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Food is a fundamental human right, and global food security is threatened by crop production. Plant growth regulators (PGRs) play an essential role in improving crop yield and quality, and this study reports on a novel PGR, termed guvermectin (GV), isolated from plant growth-promoting rhizobacteria, which can promote root and coleoptile growth, tillering, and early maturing in rice. GV is a nucleoside analogue like cytokinin (CK), but it was found that GV significantly promoted root and hypocotyl growth, which is different from the function of CK in

A novel protease-producing actinomycete, designated strain NEAU-ZS1T, was isolated from the root of Perilla frutescens (Linn.) Britt collected from Jiamusi, Heilongjiang, PR China. Comparative 16S rRNA gene sequencing showed that strain NEAU-ZS1T belonged to the genus Sphaerisporangium and was most closely related to ‘ Sphaerisporangium corydalis ’ NEAU-YHS15T (99.2%) and Sphaerisporangium cinnabarinum JCM 3291T (99.0%). Phylogenetic tree analysis revealed that strain NEAU-ZS1T formed a monophyletic clade with ‘ S. corydalis ’ NEAU-YHS15T. The genome size was 9.3 Mbp with a DNA G+C content of 70.3 mol%. Digital DNA–DNA hybridization, average nucleotide identity and average amino acid identity values between the genome sequence of strain NEAU-ZS1T and those of ‘ S. corydalis ’ NEAU-YHS15T (28.6, 83.9 and 79.1 %) and S. cinnabarinum JCM 3291T (18.5, 70.6 and 50.2 %) were below the recommended thresholds for species delineation. The strain formed spherical spore vesicles produced on the aerial hyphae. The cell wall contained meso-diaminopimelic acid and the whole-cell sugars were glucose and madurose. The polar lipids consisted of diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylinositol, an unidentified phospholipid and an unidentified glycolipid. The menaquinones were MK-9(H4), MK-9(H6) and MK-9(H2). The major fatty acids were iso-C16 : 0, C16 : 1 ω5c, 10-methy C17 : 0 and C17 : 1 ω7c. On the basis of the results of a polyphasic taxonomic study, it is concluded that strain NEAU-ZS1T represents a novel species of the genus Sphaerisporangium , for which the name Sphaerisporangium perillae sp. nov. is proposed. The type strain is NEAU-ZS1T (=CCTCC AA 2021019T= JCM 35655T).

A novel endophytic actinomycete, designated strain NEAU-365T, was isolated from the root of Quercus variabilis collected from Nanjing, Jiangsu, PR China. Comparative 16S rRNA gene sequencing showed that strain NEAU-365T belonged to the genus Mumia but clearly differs from the currently recognized species Mumia zhuanghuii Z350T (99.31 %), Mumia xiangluensis NEAU-KD1T (98.82 %) and Mumia flava MUSC 201T (97.78 %). Phylogenetic tree analysis revealed that strain NEAU-365T clustered with the type strains of the genus Mumia . The genome size was 4.1 Mbp with a DNA G+C content of 71.2 mol%. Digital DNA–DNA hybridization and average nucleotide identity values between the genome sequence of strain NEAU-365T and those of M. zhuanghuii Z350T(27.5 and 84.0 %), M. xiangluensis NEAU-KD1T(23.4 and 80.9 %) and M. flava MUSC 201T(20.9 and 77.7 %) were below the recommended thresholds for species delineation. Cells were observed to be irregular cocci shaped. The cell wall contained ll-diaminopimelic acid and the whole-cell sugars were galactose and rhamnose. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid and three unidentified phospholipids. The predominant menaquinone was detected as MK-9(H4). The major fatty acids were C16 : 0, C18 : 0, C18 : 1 ω9c and 10-methyl C18 : 0. On the basis of genotypic and phenotypic differences from members of the genus Mumia , a novel species, Mumia quercus sp. nov. is proposed. The type strain is NEAU-365T (=CCTCC AA 2021033T=JCM 35005T).

Flowering is a crucial stage for plant reproductive success; therefore, the regulation of plant flowering has been widely researched. Although multiple well-defined endogenous and exogenous flowering regulators have been reported, new ones are constantly being discovered. Here, we confirm that a novel plant growth regulator guvermectin (GV) induces early flowering in Arabidopsis. Interestingly, our genetic experiments newly demonstrated that WRKY41 and its homolog WRKY53 were involved in GV-accelerated flowering as positive flowering regulators. Overexpression of WRKY41 or WRKY53 resulted in an early flowering phenotype compared to the wild type (WT). In contrast, the w41/w53 double mutants showed a delay in GV-accelerated flowering. Gene expression analysis showed that flowering regulatory genes SOC1 and LFY were upregulated in GV-treated WT, 35S:WRKY41, and 35S:WRKY53 plants, but both declined in w41/w53 mutants with or without GV treatment. Meanwhile, biochemical assays confirmed that SOC1 and LFY were both direct targets of WRKY41 and WRKY53. Furthermore, the early flowering phenotype of 35S:WRKY41 lines was abolished in the soc1 or lfy background. Together, our results suggest that GV plays a function in promoting flowering, which was co-mediated by WRKY41 and WRKY53 acting as new flowering regulators by directly activating the transcription of SOC1 and LFY in Arabidopsis.

