Rhizocompartments and environmental factors affect microbial composition and variation in native plants.

Molecular analysis based on large-scale sequencing of the plant microbiota has revealed complex relationships between plants and microbial communities, and environmental factors such as soil type can influence these relationships. However, most studies on root-associated microbial communities have focused on model plants such as Arabidopsis, rice or crops. Herein, we examined the microbiota of rhizocompartments of two native plants, Sedum takesimense Nakai and Campanula takesimana Nakai, using archaeal and bacterial 16S rRNA gene amplicon profiling, and assessed relationships between environmental factors and microbial community composition. We identified 390 bacterial genera, including known plant-associated genera such as Pseudomonas, Flavobacterium, Bradyrhizobium and Rhizobium, and uncharacterized clades such as DA101 that might be important in root-associated microbial communities in bulk soil. Unexpectedly, Nitrososphaera clade members were abundant, indicating functional association with roots. Soil texture/type has a greater impact on microbial community composition in rhizocompartments than chemical factors. Our results provide fundamental knowledge on microbial diversity, community and correlations with environmental factors, and expand our understanding of the microbiota in rhizocompartments of native plants.

Arthrobacter dokdonellae sp. nov., isolated from a plant of the genus Campanula.

A Gram-stain-positive, oxidase- and catalase-positive motile, aerobic, and rod-shaped bacterial strain, designated as DCT-5T, was isolated from a native plant belonging to the genus Campanula at Dokdo island, Republic of Korea. Growth of the strain DCT-5T was observed at 15-37°C (optimum 30°C) on R2A broth, pH 6.0-8.0 (optimum 7.0), and 0-5% (w/v) NaCl concentration (optimum 0%). The 16S rRNA gene sequence analysis revealed that strain DCT-5T was most closely related to Arthrobacter silviterrae KIS14-16T, Arthrobacter livingstonensis LI2T, Arthrobacter stackebrandtii CCM 2783T, Arthrobacter cryoconiti Cr6-08T, Arthrobacter ramosus CCM 1646T, and Arthrobacter psychrochitiniphilus GP3T with pairwise sequence similarities of 98.76%, 97.47%, 97.25%, 97.11%, 97.11%, and 97.00%, respectively. The DNA G+C content of strain DCT-5T was 64.7 mol%, and its DNA-DNA relatedness values with A. silviterrae KIS14-16T, A. livingstonensis LI2T, A. stackebrandtii CCM 2783T, A. psychrochitiniphilus GP3T, A. ramosus CCM 1646T, and A. cryoconiti Cr6-08T were 32.57 ± 2.02%, 28.75 ± 0.88%, 31.93 ± 1.15%, 34.73 ± 1.86%, 29.12 ± 1.56%, and 27.23 ± 0.88%, respectively. The major quinone was MK-9(H2) and major fatty acids were anteiso-C15:0, anteiso-C17:0, iso-C15:0, and iso-C16:0. The polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylinositol (PI), unidentified glycolipid (GL), two unidentified aminophospholipids (APLs), and three unidentified lipids (Ls). The peptidoglycan type was A3α. On the basis of phenotypic, phylogenetic, genotypic, and chemotaxonomic characteristics, strain DCT-5T represents a novel species of the genus Arthrobacter, for which the name Arthrobacter dokdonellae sp. nov. is proposed. The type strain is DCT-5T (= KCTC 49189T = LMG 31284T).

Paraburkholderia dokdonella sp. nov., isolated from a plant from the genus Campanula.

