Héctor Herrera, Tedy Sanhueza, Rafael Borges Da Silva Valadares, Francisco Matus, Guillermo Pereira, Cristian Atala, María de la Luz Mora, Cesar Arriagada. 2022. Diversity of the root-associated fungi of the terrestrial orchids Gavilea lutea and Chloraea collicensis in temperate forest soils of south-central Chile.Journal of Fungi. 8(8), 794. (WOS. Impact Factor 5.724  Q1).

Roxana Alvarado, Alejandra Fuentes, Javier Ortiz, Hector Herrera, Cesar Arriagada. 2022 Metal(loid)-resistant bacterial consortia with antimycotic properties increase tolerance of Chenopodium quinoa to metal(loid) stress. Rhizosphere 23 (2022) 100569. (WOS. Impact Factor 3.437  Q2).

Héctor Herrera, Alejandra Fuentes, Javier Ortiz, Javiera Soto, Rafael Borges da Silva Valadares, Christian Salas-Eljatib, Cesar Arriagada. 2022. Root-associated endophytes isolated from juvenile Ulex europaeus L. (Fabaceae) plants colonizing rural areas in South-Central Chile. Plant and Soil 474:181–193.(WOS. Impact Factor 4.993  Q1).

Alejandra Fuentes-Quiroz, Hector Herrera, Javiera Soto, Reinaldo Campos, Javier Ortiz, Cesar Arriagada. 2022. Rhizosphere fungi regulate the expression of metal tolerance genes in Solanum lycopersicum L. (Solanaceae) growing in a metal(loid)-contaminated soil. Rhizosphere. Volume 24, December 2022, 100599. (WOS. Impact Factor 3.437  Q2).

Diversity of Root-Associated Fungi of the Terrestrial Orchids Gavilea lutea and Chloraea collicensis in a Temperate Forest Soil of South-Central Chile

Author Full Names: Héctor Herrera, Tedy Sanhueza, Rafael Borges da Silva Valadares, Francisco Matus, Guillermo Pereira, Cristian Atala, María de la Luz Mora and Cesar Arriagada

Source Title: Journal of FUNGI

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.


Root-associated endophytes isolated from juvenile Ulex europaeus L. (Fabaceae) plants colonizing rural areas in South-Central Chile

Author Full Names: Héctor Herrera · Alejandra Fuentes · Javier Ortiz · Javiera Soto · Rafael Borges da Silva Valadares · Christian Salas-Eljatib · Cesar Arriagada

Source TitlePlant Soil

Background and aims Ulex europaeus L. (Fabaceae), commonly known as gorse, is an invasive woody shrub that easily grows in several locations across the world. However, little is known about the interactions of this invasive species with soil micro- organisms and how these microbes can promote rapid grow-rates at early stages of development. We aim to explore this by characterizing the endophytic fun- gal and bacterial microbiota associated with roots of juvenile U. europaeus plants colonizing native eco- systems in south-central Chile.

Methods Root-associated microorganisms were iso- lated and identified using standard molecular tech- niques. Furthermore, plant growth-promoting traits and biocontrol activity of the isolates against phy- topathogenic fungi were assessed to characterize the early growth stage root-associated taxa.

Results Four endophytic fungi belonging to Sord- ariomycetes and twelve bacteria assigned to Proteo- bacteria and Actinobacteria were associated with the early stage of U. europaeus. Plant growth-promoting traits were detected in some isolates such as Fusarium acuminatum and Rhodococcus sp. Additionally, two endophyte isolates Rhodococcus sp. and Purpureocil- lium lilacinum showed biocontrol potential against phytopathogenic fungi tested in this study. Conclusions Our results demonstrate that U. euro- paeus plantlets host several endophytes in the roots, some of which showed biocontrol capabilities and plant growth-promoting traits that can contribute with the rapid growth-rates at juvenile stages of the shrub. The interaction with a set of endophytes demonstrat- ing these beneficial traits is an additional mechanism explaining the ability of U. europaeus to colonize various ecosystems.


Metal(loid)-resistant bacterial consortia with antimycotic properties increase tolerance of Chenopodium quinoa Wild. to metal(loid) stress

Author Full Names: Roxana Alvarado, Alejandra Fuentes, Javier Ortiz, Hector Herrera, Cesar Arriagada

Source TitleRhizosphere

Bacteria associated with plants colonizing extreme environments in Chile (Atacama and Antarctic Desert soils) provide a model to study plant growth-promoting mechanisms that can be useful to improve the growth of crops such as Chenopodium quinoa Wild. (Amaranthaceae) growing under severe environmental conditions. This study aimed to determine the tolerance of extremophile rhizobacteria to multiple metal(loid)s and evaluate the effects of formulated consortia in seed germination and growth-promotion of C. quinoa. In our work, five rhizobacteria were isolated and classified into the bacteria genera Streptomyces, Bacillus, and Pseudomonas. The five bacteria showed optimum growth at 26 ◦C, pH 6, and 1% NaCl. In addition, the isolated were resistant to arsenic, manganese, zinc, copper, chromium and showed plant growth-promoting traits, including indole acetic acid production, siderophores production, phosphate solubilization, ACC deaminase activity, and ammonia produc- tion. According to compatibility tests, three bacterial consortia were formulated: i) consortium A (Pseudomonas sp. and Bacillus sp. (T1B41)); ii) consortium B (Pseudomonas sp. and Bacillus sp. (B2B24)); and iii) consortium C (Streptomyces sp., Bacillus sp. (B2B24) and Bacillus sp. (T3B45)). In vitro antagonism against phytopathogenic fungi showed that Bacillus sp. (B2B24) and Bacillus sp. (T3B45) have a significant level of antagonism (up to 18.7 and 6.8%, respectively) and consortia were the most effective against B. cinerea (up to 100%). Consortia B and C significantly improved the germination rate (%) of C. quinoa seeds (86 ± 3.3 and 77 ± 1.7, respectively) and the number of leaves, wet stem weight, length stem length, wet root weight, and root diameter in the presence of metal(loid)s. Our results showed that rhizobacterial consortia based on extremophile microorganisms can enhance the growth of C. quinoa seedlings under metal(loid) stress, demonstrating beneficial characteristics that may be key in the early stages of development.