A novel endophytic actinomycete with antagonistic activity against various phytopathogenic fungi, designated strain p1417T, was isolated from the root of cattail (Typha angustifolia L.) collected from Yunnan Province, Southwest China. A polyphasic taxonomic study was carried out to establish the taxonomic status of this strain. Strain p1417T was found to have morphological and chemotaxonomic characteristics typical of the genus Streptomyces. The diamino acid present in the cell wall was LL-diaminopimelic acid. Xylose and arabinose occurred in whole cell hydrolysates. The menaquinones were identified as MK-9(H8), MK-9(H6) and MK-9(H4). The polar lipid profile was found to contain diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The major fatty acids were found to be iso-C16:0, anteiso-C15:0, iso-C15:0 and C16:0. The genomic DNA G + C content of strain p1417T based on the genome sequence was 72.0 mol%. Based on 16 S rRNA gene, five housekeeping genes and whole genome sequences analysis, strain p1417T was most closely related to Streptomyces flavofungini JCM 4753T (99.4% 16 S rRNA gene sequence similarity), Streptomyces alboflavus JCM 4615T (98.8%) and Streptomyces aureoverticillatus JCM 4347T (98.2%). However, the average nucleotide identity values, the digital DNA–DNA hybridization values and the multilocus sequence analysis evolutionary distances between this strain and its closely related strains showed that it belonged to one distinct species. In addition, these results were also supported by differences in the phenotypic and chemotaxonomic characteristics between strain p1417T and three closely related type strains. Therefore, it is concluded that strain p1417T represents a novel species of the genus of Streptomyces, for which the name Streptomyces typhae sp. nov. is proposed. The type strain is p1417T (= CCTCC AA 2019091T = DSM 110636T).

In this study, the supernatant extract from fermentation broth of Streptomyces sp. NEAU-H3 showed strong antifungal activity against Fusarium graminearum strain PH-1 in vitro and in vivo. Three known pyranonaphthoquinones were isolated by means of an activity-guided method, and frenolicin B was characterized as the main active ingredient. Frenolicin B displayed strong antifungal activity against F. graminearum strain PH-1 with an EC50 value of 0.51 mg/L, which is lower than that of carbendazim (0.78 mg/L) but higher than that of phenamacril (0.18 mg/L). Frenolicin B could also strongly inhibit the mycelial growth of Fusarium species, including F. graminearum and F. asiaticum, as well as carbendazim-resistant Fusarium strains isolated from field, with EC50 values of 0.25-0.92 mg/L. Results from field experiments showed that the efficacy of frenolicin B in controlling Fusarium head blight at a treatment concentration of 75 g ai/ha was better than those of phenamacril (375 g ai/ha) and carbendazim (600 g ai/ha) or had no significant difference with that of phenamacril (375 g ai/ha) in 2 years. Scanning electron microscope and transmission electron microscope observations revealed that after treating F. graminearum mycelia with frenolicin B, the mycelia appeared aberrant and had an uneven thickness and swelling, the cytoplasm had disintegrated, and some cell contents were lost. Transcriptome analysis suggests that frenolicin B might inhibit the metabolism of nucleotides and energy by affecting genes involved in phosphorus utilization but did not affect the expression of myosin 5, which is the specific target of phenamacril. These findings indicate that frenolicin B may be a potential agrochemical fungicide for controlling Fusarium head blight.

A novel endophytic actinomycete, designated strain p1410T, was isolated from the root of cattail pollen (Typha angustifolia L.) and characterized using a polyphasic approach. The strain had morphological characteristics and chemotaxonomic properties identical to those of members of the genus Nonomuraea . It produced spiral chains of spores on aerial mycelium as well as forming a pseudosporangium. Whole-cell hydrolysates contained meso-diaminopimelic acid, glucose, ribose and madurose. The menaquinones detected were MK-9(H2), MK-9(H4) and MK-9(H0). The major fatty acids were 10-methyl C17 : 0, iso-C16 : 0 and C17 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylinositol mannoside and an unknown glycolipid. The DNA G+C content of the draft genome sequence, consisting of 11.4 Mbp, was 70.9 mol%. Phylogenetic analysis of 16S rRNA gene sequences showed that strain p1410T belongs to the genus Nonomuraea with the highest sequence similarity to Nonomuraea candida HMC10T (98.6 %), but phylogenetically clustered with Nonomuraea endophytica YIM 65601T (98.4 %) and Nonomuraea longicatena NRRL 15532T (98.3 %). Based on its phenotypic characteristics, DNA–DNA relatedness and average nucleotide identity, the strain is considered to represent a novel species of the genus Nonomuraea , for which the name Nonomuraea typhae sp. nov. is proposed. The type strain is p1410T (=CCTCC AA 2019044T=JCM 33461T).

Chemical investigation of a soil actinomycete strain Streptomyces gamaensis NEAU-Gz11 led to the isolation of three alkaloids 1–3 with antiviral activity. Their structures were determined by extensive spectroscopic and X-ray crystallographic analyses. Compound 1 possesses a new and unique spiro-β-triazinedione-γ-hydantoin skeleton. The racemic feature and the chemical conversion experiments led us to propose a biosynthetic pathway for 1. Compound 1 (100 mg L−1) showed a strong anti-TMV (tobacco mosaic virus, TMV) activity on the host plants of tomatoes and peppers with inhibition rates of 72.34% and 62.09%, respectively.

Six new pimprinine alkaloids (1–6), including four dimers, dipimprinines A–D (1–4), and two monomers, (±)-Pimprinol D (5), and pimprinone A (6), along with six known congeners (7–12), were isolated from a soil-derived actinomycete Streptomyces sp. NEAU-C99. Structures of the new compounds were elucidated by extensive spectroscopic analyses, single-crystal X-ray diffractions, and ECD calculations. Dipimprinines A–D (1–4) showed weak cytotoxic activities against five tumor cell lines, including HL-60, SMMC-7721, A-549, MCF-7, and SW-480, with IC50 values ranging from 12.7 to 30.7 μM.