The novel Gram-stain-negative, rod-shaped, aerobic bacterial strain DCR-13T was isolated from a native plant belonging to the genus Campanula on Dokdo, an island in the Republic of Korea. Comparative analysis of the 16S rRNA gene sequence indicated that this strain is closely related to Paraburkholderia peleae PP52-1T (98.43% 16S rRNA gene sequence similarity), Paraburkholderia oxyphila NBRC 105797T (98.42%), Paraburkholderia sacchari IPT 101T (98.28%), Paraburkholderia mimosarum NBRC 106338T (97.80%), Paraburkholderia denitrificans KIS30-44T (97.46%), and Paraburkholderia paradise WAT (97.45%). This analysis of the 16S rRNA gene sequence also suggested that DCR-13T and the six closely related strains formed a clade within the genus Paraburkholderia, but that DCR-13T was clearly separated from the established species. DCR-13T had ubiquinone 8 as its predominant respiratory quinone, and its genomic DNA G + C content was 63.9 mol%. The isolated strain grew at a pH of 6.0-8.0 (with an optimal pH of 6.5), 0-4% w/v NaCl (with an optimal level of 0%), and a temperature of 18-42°C (with an optimal temperature of 30°C). The predominant fatty acids were C16:0, summed feature 8 (C18:1ω7c/C18:1ω6c), C17:0 cyclo, C19:0 cyclo ω8c, summed feature 3 (C16:1ω6c/C16:1ω7c) and summed feature 2 (C12:0 aldehyde), and the major polar lipids were phosphatidylglycerol and phosphatidylethanolamine. On the basis of polyphasic evidence, it is proposed that strain DCR-13T (= KCTC 62811T = LMG 30889T) represents the type strain of a novel species, Paraburkholderia dokdonella sp. nov.

Paenibacillus seodonensis sp. nov., isolated from a plant of the genus Campanula.

Strain DCT-19T, representing a Gram-stain-positive, rodshaped, aerobic bacterium, was isolated from a native plant belonging to the genus Campanula on Dokdo, the Republic of Korea. Comparative analysis of the 16S rRNA gene sequence showed that this strain was closely related to Paenibacillus amylolyticus NRRL NRS-290T (98.6%, 16S rRNA gene sequence similarity), Paenibacillus tundrae A10bT (98.1%), and Paenibacillus xylanexedens NRRL B-51090T (97.6%). DNADNA hybridization indicated that this strain had relatively low levels of DNA-DNA relatedness with P. amylolyticus NRRL NRS-290T (30.0%), P. xylanexedens NRRL B-51090T (29.0%), and P. tundrae A10bT (24.5%). Additionally, the genomic DNA G + C content of DCT-19T was 44.8%. The isolated strain grew at pH 6.0-8.0 (optimum, pH 7.0), 0-4% (w/v) NaCl (optimum, 0%), and a temperature of 15-45°C (optimum 25-30°C). The sole respiratory quinone in the strain was menaquinone-7, and the predominant fatty acids were C15:0 anteiso, C16:0 iso, and C16:0. In addition, the major polar lipids were diphosphatidylglycerol and phosphatidylethanolamine. Based on its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain DCT-19T is proposed as a novel species in the genus Paenibacillus, for which the name Paenibacillus seodonensis sp. nov. is proposed (=KCTC 43009T =LMG 30888T). The type strain of Paenibacillus seodonensis is DCT-19T.

Wickerhamiella kiyanii f.a., sp. nov. and Wickerhamiella fructicola f.a., sp. nov., two yeasts isolated from native plants of Atlantic rainforest in Brazil.

Two novel species, Wickerhamiella kiyanii f.a., sp. nov. (type strain FB1-1DASP(T) = CBS 12905(T) = CBMAI 1613(T)) and Wickerhamiella fructicola f.a., sp. nov. (type strain H10Y(T) = CBS 12902(T) = CBMAI 1614(T)) are proposed in the Wickerhamiella clade (Saccharomycetes, Saccharomycetales) to accommodate three strains isolated from flowers and fruits typical of the Brazilian Atlantic rainforest. The novel status of these yeast species was established by sequence divergence observed in the D1/D2 domains of the LSU rRNA gene from the most closely related, described species as well as by phylogenetic analysis. Wickerhamiella kiyanii sp. nov. differs from its nearest phylogenetic neighbours W. pagnoccae CBS 12178(T), Candida jalapaonensis CBS 10935(T) and Candida drosophilae CBS 8459(T) by 2.2-4.2% in the D1/D2 sequences. By contrast, a sequence divergence of 13.2-13.8% was observed between W. fructicola sp. nov. and its closest, described phylogenetic relative Candida kazoui JCM 12558(T) and Candida hasegawae JCM 12559(T). Taxonomic descriptions of the two novel species are given.

