequencing was employed to explore the microbial community composition that greatly contributed to the degradation rate of cellulose and hemicellulose during the degradation process of wheat straw. Finally, the factors influencing the cellulose and hemicellulose degradation in WSI were identified using structural equation models (SEMs). The results showed that cellulose and hemicellulose degradation rates were higher in the Glycomyces-inoculated treatment groups than in the non-inoculated groups. Importantly, the degradation rates of cellulose and hemicellulose in WSI were the highest, at 68.09% and 66.81%, respectively. Collectively, total nitrogen and the microbial community structure of the top 30 genera contributing to cellulose and hemicellulose degradation were important factors influencing the straw degradation of WSI. This study not only provides new insights into the regulation of wheat straw degradation, but also has great significance for environmental protection.

Guvermectin, a purine nucleoside natural product produced by the genus Streptomyces, has recently been registered as a new biopesticide to boost rice yield. Despite its economic and agricultural significance, the regulatory mechanisms of guvermectin biosynthesis remain essentially unknown, hindering industrial production and widespread agricultural application. Here, we examined the roles of two LacI family regulators, gvmR and gvmR2, located within and adjacent to the guvermectin biosynthesis cluster, respectively, in guvermectin production in Streptomyces caniferus NEAU6. GvmR activated the expression of the guvermectin cluster by binding to the promoters of gvmR, gvmA, and O1, while GvmR2 repressed the guvermectin cluster via competitive binding to promoters containing GvmR-binding sites, specifically, a 14-bp palindromic sequences: 5 '-RTCATWCGYATGAY-3 ' (R = G/A, W = A/T, Y = T/C). Moreover, GvmR indirectly activates the expression of gvmR2 while GvmR2 feedback inhibits gvmR transcription, suggesting a functional interaction between the two regulators for coordinating guvermectin production. Overexpression of gvmR via the T7 RNA polymerase-T7 promoter system in the gvmR2 mutant significantly elevated guvermectin production by 125 % (from 631 mg L-1 to 1422 mg L-1), compared to the parental strain NEAU6. This suggested that combinatorial manipulation of gvmR and gvmR2 is useful for improving guvermectin production. These findings enrich our knowledge of the regulatory network for guvermectin biosynthesis, and offer key targets and effective strategies for high-titer guvermectin production.

Kiwiberry (Actinidia arguta) is one of the most nutritious fruits in China, with edible and traditional medicinal values. Brown rot, caused by different species of Monilia, is a common and severe postharvest disease of fruit. In September and October 2023, kiwiberry brown rot was observed in several fruit supermarkets in Harbin, Heilongjiang Province. Fungal isolates were obtained from the edges of lesions on fruit with typical symptoms and identified as M. yunnanensis on the basis of morphological characteristics (colonies and conidia) and multi-locus phylogenetic analyses (ITS, TUB, and lcc2). Pathogenicity experiments showed that M. yunnanensis was able to infect kiwiberry fruit and cause symptoms of brown rot, demonstrating that M. yunnanensis was the causal agent of kiwiberry brown rot. In the present study, we reported for the first time that M. yunnanensis was the causative agent of kiwiberry brown rot, thus laying the foundation for the subsequent development of reasonable and effective postharvest fruit control measures.

Two pink- pigmented bacteria, designated strains NEAU- 140T and NEAU- KT, were isolated from field soil collected from Linyi, Shandong Province, PR China. Both isolates were aerobic, Gram- stain- negative, rod- shaped, and facultatively methylotrophic. 16S rRNA gene sequences analysis showed that these two strains belong to the genus Methylobacterium. Strain NEAU-140T exhibited high 16S rRNA gene sequence similarities to Methylobacterium radiotolerans NBRC 15690T (97.43%) and Methylobacterium phyllostachyos NBRC 105206T (97.36 %). Strain NEAU- KT exhibited high 16S rRNA gene sequence similarities to M. phyllostachyos NBRC 105206T (99.00 %) and Methylobacterium longum DSM 23933T (98.72%). A phylogenetic tree based on 16S rRNA gene sequences showed that strain NEAU- 140T formed a clade with Methylobacterium aerolatum (95.94%), Methylobacterium persicinum (95.66 %) and Methylobacterium komagatae (96.87 %), and strain NEAU-KT formed a cluster with M. phyllostachyos and M. longum. The predominant fatty acid in both strains was C18:1 omega 7c. Both strains contained ubiquinone Q- 10 as the only respiratory quinone. The polar lipid profiles of both strains contained diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylcholine. Whole- genome phylogeny showed that strains NEAU-140T and NEAU- KT formed a phyletic line with M. aerolatum, M. persicinum, Methylobacterium radiotolerans, Methylobacterium fujisawaense, Methylobacterium oryzae, Methylobacterium tardum, M. longum and M. phyllostachyos. The orthologous average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain NEAU- 140T and its closely related strains were lower than 82.62 and 25.90 %, respectively. The ANI and dDDH values between strain NEAU-KT and its closely related strains were lower than 86.29 and 31.7 %, respectively. The genomic DNA G+C contents were 71.63 mol% for strain NEAU- 140T and 69.08 mol% for strain NEAU- KT. On the basis of their phenotypic and phylogenetic distinctiveness and the results of dDDH and ANI hybridization, these two isolates represent two novel species within the genus Methylobacterium, for which the names Methylobacterium amylolyticum sp. nov. (type strain NEAU- 140T=MCCC 1K08801T=DSM 110568T) and Methylobacterium ligniniphilum sp. nov. (type strain NEAU- KT=MCCC 1K08800T=DSM 110567T) are proposed.