The rhizosphere, an important battleground between beneficial microbes and pathogens, is usually considered to be a good source for isolation of antagonistic microorganisms. In this study, a novel actinobacteria with broad-spectrum antifungal activity, designated strain NEAU-H2T, was isolated from the rhizosphere soil of wheat (Triticum aestivum L.). 16S rRNA gene sequence similarity studies showed that strain NEAU-H2T belonged to the genus Streptomyces, with high sequence similarities to Streptomyces rhizosphaerihabitans NBRC 109807T (98.8%), Streptomyces populi A249T (98.6%), and Streptomyces siamensis NBRC 108799T (98.6%). Phylogenetic analysis based on 16S rRNA, atpD, gyrB, recA, rpoB, and trpB gene sequences showed that the strain formed a stable clade with S. populi A249T. Morphological and chemotaxonomic characteristics of the strain coincided with members of the genus Streptomyces. A combination of DNA&ndash, DNA hybridization results and phenotypic properties indicated that the strain could be distinguished from the abovementioned strains. Thus, strain NEAU-H2T belongs to a novel species in the genus Streptomyces, for which the name Streptomyces triticiradicis sp. nov. is proposed. In addition, the metabolites isolated from cultures of strain NEAU-H2T were characterized by nuclear magnetic resonance (NMR) and mass spectrometry (MS) analyses. One new compound and three known congeners were isolated. Further, genome analysis revealed that the strain harbored diverse biosynthetic potential, and one cluster showing 63% similarity to natamycin biosynthetic gene cluster may contribute to the antifungal activity. The type strain is NEAU-H2T (= CCTCC AA 2018031T = DSM 5775T).

A novel actinobacterium, designated strain NEAU-QY24T, was isolated from the rhizosphere of corn (Zea mays L.). A polyphasic approach was employed to determine the taxonomic status of strain NEAU-QY24T. The isolate was found to have chemical and morphological properties of the genus Streptomyces, with high 16S rRNA gene sequence similarity to Streptomyces lanatus JCM 4332T (98.3%) and clustered phylogenetically with Streptomyces lannensis JCM 16578T (98.2%). The cell wall was found to contain meso-diaminopimelic acid and the whole cell sugars were identified as glucose and ribose. The predominant menaquinones were identified as MK-9(H6), MK-9(H4) and MK-9(H8). The phospholipid profile was found to consisted of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol. The major fatty acids were identified as iso-C16:0, C16:0, anteiso-C17:0 and C15:0. A combination of DNA–DNA hybridization experiments and phenotypic tests were carried out between strain NEAU-QY24T and its closely related strains, which clarified their relatedness and demonstrated that strain NEAU-QY24T could be distinguished from these strains. These data indicate that the isolate should be recognised as a new species of the genus Streptomyces, for which the name Streptomyces flavalbus sp. nov. is proposed. The type strain is NEAU-QY24T (= CGMCC 4.7400T = DSM 104539T).

A novel actinomycete, designated strain 1H-SSA4T, was isolated from the head of an ant (Camponotus japonicus Mayr) and was found to produce angucyclinone antibiotics. A polyphasic approach was used to determine the taxonomic status of strain 1H-SSA4T. The DNA G+C content of the draft genome sequence, consisting of 11.4 Mbp, was 70.0 mol%. 16S rRNA gene sequence similarity studies showed that strain 1H-SSA4T belongs to the genus Streptomyces with the highest sequence similarity to Streptomyces hygroscopicus subsp. ossamyceticus NBRC 13983T (98.9 %), and phylogenetically clustered with this species, Streptomyces torulosus LMG 20305T (98.8 %), Streptomyces ipomoeae NBRC 13050T (98.5 %) and Streptomyces decoyicus NRRL 2666T (98.4 %). The morphological and chemotaxonomic properties of the strain were also consistent with those members of the genus Streptomyces . A combination of DNA–DNA hybridization experiments and phenotypic tests were carried out between strain 1H-SSA4T and the above-mentioned strains, which further clarified their relatedness and demonstrated that strain 1H-SSA4T could be distinguished from these strains. Therefore, the strain is concluded to represent a novel species of the genus Streptomyces , for which the name Streptomyces capitiformicae sp. nov. is proposed. The type strain is 1H-SSA4T (=CGMCC 4.7403T=DSM 104537T).

A novel actinomycete strain, designated NEAU-C2T, was isolated from rhizosphere soil of wheat (Triticum aestivum L.), and subjected to a polyphasic taxonomic study. Morphological and chemotaxonomic properties of this strain were consistent with the description of the genus Glycomyces. Growth was found to occur at a temperature range of 15–40 °C, pH 6–10 and NaCl concentrations of 0–4%. The cell wall was found to contain meso-diaminopimelic acid and the whole cell sugars were identified as galactose, xylose and ribose. The predominant menaquinones were identified as MK-10(H6) and MK-10(H2). The polar lipids were found to consist of diphosphatidylglycerol, phosphatidylinositol, phosphatidylglycerol, phosphoglycolipids and an unidentified glycolipid. The major fatty acids were identified as anteiso-C15:0, iso-C16:0, anteiso-C17:0 and iso-C15:0. 16S rRNA gene sequence similarity studies showed that strain NEAU-C2T belongs to the genus Glycomyces with high sequence similarity to Glycomyces algeriensis NRRL B-16327T (99.0% sequence similarity). Some physiological and biochemical properties and low DNA–DNA relatedness values enabled the strain to be differentiated from closely related species of the genus Glycomyces. It is concluded that the isolate can be classified as representing a novel species of the genus Glycomyces, for which the name Glycomyces tritici is proposed. The type strain is NEAU-C2T (= DSM 104644T = CGMCC 4.7410T).