Hanseniaspora nectarophila sp. nov., a yeast species isolated from ephemeral flowers.

Seven apiculate yeast strains that were isolated from the flowers of Syphocampylus corymbiferus Pohl in Brazil are genetically, morphologically and phenotypically distinct from recognized species of the genera Hanseniaspora and Kloeckera. Genetic discontinuities between the novel strains and their closest relatives were found using a networking approach based on the concatenated sequences of the rRNA gene (internal transcribed spacer and D1/D2 of the LSU), and the protein-coding genes for actin and translation elongation factor-1α. Phylogenetic analysis based on the rRNA and the actin gene placed the novel species represented by the strains in close relationship to Hanseniaspora meyeri and Hanseniaspora clermontiae. PCR fingerprinting with microsatellite primers confirmed the genetic heterogeneity of the novel species. The name Hanseniaspora nectarophila sp. nov. is proposed, with UFMG POG a.1(T) ( = ZIM 2311(T)  = CBS 13383(T)) as the type strain; MycoBank no. MB807210. As the current description of the genus does not allow the presence of multilateral budding, an emended diagnosis of the genus Hanseniaspora Zikes is proposed.

Wickerhamomyces queroliae sp. nov. and Candida jalapaonensis sp. nov., two yeast species isolated from Cerrado ecosystem in North Brazil.

Two novel yeast species, Wickerhamomyces queroliae sp. nov. and Candida jalapaonensis sp. nov., were isolated, respectively, from larvae of Anastrepha mucronata (Diptera: Tephritidae) collected from ripe fruit of Peritassa campestris ('Bacupari', Hippocrateaceae) and from flowers of Centropogon cornutus (Campanulaceae) in the Cerrado ecosystem of the state of Tocantins, Brazil. Analysis of the D1/D2 large-subunit rRNA gene sequences placed W. queroliae in the Wickerhamomyces clade near Wickerhamomyces ciferri and Candida silvicultrix. Candida jalapaonensis belongs to the Wickerhamiella clade and is related to Candida drosophilae. The type strain of Wickerhamomyces queroliae is UFMG-05-T200.1(T) (=CBS 10936(T)=NRRL Y-48478(T)) and the type strain of Candida jalapaonensis is UFMG-03-T210(T) (=CBS 10935(T)=NRRL Y-48477(T)).

Community structure of arbuscular mycorrhizal fungi in a primary successional volcanic desert on the southeast slope of Mount Fuji.

Community structure of arbuscular mycorrhizal fungi (AMF), evaluated as spore samples and mycorrhizal roots of four herbaceous plant species, was investigated at different altitudes in a primary successional volcanic desert on Mount Fuji using molecular methods (fragment and sequence analysis of the large ribosomal subunit RNA gene). In total, 17 different AMF clades were identified, and most were members of the Glomaceae, Acaulosporaceae, and Gigasporaceae. The AMF community structures detected by spore sampling were inconsistent with those from plant roots. Of all AMF clades, six (35.3%) were detected only on the basis of spores, six (35.3%) only in roots, and five corresponded to both spores and roots (29.4%). Although an Acaulospora species was the most dominant among spores (67.1%), it accounted for only 6.8% in root samples. A species analysis of AMF communities at different altitudes demonstrated that AMF species diversity increased as altitude decreased and that the species enrichment at lower altitudes resulted from the addition of new species rather than species replacement. The inconsistencies in the species composition of spore communities with those in roots and the change in species diversity with altitude are discussed.

Chaetominine, a cytotoxic alkaloid produced by endophytic Chaetomium sp. IFB-E015.