Effect of arbuscular mycorrhizal fungi and mycoremediated dry olive residue in lead uptake in wheat plants

Author Full Names: Garcia-Sanchez, Mercedes; Andrea Silva-Castro, Gloria; Sanchez, Alvaro; Arriagada, Cesar; Garcia-Romera, Inmaculada


This study aims to evaluate the role of the extraradical mycelium of arbuscular mycorrhizal fungi in Pb transport. We also investigate how these fungi, alone or combined with the mycoremediated dry olive residue (MDOR), provide protection against Pb. We established a container system consisting of a central compartment and two lateral compartments separated by a hydrophobic membrane. The central compartment was filled with sterilized soil in which wheat plants, inoculated and non-inoculated with Funneliformis mosseae, were grown. The lateral compartments were filled with sterile, Pb-contaminated or MDOR-amended soil or combinations of both. In contrast to shoots and grains, wheat roots accumulated larger amounts of Pb with or without applications of MDOR. The extraradical mycelium (ERM) and the glomalin related protein content were significantly boosted by adding MDOR to Pb-contaminated soil samples. Wheat mot biomass was decreased as the result of Pb contamination with no increases in plant phosphorous (P) uptake. However, MDOR, when added to Pbcontaminated soil samples, only boosted the accumulation of P in roots, with P content and biomass remaining unchanged in wheat shoots and grains. Our study highlights the role of the ERM in Pb transport its accumulation in wheat mots and how the protection effect exerted by AMF seemed to rely on MDOR application by increasing the P uptake rather than Pb.

DOI: 10.1016/j.apsoil.2020.103838

UT (Unique WOS ID): WOS:000609456600020

Rhizosphere fungi regulate the expression of metal tolerance genes in Solanum lycopersicum L. (Solanaceae) growing in a metal(loid)-contaminated soil

Author Full Names: Alejandra Fuentes-Quiroz, Hector Herrera, Javiera Soto, Reinaldo Campos, Javier Ortiz and Cesar Arriagada.


In this study, eight fungal strains were isolated from the rhizosphere of Oenothera picensis Phil., a plant that grows naturally in soil contaminated with metal(loid)s in central Chile. The capacity of the strains to tolerate copper and zinc was evaluated, and their effect on the expression of genes related to metal tolerance in Solanum lycopersicum co-inoculated with arbuscular mycorrhizal fungi. Among the isolates, Lecythophora sp. and Hormonema viticola showed the highest tolerance to Cu (1150 mg Kg-1) and Zn (3200 mg Kg-1), respectively. We detected the highest lactic and oxalic acid production lactic and oxalic acid production in Lecythophora sp. against Cu contamination. In contrast, a higher malic, lactic, and citric acid production was detected in H. viticola against Zn contamination. Regarding the expression involved in metal tolerance, we showed that both fungi reduce the expression of the genes MT, PCS, HSP, and NRAMP in S. lycopersicum growing under metal stress. We did not observe a significant positive effect of the co-inoculation with the arbuscular mycorrhizal fungus Rhizophagus irregularis in the relative expression genes in leaves, but a positive impact was detected in roots. The results showed that the co-inoculation of rhizosphere metal-tolerant fungi isolated from metallophyte species and mycorrhizal fungi decreased the expression of metal tolerance genes in S. lycopersicum growing under toxic Cu and Zn levels.


Controlled mycorrhization of the endemic Chilean orchidChloraea gavilu(Orchidaceae)

Author Full Names: Pereira, Guillermo; Herrera, Hector; Arriagada, Cesar; Cid, Hertes; Garcia, Jose Leonardo; Atala, Cristian


Orchids require mycorrhizal fungi (OMF) for their germination and growth. Propagation and re-introduction initiatives would likely require inoculation with such fungi. All Chilean Orchidaceae species are terrestrial and likely associate with OMF. We collected adult individuals of the endemic Chilean orchidChloraea gaviluand transported them to a glasshouse where we obtained mature capsules through manual auto-pollination. We asymbiotically germinated seeds in vitro using Malmgren Modified Terrestrial Orchid-Medium (MM). Embryos were put in glass flasks with MM where roots and leaves developed for 16 weeks. Plants were then transplanted to 165 mL pots and randomly separated into three groups; plants inoculated separately withCeratobasidiumOMFs isolated from two Chilean orchid species (Chloraea virescensandCodonorchis lessonii), and uninoculated (control) plants. Plants were then put in a growth chamber. Three months later, inoculated individuals showed pelotons inside parenchyma cells in the roots. Four months after inoculation, mycorrhizal plants had higher root and shoot biomass compared to control plants. At the end of the experiment, the highest mycorrhization was achieved with theCeratobasidiumstrain isolated fromC. lessonii. The artificial mycorrhization of endemic orchids could be a key strategy for future conservation and propagation initiatives, especially for endangered or commercially interesting species.

DOI: 10.1080/11263504.2020.1801875

UT (Unique WOS ID): WOS:000562194000001