A novel actinomycete, designated strain 1H-SSA8T, was isolated from the head of an ant (Camponotus japonicus Mayr) and was found to produce amphotericin. A polyphasic approach was employed to determine the status of strain 1H-SSA8T. Morphological and chemotaxonomic characteristics were consistent with those of members of the genus Streptomyces . The menaquinones detected were MK-9(H6), MK-9(H8) and MK-9(H4). The phospholipid profile consisted of diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine and phosphatidylinositol mannoside. The major fatty acids were identified as iso-C16 : 0, C16 : 0, C15 : 0 and anteiso-C15 : 0. Analysis of the 16S rRNA gene sequence showed that strain 1H-SSA8T belongs to the genus Streptomyces with high sequence similarity to Streptomyces ramulosus NRRL B-2714T (99.2 %). Two tree-making algorithms based on 16S rRNA gene sequences showed that the isolate formed a phyletic line with Streptomyces himastatinicus ATCC 53653T (98.7 %). The MLSA utilizing partial sequences of the housekeeping genes (atpD, gyrB, recA, rpoB and trpB) also supported the position. However, evolutionary distances were higher than the 0.007 MLSA evolutionary distance threshold proposed for species-level relatedness. Moreover, the low level of DNA–DNA relatedness and phenotypic differences allowed the novel isolate to be differentiated from its most closely related strain S. ramulosus NRRL B-2714T and strain S. himastatinicus ATCC 53653T. It is concluded that the organism can be classified as representing a novel species of the genus Streptomyces , for which the name Streptomyces amphotericinicus sp. nov. is proposed. The type strain is 1H-SSA8T (=CGMCC 4.7350T=DSM 103128T).

During a screening for novel and biotechnologically useful actinobacteria in insects, a novel actinobacteria with antifungal activity, designated strain 5H-CA11T, was isolated from the head of an ant (Lasius flavus) and characterized using a polyphasic approach. The organism was found to have morphological and chemotaxonomic characteristics typical of members of the genus Streptomyces. 16S rRNA gene sequence analysis showed that strain 5H-CA11T is a member of the genus Streptomyces, with the highest sequence similarity to Streptomyces scabrisporus DSM 41855T (98.9%). Similarities to other type strains of the genus Streptomyces were lower than 96%. Phylogenetic analysis based on the 16S rRNA gene sequence also indicated that strain 5H-CA11T clusters with S. scabrisporus DSM 41855T using two tree-making algorithms. DNA-DNA hybridization between strain 5H-CA11T and S. scabrisporus JCM 11712T revealed 33.6% similarity, supporting the phenotypic and phylogenetic differences found between these two strains. Therefore, the strain is concluded to represent a novel species of the genus Streptomyces, for which the name Streptomyces lasii sp. nov. is proposed. The type strain is 5H-CA11T (=CGMCC 4.7303T = DSM 102043T).

Two Gram-stain-positive, aerobic actinomycete strains, designated NEAU-PCY-3T and NEAU-PCY-4, were isolated from rhizosphere soil of Urtica urens L. collected from Anshan, Liaoning Province, northeast PR China. The 16S rRNA gene sequence analysis showed that the two strains exhibited 99.9 % 16S rRNA gene sequence similarity with each other and that they were most closely to Longispora fulva DSM 45356T (98.7, 98.9 %) and Longispora albida JCM 11711T (97.1, 97.2 %). Phylogenetic analysis based on the 16S rRNA gene sequences indicated that the two strains were located in the same lineage and formed a cluster with the genus Longispora. Both strains were observed to contain MK-10(H4) and MK-10(H6) as the predominant menaquinones. The cell wall peptidoglycan was found to contain meso-diaminopimelic acid, d-glutamic acid, glycine and l-alanine. Whole-cell hydrolysates mainly contained galactose, ribose and xylose. The phospholipid profile contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, several glycolipids and several unknown lipids. The major cellular fatty acids for strain NEAU-PCY-3T were iso-C16 : 0, iso-C17 : 0, anteiso-C17 : 0 and C18 : 1ω5c. The DNA-DNA hybridization value between strains NEAU-PCY-3T and NEAU-PCY-4 was 83.6±0.4 %, and the values between the two strains and their closest phylogenetic relatives, belonging to the genus Longispora, were well below 70 %, supporting that they represented a distinct genomic species. An array of phenotypic characteristics also differentiated the strains from their closely related species, the only two validly published Longispora species. On the basis of the genetic, chemotaxonomic and phenotypic properties, strains NEAU-PCY-3T and NEAU-PCY-4 were classified as representatives of a novel species of the genus Longispora, for which the name Longispora urticae sp. nov. is proposed. The type strain is NEAU-PCY-3T (=DSM 105119T=CCTCC AA 2017017T).