Red Guava is widely grown in numerous parts of southern China and is a favorite fruit among Chinese consumers due to its imperative nutritional value, high medicine value and excellent economic value. Black spot is one of the serious diseases that causes fruits rot. In July 2023, 25–30% of postharvest red guava fruits rot exhibiting disease symptoms were observed in surrounding markets of Haikou city, Hainan province, China. The purpose of this study was to isolate and identify the pathogenic fungi of red guava black spot. A total of 26 pathogenic fungal strains were isolated from the rotten red guava fruits with typical characteristics. One representative isolate, FSL2, was selected for subsequent experiments. Combining morphological analysis with phylogenetic analysis (internal transcribed spacer regions 4 and 5, translation elongation factor1, and β-tubulin genes), the pathogens should be identified as Neopestalotiopsis saprophytica. Pathogenic tests indicated that the symptoms of red guava fruit decay caused by N. saprophytica isolated from the sample were almost the same. The fungal species has been previously reported in China on Persimmon related with fruits rot. Thus, this study concluded that the pathogen of red guava black spot may be N. saprophytica. To best of our knowledge, this is the first report of red guava black spot caused by N. saprophytica.

Guvermectin, as a novel nucleoside-like biopesticide, could increase the rice yield excellently, but the potential environmental behaviors remain unclear, which pose potential health risks. Therefore, the uptake and biotransformation of guvermectin in three types of crops (rice, lettuce, and carrot) were first evaluated with a hydroponic system. Guvermectin could be rapidly absorbed and reached equilibrium in roots (12-36 h) and shoots (24-60 h) in three plants, and guvermectin was also vulnerable to dissipation in roots (t1/2 1.02-3.65 h) and shoots (t1/2 9.30-17.91 h). In addition, 8 phase I and 2 phase II metabolites, transformed from guvermectin degradation in vivo and in vitro exposure, were identified, and one was confirmed as psicofuranine, which had antibacterial and antitumor properties; other metabolites were nucleoside-like chemicals. Molecular simulation and quantitative polymerase chain reaction further demonstrated that guvermectin was metabolized by the catabolism pathway of an endogenous nucleotide. Guvermectin had similar metabolites in three plants, but the biotransformation ability had a strong species dependence. In addition, all the metabolites exhibit neglectable toxicities (bioconcentration factor <2000 L/kg b.w., LC50,rat > 5000 mg/kg b.w.) by prediction. The study provided valuable evidence for the application of guvermectin and a better understanding of the biological behavior of nucleoside-like pesticides.

A novel actinobacterial strain (NEAU-HV9T) showing antibacterial activity against Ralstonia solanacearum and herbicidal activity against Amaranthus retroflexus L. was isolated from soil sampled in Bama yao Autonomous County, Hechi City, Guangxi Zhuang Autonomous Region. The strain is aerobic and Gram-positive. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain NEAU-HV9T belonged to the genus Streptomyces and showed high 16S rRNA sequence similarity to Streptomyces panaciradicis 1MR-8T (98.90 %), Streptomyces sasae JR-39T (98.89 %) and Streptomyces barringtoniae JA03T (98.69 %) and less than 98.5 % similarity to other members of the genus Streptomyces. The cell wall of strain NEAU-HV9T contained ll-diaminopimelic acid and the whole-cell hydrolysates were galactose, mannose and ribose. The predominant menaquinones were composed of MK-9(H2) and MK-9(H8). The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol. The major fatty acids were C16 : 0, iso-C16 : 0 and C17 : 1  ω8c. The genomic DNA G+C content of strain NEAU-HV9T was 70.6 mol%. Furthermore, the strain could be clearly distinguished from its closely related type strains by the combination of DNA-DNA hybridization results and some phenotypic characteristics. Meanwhile, strain NEAU-HV9T displayed herbicidal activity. Therefore, strain NEAU-HV9T represents a novel species within the genus Streptomyces, for which the name Streptomyces herbicida sp. nov. is proposed, with strain NEAU-HV9T (=CCTCC AA 2019088T=DSM 113364T) as the type strain.

