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The diversity of orchid mycorrhizal fungi (OMF) and other beneficial root-associated fungi in temperate forests has scarcely been examined. This study aimed to analyze the diversity of mycorrhizal and rhizosphere-associated fungal communities in the terrestrial orchids Gavilea lutea and Chloraea collicensis growing in high-orchid-population-density areas in the piedmont of the Andes Cordillera with native forest (Nothofagus-Araucaria) and Coastal Cordillera with an exotic plantation (Pinus-Eucalyptus) in south-central Chile. We focused on rhizosphere-inhabiting and peloton-associated OMF in a native forest (Andes Cordillera) and a mixed forest (Coastal Cordillera). The native terrestrial orchids G. lutea and C. collicensis were localized, mycorrhizal root segments were taken to isolate peloton-associated OMF, and rhizosphere soil was taken to perform the metabarcoding approach. The results revealed that Basidiomycota and Ascomycota were the main rhizosphere-inhabiting fungal phyla, showing significant differences in the composition of fungal communities in both sites. Sebacina was the most-abundant OMF genera in the rhizosphere of G. lutea growing in the native forest soil. In contrast, Thanatephorus was the most abundant mycorrhizal taxa growing in the rhizosphere of orchids from the Coastal Cordillera. Besides, other OMF genera such as Inocybe, Tomentella, and Mycena were detected. The diversity of OMF in pelotons differed, being mainly related to Ceratobasidium sp. and Tulasnella sp. These results provide evidence of differences in OMF from pelotons and the rhizosphere soil in G. lutea growing in the Andes Cordillera and a selection of microbial communities in the rhizosphere of C. collicensis in the Coastal Cordillera. This raises questions about the efficiency of propagation strategies based only on mycorrhizal fungi obtained by culture-dependent methods, especially in orchids that depend on non-culturable taxa for seed germination and plantlet development. [ABSTRACT FROM AUTHOR]

Understanding features that fostered the persistence of Equisetum–Earth's oldest extant vascular plant genus–since Mesozoic times and through episodes of significant global environmental change, is of current interest in view of modern challenges to plant survival. In addition to known structural and physiological adaptations, we hypothesized that microscopy and shotgun metagenomic sequencing might reveal eukaryotic microorganisms such as fungi that may aid Equisetum survival. Here, we report evidence for several lineages of eukaryotic microbes associated with giant Equisetum xylochaetum, which dominates vegetation in saline streambeds of remote valleys in the hyper-arid Atacama Desert, Chile. Plant material was collected and field-preserved at two comparatively low-disturbance sites; DNA extracted in Chile using low-shear methods was later sequenced, 18S and 28S rDNA taxonomic marker sequences were selected for SILVAngs classification, allowing comparisons to eukaryotic microorganisms previously inferred for earlier-diverging plant lineages. SEM, fluorescence microscopy, and/or LM of toluidine blue-stained sections of roots indicated protists, epiphytic and endophytic fungi, and cortical nematodes. Eukaryotic genera inferred from 18S rDNA at >100X mean sequencing depth included the ciliate Engelmanniella, hyphal chytrid Monoblepharella, predatory ascomycete Cephaliophora, a salpingoecid choanoflagellate, and an annelid worm. 23S rDNA sequences indicated ascomycete Capnodiales fungi at one site and four types of Pezizomycotina fungi at the other. No evidence for vesicular-arbuscular mycorrhizal fungi was found, but we hypothesized that Equisetum may benefit from other types of fungal associations, some possibly inherited from ancestral plant lineages. [ABSTRACT FROM AUTHOR]