A novel actinobacterium, designated strain NEAU-GS50T, was isolated from soil collected from Mount Song and characterized by using a polyphasic approach. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the organism should be assigned to the genus Promicromonospora and that it forms a monophyletic clade with its closest relatives Promicromonospora umidemergens JCM 17975T (98.94 % 16S rRNA gene sequence similarity), Promicromonospora alba 1C-HV12T (98.82 %) and Promicromonospora kermanensis DSM45485T (98.68 %). Similarly, chemotaxonomic data including major menaquinones, fatty acid compositions and polar lipid profiles, also supported the placement of strain NEAU-GS50T in the genus Promicromonospora . However, DNA–DNA relatedness, physiological and biochemical data showed that strain NEAU-GS50T could be distinguished from its closest relatives. Therefore, strain NEAU-GS50T represents a novel species of the genus Promicromonospora , for which the name Promicromonospora soli sp. nov. is proposed, with strain NEAU-GS50T (CGMCC4.7398T=DSM 104515T) as the type strain.

The supporting informations for the article "Taxonomic Characterization and Secondary Metabolite Analysis of Streptomyces triticiradicis sp. nov., a Novel Actinomycete with Antifungal Activity"

A novel endophytic actinomycete, designated strain LD22T, was isolated from moss [Physcomitrium sphaericum (Ludw) Fuernr] collected from Yunnan Province, Southwest China. A polyphasic taxonomic study was carried out to establish the status of this strain. Morphological and chemotaxonomic characteristics of strain LD22T confirmed the affiliation of the isolate to the genus Actinomadura. The diamino acid present in the cell wall is meso-diaminopimelic acid. Glucose, madurose, galactose and ribose occur in whole cell hydrolysates. The menaquinones were identified as MK-9(H4), MK-9(H8), MK-9(H6) and MK-9(H2). The polar lipid profile was found to contain diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified phospholipid. The major fatty acids were found to be C16:0, 10-methyl C18:0 and C18:1 ω9c. The DNA G + C content of the draft genome sequence, consisting of 10.0 Mbp, was 72.5%. Phylogenetic analysis of 16S rRNA gene sequences showed that strain LD22T belongs to the genus Actinomadura with the highest sequence similarity to Actinomadura montaniterrae CYP1-1BT (99.2%). However, phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate formed a phyletic line with Actinomadura rudentiformis HMC1T (98.6%). The low level of DNA–DNA relatedness and some different phenotypic characteristics allowed the strain to be distinguished from the above-mentioned two strains. Therefore, it is concluded that strain that strain LD22T represents a novel species of the genus of Actinomadura, for which the name Actinomadura physcomitrii sp. nov. is proposed. The type strain is LD22T (= CCTCC AA 2018050T = JCM 33455T).

The present study was conducted to examine the influence of a pathogen Sclerotinia sclerotiorum (Lib.) de Bary on the actinobacterial community associated with the soybean roots. A total of 70 endophytic actinobacteria were isolated from the surface-sterilized roots of either healthy or diseased soybeans, and they were distributed under 14 genera. Some rare genera, including Rhodococcus, Kribbella, Glycomyces, Saccharothrix, Streptosporangium and Cellulosimicrobium, were endemic to the diseased samples, and the actinobacterial community was more diverse in the diseased samples compared with that in the heathy samples. Culture-independent analysis of root-associated actinobacterial community using the high-throughput sequencing approach also showed similar results. Four Streptomyces strains that were significantly abundant in the diseased samples exhibited strong antagonistic activity with the inhibition percentage of 54.1&ndash, 87.6%. A bioactivity-guided approach was then employed to isolate and determine the chemical identity of antifungal constituents derived from the four strains. One new maremycin analogue, together with eight known compounds, were detected. All compounds showed significantly antifungal activity against S. sclerotiorum with the 50% inhibition (EC50) values of 49.14&ndash, 0.21 mg/L. The higher actinobacterial diversity and more antifungal strains associated with roots of diseased plants indicate a possible role of the root-associated actinobacteria in natural defense against phytopathogens. Furthermore, these results also suggest that the root of diseased plant may be a potential reservoir of actinobacteria producing new agroactive compounds.

Figure S1. 1H NMR and 13C NMR (600 MHz) spectra of compounds 1-8;Figure S2. 1H NMR,13C NMR,1H-1H COSY,HSQC,HMBC,Roesy,Optical rotation, CD,UV,IR andHRESIspectra of compound 9.

During an investigation exploring potential sources of novel species and natural products, a novel actinomycete with antifungal activity, designated strain NEAU-Gz11T, was isolated from a soil sample, which was collected from Gama, Chad. The isolate was found to have morphological and chemotaxonomic characteristics typical of members of the genus Streptomyces. 16S rRNA gene sequence similarity studies showed that strain NEAU-Gz11T belongs to the genus Streptomyces with high sequence similarity to Streptomyces hiroshimensis JCM 4098T (98.0 %). Similarities to other type strains of the genus Streptomyces were lower than 98.0 %. However, the physiological and biochemical characteristics and low levels of DNA–DNA relatedness could differentiate the isolate genotypically and phenotypically from S. hiroshimensis JCM 4098T. Therefore, the strain is concluded to represent a novel species of the genus Streptomyces, for which the name Streptomyces gamaensis sp. nov. is proposed. The type strain is NEAU-Gz11T (=CGMCC 4.7304T=DSM 101531T).

