Plant growth-promoting activities of bacterial endophytes isolated from the medicinal plant Pairs polyphylla var. yunnanensis.

Pairs polyphylla var. yunnanensis (Paris L.) is a valuable medicinal plant used in traditional Chinese medicine. The market demand for P. polyphylla has increased over time, but it has slow growth and a low natural propagation rate. Endophytic bacteria are bioactive microorganisms that form a mutualistic relationship with host plants in long-term coordinated evolution, and they can promote the growth and accumulation of effective components in host plants. The aims of this study were to identify endophytic bacteria of P. polyphylla and to characterize their properties in promoting plant growth. A total of 10 endophytic bacteria were isolated from rhizomes of P. polyphylla. The isolated endophytes exhibited a variable capacity for indole acetic acid production, phosphate solubilization and nitrogen fixation. To investigate the effects of the endophytes on plant growth, four endophyte strains, G5, J2, G20, and Y2, were selected to compare their ability to promote plant growth. The results indicated that microbial endophytes isolated from P. polyphylla rhizomes play a vital role in improving P. polyphylla plant growth and could be used as inoculants to establish a sustainable crop production system.

Paenibacillus paridis sp. nov., an endophytic bacterial species isolated from the root of Paris polyphylla Smith var. yunnanensis.

A Gram-reaction-positive, endospore-forming and rod-shaped bacterial strain, designated py1325T, was isolated from the root of Paris polyphylla Smith var. yunnanensis collected from Yunnan Province, PR China, and subjected to a polyphasic taxonomic characterization. It grew optimally with 0-1 % NaCl (w/v), at pH 7 and at 30 °C. The major respiratory quinone was MK-7 and the diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The major cellular fatty acid was anteiso-C15 : 0. The polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, two unidentified aminophospholipids, two unidentified phospholipids and two unidentified lipids. The results of 16S rRNA gene sequence analysis revealed the highest levels of sequence similarity with respect to Paenibacillus luteus R-3T (99.0 %), Paenibacillus sinopodophylli CCTCC AB 2016047T (97.9 %), Paenibacillus castaneae DSM 19417T (97.5 %) and Paenibacillus endophyticus LMG 27297T (97.2 %). The digital DNA-DNA hybridization and average nucleotide identity values between py1325T and these species ranged 20.6-53.3 % and 79.9-93.6 %. The G+C content of the genomic DNA was 47.7 mol%. According to the phylogenetic, phenotypic and chemotaxonomic evidence, strain py1325T clearly represents a novel species of the genus Paenibacillus, for which the name Paenibacillus paridis sp. nov. is proposed. The type strain is py1325T (=CCTCC AB 2015220T=LMG 29068T).

Botrytis polyphyllae: A New Botrytis Species Causing Gray Mold on Paris polyphylla.

Paris polyphylla is an important perennial medicinal plant in China. A disease similar to gray mold on P. polyphylla occurred at the seedling stage in March 2016 and 2017 in Tengchong city, Yunnan Province of China. The disease resulted in up to 50% mortality in serious cases. Isolates from diseased plants grew 10.6 mm/day at 20°C on PDA. After 21 days, sclerotia were spherical to elliptical (0.4-2.5 × 0.3-1.8 mm). Conidia from diseased tissues were hyaline to pale brown, long, ovoid, unicellular, and measured 15.1-24.5 × 8.8-13.4 µm; conidiophores were 526-1,064 ×12-15 µm. Isolates did not form conidiophores or conidia on PDA or MYA. A phylogenetic analysis based on G3PDH, RPB2, and HSP60 sequence data supported assignment of three representative isolates as a new species of Botrytis. Based on morphological, phylogenetic characteristics and Koch's Postulates, the causal agent of gray mold on P. polyphylla was identified as a novel species, Botrytis polyphyllae.

Glycomyces paridis sp. nov., isolated from the medicinal plant Paris polyphylla.

Three actinomycete strains originating from the surface-sterilized roots of Paris polyphylla were characterized by using a polyphasic approach. Phylogenetic analyses based on the 16S rRNA gene sequence showed that they formed a deep, monophyletic branch in the genus Glycomyces, and were most closely related to the type strains of the species Glycomyces harbinensis and Glycomycesscopariae. Morphological and chemotaxonomic data supported the affiliation of strains CPCC 204357T, CPCC 204354 and CPCC 204355 to the genus Glycomyces. The results of physiological and biochemical tests allowed phenotypic differentiation of strains CPCC 204357T, CPCC 204354 and CPCC 204355 from their closest phylogenetic related species in the genus Glycomyces. Low levels of DNA-DNA relatedness with its closest type strains of G. harbinensis and G. scopariaeindicated that strain CPCC 204357T represent a novel species, for which the name Glycomyces paridis sp. nov. is proposed, with CPCC 204357T (=DSM 102295T=KCTC 39745T) as the type strain.