Gray mold, caused by Botrytis cinerea, is a prevalent postharvest disease of apple that limits their shelf life, resulting in significant economic losses. The use of antagonistic microorganisms has been shown to be an effective approach for managing postharvest diseases of fruit. In the present study, an endophytic yeast strain PGY-2 was isolated from apples and evaluated for its biocontrol efficacy against gray mold and its mechanisms of action. Results indicated that strain PGY-2, identified as Bullera alba, reduced the occurrence of gray mold on apples and significantly inhibited lesion development in pathogen-inoculated wounds. Gray mold control increased with the use of increasing concentrations of PGY-2, with the best disease control observed at 108 cells/mL. Notably, Bullera alba PGY-2 did not inhibit the growth of Botrytis cinerea in vitro indicating that the yeast antagonist did not produce antimicrobial compounds. The rapid colonization and stable population of PGY-2 in apple wounds at 4 °C and 25 °C confirmed its ability to compete with pathogens for nutrients and space. PGY-2 also had a strong ability to form a biofilm and enhanced the activity of multiple defense-related enzymes (POD, PPO, APX, SOD, PAL) in host tissues. Our study is the first time to report the use of Bullera alba PGY-2 as a biocontrol agent for postharvest diseases of apple and provide evidence that Bullera alba PGY-2 represents an endophytic antagonistic yeast with promising biocontrol potential and alternative to the use of synthetic, chemical fungicides for the control of postharvest gray mold in apples.

A Gram-stain-negative, rod-shaped, indole-producing, and cellulose-degrading bacterial strain, designated NEAU-G-C5T, was isolated from soil collected from a forest in Dali city, Yunnan province, south China. 16S rRNA gene sequence analysis showed that strain NEAU-G-C5T was assigned to the genus Massilia and showed high sequence similarities to Massilia phosphatilytica 12-OD1T (98.32 %) and Massilia putida 6 NM-7T (98.41 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-G-C5T formed a lineage related to M. phosphatilytica 12-OD1T and M. putida 6 NM-7T. The major fatty acids of the strain were C16 : 0, C16 : 1 ω7c, and C17 : 0 cyclo. The respiratory quinone was Q-8. The polar lipid profile of the strain showed the presence of diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. In addition, the average nucleotide identity values between strain NEAU-G-C5T and its reference strains M. phosphatilytica 12-OD1T, M. putida 6 NM-7T, M. norwichensis NS9T, and M. kyonggiensis TSA1T were 89.7, 88.2, 81.3, and 88.0 %, respectively, and the levels of digital DNA–DNA hybridization between them were found to be 58.5 % (54.9–62.0 %), 53.2 % (49.8–56.7 %), 31.9 % (28.6–35.5 %), and 57.7 % (54.1–61.2 %), respectively, which were lower than the accepted threshold values of 95–96 % and 70 %, respectively. The DNA G+C content of strain NEAU-G-C5T was 66.5 mol%. The strain could produce indoleacetic acid and cellulase. On the basis of the phenotypic, genotypic, and chemotaxonomic characteristics, we conclude that strain NEAU-G-C5T represents a novel species of the genus Massilia, for which the name Massilia luteola sp. nov. is proposed. The type strain is NEAU-G-C5T (=MCCC 1K08668T=KCTC 8080T).

Bacterial diseases caused substantial yield losses worldwide, with the rise of antibiotic resistance, there is a critical need for alternative antibacterial compounds. Natural products (NPs) from microorganisms have emerged as promising candidates due to their potential as cost-effective and environmentally friendly bactericides. However, the precise mechanisms underlying the antibacterial activity of many NPs, including Guvermectin (GV), remain poorly understood. Here, we sought to explore how GV interacts with Guanosine 5 ' monophosphate synthetase (GMPs), an enzyme crucial in bacterial guanine synthesis. We employed a combination of biochemical and genetic approaches, enzyme activity assays, site-directed mutagenesis, bio-layer interferometry, and molecular docking assays to assess GV's antibacterial activity and its mechanism targeting GMPs. The results showed that GV effectively inhibits GMPs, disrupting bacterial guanine synthesis. This was confirmed through drug-resistant assays and direct enzyme inhibition studies. Bio-layer interferometry assays demonstrated specific binding of GV to GMPs, with dependency on Xanthosine 5 '-monophosphate. Site-directed mutagenesis identified key residues crucial for the GV-GMP interaction. This study elucidates the antibacterial mechanism of GV, highlighting its potential as a biocontrol agent in agriculture. These findings contribute to the development of novel antibacterial agents and underscore the importance of exploring natural products for agricultural disease management.