A novel actinobacterium, designated strain NEAU-QY3T, was isolated from the leaves of Sonchus oleraceus L. and examined using a polyphasic taxonomic approach. The organism formed single spores with smooth surface on substrate mycelia. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the strain had a close association with the genus Verrucosispora and shared the highest sequence similarity with Verrucosispora qiuiae RtIII47T (99.17 %), an association that was supported by a bootstrap value of 94 % in the neighbour-joining tree and also recovered with the maximum-likelihood algorithm. The strain also showed high 16S rRNA gene sequence similarities to Xiangella phaseoli NEAU-J5T (98.78 %), Jishengella endophytica 202201T (98.51 %), Micromonospora eburnea LK2-10T (98.28 %), Verrucosispora lutea YIM 013T (98.23 %) and Salinispora pacifica CNR-114T (98.23 %). Furthermore, phylogenetic analysis based on the gyrB gene sequences supported the conclusion that strain NEAU-QY3T should be assigned to the genus Verrucosispora . However, the DNA–DNA hybridization relatedness values between strain NEAU-QY3T and V. qiuiae RtIII47T and V. lutea YIM 013T were below 70 %. With reference to phenotypic characteristics, phylogenetic data and DNA–DNA hybridization results, strain NEAU-QY3T was readily distinguished from its most closely related strains and classified as a new species, for which the name Verrucosispora sonchi sp. nov. is proposed. The type strain is NEAU-QY3T (=CGMCC 4.7312T=DSM 101530T).

A new spectinabilin derivative (1) was isolated from the fermentation broth of the ant-derived Streptomyces sp. 1H-GS5, and the structure was elucidated by extensive spectroscopic analysis. Compound 1 showed cytotoxicity against human tumor cell lines A549, HCT-116, and HepG2 with IC

A novel actinomycete, designated strain 3C-HV12T, was isolated from the cuticle of an ant (Lasius fuliginosus L) and characterised using a polyphasic approach. 16S rRNA gene sequence similarity studies showed that strain 3C-HV12T belongs to the genus Nocardia with high sequence similarities to Nocardia soli DSM 44488T (99.2 %) and Nocardia cummidelens R89T (99.2 %), and phylogenetically clustered with these two species and Nocardia ignorata DSM 44496T (98.8 %), Nocardia salmonicida JCM 4826T (98.8 %), Nocardia fluminea S1T (98.8 %), Nocardia coubleae OFN N12T (98 %) and Nocardia camponoti 1H-HV4T (97.4 %). The morphological and chemotaxonomic properties of the strain are also consistent with those of members of the genus Nocardia. The strain was observed to form extensively branched substrate hyphae which fragmented into rod-shaped and non-motile elements. The cell wall was found to contain meso-diaminopimelic acid and the whole cell sugars were identified as arabinose and galactose. The predominant menaquinone was identified as MK-8(H4, ω-cycl). The phospholipid profile was found to consist of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The major fatty acids were identified as C18:0 10-methyl, C16:0 and C16:1ω7c. Mycolic acids were found to be present. A combination of DNA–DNA hybridisation experiments and phenotypic tests were carried out between strain 3C-HV12T and its phylogenetically closely related strains, which further clarified their relatedness and demonstrated that 3C-HV12T could be distinguished from these strains. Therefore, the strain is concluded to represent a novel species of the genus Nocardia, for which the name Nocardia lasii sp. nov. is proposed. The type strain is 3C-HV12T (=DSM 100525T = CGMCC 4.7279T).

A Gram-positive, aerobic, motile, rod-shaped bacterium, designated strain C9(T), was isolated from surface sterilised corn roots (Zea mays cv. Xinken-5) and found to be able to produce indole-3-acetic acid. A polyphasic taxonomic study was carried out to determine the status of strain C9(T). The major cellular fatty acids were found to contain iso-C15:0, anteiso-C15:0 and anteiso-C17:0, and the only menaquinone was identified as MK-7. The polar lipid profile was found to contain diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and an unidentified lipid. The cell wall peptidoglycan was found to be of the A4α L-Lys-D-Asp type and the whole cell sugar was found to be glucose. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain C9(T) belongs to the genus Lysinibacillus and is closely related to Lysinibacillus chungkukjangi NBRC 108948(T) (98.1 % similarity) and Lysinibacillus sinduriensis DSM 27595(T) (98.0 %). However, the low levels of DNA-DNA relatedness and some differential phenotypic characteristics allowed the strain to be distinguished from its close relatives. Therefore, it is concluded that strain C9(T) represents a novel species of the genus Lysinibacillus, for which the name Lysinibacillus endophyticus sp. nov. is proposed. The type strain is C9(T) (=DSM 100506(T) = CGMCC 1.15291(T)).

A novel actinomycete, designated strain NEAU-gxj3T, was isolated from soybean root [Glycine max (L.) Merr.] collected from Harbin, Heilongjiang Province, China, and characterized using a polyphasic approach. The 16S rRNA gene sequence of strain NEAU-gxj3T showed highest similarity to those of Micromonospora equina Y22T (98.2 %) and Plantactinospora endophytica YIM 68255T (98.0 %). Phylogenetic analysis based on the 16S rRNA gene and gyrB gene demonstrated that the isolate clustered with the members of the genus Plantactinospora. The chemotaxonomic properties of strain NEAU-gxj3Twere also consistent with those of members of the genus Plantactinospora. The cell wall contained meso-diaminopimelic acid and whole-cell sugars were xylose, glucose and galactose. The predominant menaquinones were MK-10(H6), MK-9(H8), MK-10(H2) and MK-10(H4). The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The major fatty acids were identified as anteiso-C17 : 0, iso-C16 : 0, iso-C15 : 0 and C15 : 0. A combination of DNA-DNA hybridization result and some phenotypic characteristics indicated that strain NEAU-gxj3Tcould be differentiated clearly from its closest phylogenetic relatives. Therefore, the strain is concluded to represent a novel species of the genus Plantactinospora, for which the name Plantactinospora soyae sp. nov. is proposed. The type strain is NEAU-gxj3T (=CGMCC 4.7221T=DSM 46832T).