Mycorrhizal interactions of orchids are influenced by several environmental conditions. Hence, knowledge of mycorrhizal fungi associated with orchids inhabiting different ecosystems is essential to designing recovery strategies for threatened species. This study analyzes the mycorrhizal associations of terrestrial orchids colonizing grassland and understory in native ecosystems of the region of La Araucanía in southern Chile. Mycorrhizal fungi were isolated from peloton-containing roots and identified based on the sequence of the ITS region. Their capacities for seed germination were also investigated. We detected Tulasnella spp. and Ceratobasidium spp. in the pelotons of the analyzed orchids. Additionally, we showed that some Ceratobasidium isolates effectively induce seed germination to differing degrees, unlike Tulasnella spp., which, in most cases, fail to achieve protocorm growth. This process may underline a critical step in the life cycle of Tulasnella-associated orchids, whereas the Ceratobasidium-associated orchids were less specific for fungi and were effectively germinated with mycorrhizal fungi isolated from adult roots. [ABSTRACT FROM AUTHOR]

Endophytic bacteria are relevant symbionts that contribute to plant growth and development. However, the diversity of bacteria associated with the roots of terrestrial orchids colonizing Andean ecosystems is limited. This study identifies and examines the capabilities of endophytic bacteria associated with peloton-containing roots of six terrestrial orchid species from southern Chile. To achieve our goals, we placed superficially disinfected root fragments harboring pelotons on oatmeal agar (OMA) with no antibiotic addition and cultured them until the bacteria appeared. Subsequently, they were purified and identified using molecular tools and examined for plant growth metabolites production and antifungal activity. In total, 168 bacterial strains were isolated and assigned to 8 OTUs. The orders Pseudomonadales, Burkholderiales, and Xanthomonadales of phylum Proteobacteria were the most frequent. The orders Bacillales and Flavobacteriales of the phylla Firmicutes and Bacteroidetes were also obtained. Phosphate solubilization was detected in majority of isolates; however, it was significantly higher in Collimonas pratensis and Chryseobacterium sp. (PSI = 1.505 ± 0.09 and 1.405 ± 0.24, respectively). Siderophore production was recorded only for C. pratensis (0.657 ± 0.14 mm day−1), Dyella marensis (0.131 ± 0.02 mm day−1), and Luteibacter rhizovicinus (0.343 ± 0.12 mm day−1). Indole acetic acid production was highly influenced by the isolate identity; however, the significantly higher activity was recorded for Pseudomonas spp. (ranging from 5.507 ± 1.57 µg mL−1 to 7.437 ± 0.99 µg mL−1). Additionally, six bacterial isolates were able to inhibit the growth of some potential plant pathogenic fungi. Our findings demonstrate the potential for plant growth promoting capabilities and some antifungal activities of endophytic bacteria inhabiting the mycorrhizal tissue of terrestrial orchids, which may contribute especially at early developmental stages of orchid seedlings. [ABSTRACT FROM AUTHOR]

The microbiological interactions of the roots of non-photosynthetic plants in South America have been scarcely explored. This study analyzes culturable fungal diversity associated with the mycoheterotrophic plant Arachnitis uniflora Phil. (Corsiaceae) in southern Chile, growing in two different understoreys of native (Nothofagus-dominated) and mixed forest (native, Cupressussempervirens, and Pinusradiata). Rhizospheric and endophytic fungi were isolated, cultured, and purified to identify microorganisms associated with A. uniflora roots. We showed the different fungi associated with the plant, and that these distributions are influenced by the sampling site. We isolated 410 fungal strains (144 endophytic and 266 from the rhizosphere). We identified 13 operative taxonomical units from plants sampled in the mixed forest, while 15 were from the native forest. Rhizospheric microorganisms were mainly related to Penicillium spp., whereas some pathogenic and saprophytic strains were more frequent inside the roots. Our results have also shown that the fungal strains are weak for phosphate solubilization, but other pathways such as organic acid exudation and indole acetic acid production can be considered as major mechanisms to stimulate plant growth. Our results point to new fungal associates of A. uniflora plants reported in Andean ecosystems, identifying new beneficial endophytic fungi associated with roots of this fully mycoheterotrophic plant. [ABSTRACT FROM AUTHOR]