A novel mycelium-forming actinomycete, designated strain NEAU-S30 T , was isolated from the sandy soil of a sea beach in Shouguang city, Shandong province, PR China. The strain developed long chains of non-motile cylindrical spores with smooth surfaces on aerial mycelia. The results of a polyphasic taxonomic study indicated that NEAU-S30 T represented a member of the genus Glycomyces . The results of 16S rRNA gene sequence analysis indicated that NEAU-S30 T was closely related to ‘ Glycomyces luteolus ’ (98.97 % sequence similarity), Glycomyces algeriensis (98.90 %), ‘ Glycomyces tritici ’ (98.83 %) and Glycomyces lechevalierae (98.76 %). The average nucleotide identity (ANI) values between NEAU-S30 T and ‘ G. luteolus ’ NEAU-A15, G. algeriensis DSM 44727 T , ‘ G. tritici ’ NEAU-C2 and G. lechevalierae DSM 44724 T were 87.77, 87.53, 87.41 and 87.80 %, respectively. The digital DNA G+C content of the genomic DNA was 70.5 %. The whole-cell sugars contained ribose and xylose. The predominant menaquinones were MK-10(H 2 ), MK-10(H 4 ) and MK-10(H 6 ). The predominant fatty acids were anteiso-C 15 : 0 , iso-C 16 : 0 , anteiso-C 17 : 0 and iso-C 15 : 0 . The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified glycolipid. On the basis of the results of comparative analysis of genotypic, phenotypic and chemotaxonomic data, the novel actinomycete strain NEAU-S30 T (=JCM 33975 T =CGMCC 4.7890 T ) represents the type strain of a novel species within the genus Glycomyces , for which the name Glycomyces niveus sp. nov. is proposed.

Soybean is an important protein and oil crop around the world, widely cultivated in Heilongjiang province, China. In the summer of 2021, soybean root rot samples were collected from farms in multiple regions of Heilongjiang province to isolate pathogens. Twenty-seven fungal isolates with similar morphology were found, causing soybean root discolouration and blackness leading to root rot, but which had relatively mild pathogenicity, with an average disease index of 13.69-32.25. Morphological features and multilocus phylogenetic analyses divided these isolates into four species: Clonostachys rosea (48.2%), C. rosea f. sp. rosea (14.8%), C. chloroleuca (29.6%) and Clonostachys sp. (7.4%). Co-inoculation of these four species with two important pathogenic Fusarium species that can cause soybean root rot, F. annulatum and Fusarium sp. 1 in the Fusarium oxysporum species complex (FOSC), showed that C. rosea and Clonostachys sp. significantly reduced the pathogenicity of F. annulatum to soybean root, while C. rosea f. sp. rosea and C. chloroleuca slightly increased the pathogenicity of F. annulatum. C. rosea, Clonostachys sp., C. chloroleuca and C. rosea f. sp. rosea slightly reduced the pathogenicity of Fusarium sp. 1 in the FOSC. Our research is the first to report Clonostachys sp., C. chloroleuca and C. rosea f. sp. rosea causing soybean root rot in Heilongjiang province, China, and that these four Clonostachys species can affect the pathogenicity of Fusarium species, alleviating or aggravating soybean root rot. The findings of this study provide new insights into exploring the interactions between pathogens and thus effectively controlling them.

Temperature is the critical factor affecting the efficiency and cost of anaerobic digestion (AD). The current work develops a shift-temperature AD (STAD) between 35 degrees C and 55 degrees C, intending to optimise microbial community and promote substrate conversion. The experimental results showed that severe inhibition of biogas production occurred when the temperature was firstly increased stepwise from 35 degrees C to 50 degrees C, whereas no inhibition was observed at the second warming cycle. When the organic load rate was increased to 6.37 g VS/L/d, the biogas yield of the STAD reached about 400 mL/g VS, nearly double that of the constant-temperature AD (CTAD). STAD promoted the proliferation of Methanosarcina (up to 57.32 %), while severely suppressed hydrogenophilic methanogens. However, when the temperature was shifted to 35 degrees C, most suppressed species recovered quickly and the excess propionic acid was quickly consumed. Metagenomic analysis showed that STAD also promoted gene enrichment related to pathways metabolism, membrane functions, and methyl-based methanogenesis.