A novel actinobacterium, designated strain NEAU-ND5T, was isolated from the rhizosphere of corn (Zea mays L.) collected in Heilongjiang Province, north-east China, and characterized using a polyphasic approach. 16S rRNA gene sequence analysis showed that strain NEAU-ND5T was a member of the genus Nonomuraea, with highest sequence similarities to Nonomuraea jabiensis A4036T (98.29 %), Nonomuraea rosea GW12687T (98.25 %), Nonomuraea candida HMC10T (98.22 %), Nonomuraea rhizophila YIM 67092T (98.04 %) and Nonomuraea kuesteri NRRL B-24325T (98.04 %). Similarities to other type strains of the genus Nonomuraea were lower than 98 %. Morphological and chemotaxonomic properties of strain NEAU-ND5T were also consistent with the description of the genus Nonomuraea. The cell wall contained meso-diaminopimelic acid and the whole-cell sugars were glucose, ribose and madurose. The phospholipid profile consisted of diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, hydroxy-phosphatidylmonomethylethanolamine, hydroxy-phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The major menaquinones were MK-9(H4), MK-9(H2) and MK-9(H0). The predominant cellular fatty acids were iso-C16:0 and 10-methyl C17:0. A combination of DNA-DNA hybridization results and some phenotypic characteristics demonstrated that strain NEAU-ND5T was clearly distinguished from its closely related Nonomuraea species. Consequently, it is concluded that strain NEAU-ND5T represents a novel species of the genus Nonomuraea, for which the name Nonomuraea zeae sp. nov. is proposed. The type strain is NEAU-ND5T (=CGMCC 4.7280T=DSM 100528T).

Two novel actinobacteria, designated strains NEAU-Jh1-4T and NEAU-Wp2-0T, were isolated from muddy soil collected from a riverbank in Jiaohe and a dandelion root collected from Harbin, respectively. A polyphasic study was carried out to establish the taxonomic positions of these two strains. The phylogenetic analysis based on the 16S rRNA gene sequences of strains NEAU-Jh1-4T and NEAU-Wp2-0T indicated that strain NEAU-Jh1-4T clustered with Streptosporangium nanhuense NEAU-NH11T (99.32 % 16S rRNA gene sequence similarity), Streptosporangium purpuratum CY-15110T (98.30 %) and Streptosporangium yunnanense CY-11007T (97.95 %) and strain NEAU-Wp2-0T clustered with ‘ Streptosporangium sonchi ’ NEAU-QS7 (99.39 %), ‘ Streptosporangium kronopolitis ’ NEAU-ML10 (99.26 %), ‘ Streptosporangium shengliense ’ NEAU-GH7 (98.85 %) and Streptosporangium longisporum DSM 43180T (98.69 %). Moreover, morphological and chemotaxonomic properties of the two isolates also confirmed their affiliation to the genus Streptosporangium . However, the low level of DNA–DNA hybridization and some phenotypic characteristics allowed the isolates to be differentiated from the most closely related species. Therefore, it is proposed that strains NEAU-Jh1-4T and NEAU-Wp2-0T represent two novel species of the genus Streptosporangium , for which the name Streptosporangium jiaoheense sp. nov. and Streptosporangium taraxaci sp. nov. are proposed. The type strains are NEAU-Jh1-4T (=CGMCC 4.7213T=JCM 30348T) and NEAU-Wp2-0T (=CGMCC 4.7217T=JCM 30349T), respectively.

A novel endophytic actinomycete, designated strain NEAU-HZ10(T) was isolated from moss and characterised using a polyphasic approach. The strain was found to have morphological and chemotaxonomic characteristics typical of the genus Streptomyces. Strain NEAU-HZ10(T) formed grayish aerial mycelia, which differentiated into straight to flexuous chains of cylindrical spores. The cell wall peptidoglycan was found to contain LL-diaminopimelic acid. Predominant menaquinones were identified as MK-9(H6) and MK-9(H8). The polar lipid profile was found to consist of phosphatidylethanolamine, phosphatidylinositol and two unidentified phospholipids. The major fatty acids were identified as iso-C16:0, anteiso-C15:0 and C16:0. 16S rRNA gene sequence similarity studies showed that strain NEAU-HZ10(T) belongs to the genus Streptomyces and exhibits high sequence similarity to Streptomyces cocklensis DSM 42063(T) (98.9 %). Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain NEAU-HZ10(T) clustered with S. cocklensis DSM 42063(T), Streptomyces yeochonensis CGMCC 4.1882(T) (98.7 %), Streptomyces paucisporeus CGMCC 4.2025(T) (98.4 %) and Streptomyces yanglinensis CGMCC 4.2023(T) (98.1 %). However, a combination of DNA-DNA hybridisation results and some phenotypic characteristics indicated that strain NEAU-HZ10(T) can be distinguished from its phylogenetically closely related strains. Therefore, it is proposed that strain NEAU-HZ10(T) represents a novel species of the genus Streptomyces for which the name Streptomyces bryophytorum sp. nov. is proposed. The type strain is NEAU-HZ10(T) (= CGMCC 4.7151(T) = DSM 42138(T)).