Yimella radicis sp. nov., an endophytic actinobacterium isolated from the root of Paris polyphylla Smith var. yunnanensis.

An endophytic actinobacterial strain, designated py1292T, was isolated from the root of Paris polyphylla Smith var. yunnanensis collected from Yunnan province, China, and subjected to a polyphasic taxonomic characterization. Phylogenetic analysis based on 16S rRNA gene sequences placed the isolate in the family Dermacoccaceae and clustered with Yimella lutea (showing the highest similarity of 99.1 %). DNA-DNA relatedness between strain py1292T and Y. lutea YIM 45900T was 45.6±3.2 % (reciprocal 47.8±3.6 %). The novel isolate was found to be a Gram-staining-positive rod, catalase- and oxidase-positive. It grew at pH 6.0-8.0, with 0-9 % NaCl and at 20-45 ºC, optimally at pH 7.0, with 0-3 % NaCl and at 28 ºC. The predominant menaquinone was MK-8(H4), while the polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, two unknown phospholipids and two unknown polar lipids. The major cellular fatty acids were iso-C15 : 0, iso-C16 : 0, iso-C17 : 0 and anteiso-C17 : 0. The whole-cell hydrolysates contained mannose, ribose, rhamnose, glucose and galactose. The peptidoglycan contained alanine, glycine, serine, aspartic acid, glutamic acid and lysine. The genomic DNA G+C content was determined to be 65.6 mol%. Phylogenetic, phenotypic and chemotaxonomic data (especially the same peptidoglycan type) showed that strain py1292T should be classified as a representative of a novel species of the genus Yimella, for which the name Yimella radicis sp. nov. is proposed. The type strain is py1292T (=KCTC 39612T=LMG 29070T).

Oceanobacillus endoradicis sp. nov., an endophytic bacterial species isolated from the root of Paris polyphylla Smith var. yunnanensis.

A bacterial strain, py1294(T), isolated from a root of Paris polyphylla Smith var. yunnanensis collected from Yunnan province, southwest China, was characterised by using a polyphasic approach to clarify its taxonomic position. Strain py1294(T) was found to be Gram-positive, aerobic, spore-forming, peritrichous flagella and rod shaped. Growth was found to occur in the presence of 0-8 % (w/v) NaCl (optimum 1-3 %), at pH 6.5-9.5 (optimum 8.0) and at 10-42 °C (optimum 30 °C). The major cellular fatty acids were identified as anteiso-C15:0, anteiso-C17:0, iso-C16:0 and iso-C14:0. The predominant quinone was identified as MK-7 and a minor amount of MK-6 was detected. The diagnostic polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The cell wall peptidoglycan was found to contain meso-diaminopimelic acid. Phylogenetic analysis of the 16S rRNA gene sequence showed that strain py1294(T) forms a well-supported clade with Oceanobacillus damuensis PT-20(T) (97.9 % sequence similarity) within the genus Oceanobacillus, although it also shares a high sequence similarity with Ornithinibacillus contaminans (97.5 %). Crucially, the DNA-DNA relatedness value between strain py1294(T) and O. damuensis PT-20(T) was 29.7 ± 3.2 %. The G+C content was determined to be 42.3 mol%. On the basis of the phylogenetic and phenotypic data, a novel species Oceanobacillus endoradicis sp. nov. is proposed, with py1294(T) (=DSM 100726(T) = KCTC 33731(T)) as the type strain.

[A new cytotoxic isocoumarin from endophytic fungus Aspergillus versicolor].

A new isocoumarin, along with five known ones,were isolated from the fermentation products of an endophytic fungus Aspergillus versicolorby using various chromatographic techniques.Their structures were elucidated on the basis of extensivespectroscopic analysis, including 1D-and 2D-NMR techniques. Compound 1 was evaluated for cytotoxicity against five human tumor cell lines. The results showed that 1 exhibited weak cytotoxicityagainst NB4, SHSY5Y and MCF7 cells with IC50 values of 6.8, 4.3,8.8 µmol•L⁻¹, respectively.