Morel (Morchella sextelata), a fungus with considerable nutritional, medicinal, and economic value, has been extensively cultivated in China. In May 2023, a rot disease was observed on approximately 20% of the fruiting bodies in a morel greenhouse located in Harbin city, Heilongjiang province, China. In the present investigation, a total of fifteen fungal isolates were obtained, and subsequent analysis confirmed their identification as Penicillium raperi based on morphological and phylogenetic methods. Pathogenicity test provided evidence that P. raperi was capable of inducing rot symptoms which closely resembled those observed in field, thus confirming that P. raperi is the pathogen of M. sextelata. Thereby, this is the first report of P. raperi causing rot disease on M. sextelata worldwide. This study will furnish crucial insights for the management of diseases affecting morel mushrooms in the field.

Alternaria species are fungal pathogens that can infect maize, causing leaf blight disease and significant economic losses. This study aimed to determine the baseline sensitivity to prochloraz of A. alternata isolates obtained from diseased maize leaves collected from Heilongjiang province by assessing the half-maximal effective concentration (EC50) values. The EC50 values of prochloraz ranged from 0.0550 µg/mL to 2.3258 µg/mL, with an average of 0.9995 ± 0.5192 µg/mL. At EC50 (1.2495 µg/mL) and 2EC50 (2.4990 µg/mL), prochloraz increased the number of mycelial offshoots, disrupted the cell membrane integrity of conidia and mycelia, and resulted in a reduced ergosterol content in the mycelia. Prochloraz significantly affected the mycelial cell membrane permeability and increased the malondialdehyde (MDA) content and superoxide dismutase (SOD) activity. No cross-resistance was detected between prochloraz and other fungicides. These data demonstrate that prochloraz is a promising fungicide for managing maize leaf blight caused by A. alternata and provide novel insights into understanding the mechanism of prochloraz toxicity against A. alternata isolates.

A novel ligninase-producing and cellulose-degrading actinobacterium, designated strain NEAU-A12

Wheat root rot, caused by Bipolaris sorokiniana , is a significant and extensive soilborne disease. Streptomyces sp. NEAU-KT41 was isolated from healthy wheat root soil and possessed strong antifungal activity against B. sorokiniana . Findings from the pot test indicated that strain NEAU-KT41 (10 8 CFU/mL) and its 10 % cell-free culture filtrate had significant biocontrol efficiency against wheat root rot, with 66.67 % and 64.4 %, respectively, resulting in significant increases in biomass and chlorophyll content. For 10 8 CFU/mL spore suspension, the plant height increased by 167.52 %; root length by 141.64 %, fresh weight by 65 %, chlorophyll a by 13.43 %, and chlorophyll b by 51.02 % under disease stress. For the 10 % cell-free culture filtrate, the plant height increased by 21.93 %, root length by 17.92 %, dry weight by 29.35 %, chlorophyll a by 17.92 %, and chlorophyll b by 82.15 % under disease stress. Moreover, strain NEAU-KT41 could produce proteases, amylases, lipases, and ACC deaminase, and had the ability to decompose organic phosphorus and fix nitrogen. The cell-free culture filtrate affected B. sorokiniana in several manners, including increasing the cell membrane permeability, diminishing the soluble protein content in the mycelia, impeding conidia germination and germ tube extension, and affecting B. sorokiniana invasion of plants. Briefly, Streptomyces sp. NEAU-KT41 is a prospective biocontrol agent that can be used to manage root rot in wheat and has potential applications.

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Sugar transporters have significant contributions to regulate metabolic flux towards products and they are general potential targets for engineering of high-yield microbial cell factories. Streptomyces, well-known producers of natural product pharmaceuticals, contain an abundance of sugar transporters, while few of them are well characterized and applied. Here, we report a previously unidentified ATP-binding cassette (ABC) sugar transporter TP6568 found within a Streptomyces avermitilis transposon library, along with its key regulator GM006564. Subsequent in silico molecular docking and genetic experiments demonstrated that TP6568 possessed a broad substrate specificity. It could not only promote uptake of diverse monosaccharides and disaccharides, but also enhance the utilization of industrial carbon sources such as starch, sucrose, and dextrin. Constitutive overexpression of TP6568 resulted in decrease of residual total sugar by 36.16