Chaetominine (1), an alkaloidal metabolite with a new framework, was characterized from the solid-substrate culture of Chaetomium sp. IFB-E015, an endophytic fungus on the apparently healthy Adenophora axilliflora leaves. Its structure was determined by a combination of its spectral data and single-crystal X-ray diffraction analysis, with its absolute configuration elucidated by Marfey's method. Chaetominine was more cytotoxic than 5-fluorouracil against the human leukemia K562 and colon cancer SW1116 cell lines. [structure: see text]

Arbuscular mycorrhizal colonization of the dominant plant species in primary successional volcanic deserts on the Southeast slope of Mount Fuji.

Arbuscular mycorrhizal (AM) colonization was observed on four plant species in primary successional volcanic deserts on the Southeast slope of Mount Fuji. The AM colonization of the dominant species, Polygonum cuspidatum, contradicts the conclusion that Polygonaceae are often regarded as being non-mycorrhizal species. The secondary dominant species, Polygonum weyrichii var. alpinum, formed no mycorrhizas. The roots of Cirsium purpuratum, Clematis stans and Campanula punctata ssp. hondoensis, showed a higher percentage of AM colonization than P. cuspidatum. AM colonization and spore density in the rhizosphere soil of P. cuspidatum significantly decreased as elevation increased. AM colonization in roots of Cirsium purpuratum and Clematis stans also tended to decrease with increased altitudes. Cirsium purpuratum and Campanula punctata ssp. hondoensis formed single structural types of Arum- and Paris-type, respectively, whereas P. cuspidatum and Clematis stans formed both Arum- and Paris-type morphologies.

Agrobacterium tumefaciens-mediated transformation of Campanula carpatica: factors affecting transformation and regeneration of transgenic shoots.

An efficient transformation system for Campanula carpatica was developed using Agrobacterium tumefaciens strains LBA4404 (harbouring the plasmid pBI121), and AGL0 (harbouring the plasmid pBEO210). This is the first report on the transformation of C. carpatica. Various factors affecting the transformation efficiency and subsequent regeneration were identified. The age of seedlings from which the explants for transformation studies were taken, and the growth conditions under which the seedlings were grown had a significant influence on the production of transformed shoots. Hypocotyls taken from 12-day-old seedlings grown in the dark were the most productive, with up to 25% of hypocotyls producing transformed shoots. Explants taken from 5-week-old seedlings produced only transformed callus. The medium used for co-cultivation and incubation also had a significant influence on transformation frequency and shoot regeneration. The cultivar "Blue Uniform" was more responsive than "White Uniform". Both bacterial strains and plasmids were equally effective in producing transformed tissue. Transformed shoots were selected on kanamycin medium, and the presence of the uidA and nptII genes in those selected shoots was confirmed by beta-glucuronidase and ELISA analyses, respectively.

Arbuscular mycorrhizal distribution in relation to microsites on recent volcanic substrates of Mt. Koma, Hokkaido, Japan.

Mycorrhizae occur in most terrestrial ecosystems and are crucial to understanding community structure and function. However, their role in primary succession is poorly understood. This study examined the mycorrhizal colonization of six plant species in relation to microsite types on recent volcanic substrates on the summit of Mt. Koma, Hokkaido, Japan. The six microsites were flat, rill, near rock, Carextussock, Polygonum patch and Salix patch. Carex oxyandra was nonmycorrhizal and Agrostis scabra and Campanula lasiocarpa were arbuscular mycorrhizal (AM) at all microsites examined. Agrostis AM colonization levels did not differ across microsites. Near rock Campanula roots contained significantly more hyphae than at flat and Polygonum patch microsites, and rill and Carex tussock Campanula more arbuscules than at Polygonum patches. Penstemon frutescens was found to be facultatively mycotrophic with AM colonization occurring in roots of Penstemon growing in Carex tussocks, Polygonum patches and near rocks. Polygonum weyrichii was found to be ectomycorrhizal. Polygonum located in rills and in Polygonum and Salix patches were more colonized than Polygonum in Carex patches. Salix reinii was heavily ectomycorrhizal.