A novel actinobacterium, designated strain NEAU-FJL2(T), was isolated from a tomato root (Solanum lycopersicum L.) and characterised using a polyphasic approach. Morphological and chemotaxonomic properties of strain NEAU-FJL2(T) are consistent with the description of the genus Dactylosporangium. Finger-shaped sporangia were observed to form on short sporangiophores branching from the substrate hyphae. The cell wall peptidoglycan was found to contain meso- and 3-hydroxy-diaminopimelic acids; arabinose, mannose, rhamnose and xylose were found as whole-cell sugars. The phospholipid profile was found to consist of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol. The predominant menaquinones were identified as MK-9(H8) and MK-9(H6). The major fatty acids were identified as iso-C16:0, C16:1 ω7c and iso-C15:0. Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that strain NEAU-FJL2(T) belongs to the genus Dactylosporangium, with Dactylosporangium sucinum JCM 19831(T) (99.3 % 16S rRNA gene sequence similarity), Dactylosporangium darangshiense JCM 17441(T) (99.2 %), Dactylosporangium fulvum JCM 5631(T) (98.9 %) and Dactylosporangium roseum JCM 3364(T) (98.8 %) as the nearest phylogenetic relatives. However, a combination of DNA-DNA hybridization results and some phenotypic characteristics demonstrated that strain NEAU-FJL2(T) can be distinguished from them. Consequently, it is proposed that strain NEAU-FJL2(T) represents a novel species of the genus Dactylosporangium, for which the name Dactylosporangium solaniradicis sp. nov. is proposed. The type strain is NEAU-FJL2(T) (=CGMCC 4.7302(T) = DSM 100814(T)).

During an investigation of microbial diversity in medicinal herbs, a novel actinobacterium, strain NEAU-KD1(T) was isolated from the rhizosphere of Peucedanum praeruptorum Dunn collected from Xianglu Mountain in Heilongjiang Province, northeast China and characterized using a polyphasic approach. The organism was found to have the typical chemotaxonomic and morphological characteristics of the genus Mumia. Cells were observed to be non-spore-forming and irregular cocci. The cell wall was found to contain LL-diaminopimelic acid as the cell wall diamino acid. The whole-cell sugars were detected as galactose and rhamnose and the predominant menaquinone was identified as MK-9(H4). The polar lipids were found to consist of diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid and five unidentified phospholipids. The major cellular fatty acids were determined to be composed of C16:0, 10-methyl C18:0 and C18:1ω7c. The phylogenetic analysis based on 16S rRNA gene sequence also indicated that strain NEAU-KD1(T) belongs to the genus Mumia and with high sequence similarity to Mumia flava NBRC 109973(T) (97.6 % sequence similarity). The results of DNA-DNA hybridization and the phenotypic characteristics indicated that strain NEAU-KD1(T) could be distinguished from its close phylogenetic relative. Thus, strain NEAU-KD1(T) can be concluded to represent a novel species of the genus Mumia, for which the name Mumia xiangluensis sp. nov. is proposed. The type strain is NEAU-KD1(T) (=CGMCC 4.7305(T) = DSM 101040(T)).

A novel actinomycete, designated strain NEAU-G9T, was isolated from the root of Polygonatum odoratum (Mill.) collected from Harbin, Heilongjiang province, north China, and was characterized using a polyphasic approach. Key morphological and chemotaxonomic properties confirmed the affiliation of strain NEAU-G9T to the genus Streptomyces. Strain NEAU-G9T contained ll-diaminopimelic acid as the diamino acid. The predominant menaquinones were MK-9(H8), MK-9(H6) and MK-9(H4). The phospholipid profile contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The predominant fatty acids were iso-C16 : 0, anteiso-C15 : 0 and C16 : 0.16S rRNA gene sequence similarity studies showed that strain NEAU-G9T belongs to the genus Streptomyces and exhibits the highest sequence similarity to Streptomyces yanglinensis JCM 13275T (97.75 %). However, phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain NEAU-G9T is most closely related to Streptomyces misakiensis JCM 4062T (97.12 % sequence similarity). A combination of DNA–DNA hybridization results and some phenotypic characteristics indicated that strain NEAU-G9T can be clearly distinguished from S. yanglinensis JCM 13275T and S. misakiensis JCM 4062T. Consequently, strain NEAU-G9T represents a novel species of the genus Streptomyces, for which the name Streptomyces polygonati sp. nov. is proposed. The type strain is NEAU-G9T ( = CGMCC 4.7237T = DSM 100521T).

A novel actinomycete, designated strain 1C-HV12T, was isolated from the cuticle of Camponotus japonicas Mayr and characterized using a polyphasic approach. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the organism should be assigned to the genus Promicromonospora and that it forms a monophyletic clade with the closest relatives Promicromonospora umidemergens JCM 17975T(99.17 % 16S rRNA gene sequence similarity), Promicromonospora vindobonensis V45T (98.88 %) and Promicromonospora iranensis HM 792T (98.85 %). Moreover, morphological and chemotaxonomic properties of strain 1C-HV12T also confirmed the affiliation of the isolate to the genus Promicromonospora. The peptidoglycan hydrolysates contained alanine, glutamic acid and lysine, and whole-cell sugars were galactose, glucose, rhamnose and ribose. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, an unidentified phosphoglycolipid, an unidentified phospholipid and an unidentified glycolipid. The major menaquinones were MK-9(H4) and MK-9(H2). The predominant cellular fatty acids were anteiso-C15 : 0, iso-C15 : 0 and anteiso-C17 : 0. The DNA G+C content was 71.6 mol%. However, the low level of DNA–DNA relatedness and some phenotypic characteristics allowed the isolate to be differentiated from closely related species. Therefore, it is concluded that strain 1C-HV12T represents a novel species of the genus Promicromonospora, for which the name Promicromonospora alba sp. nov. is proposed. The type strain is 1C-HV12T ( = CGMCC 4.7283T = DSM 100490T).