Daniel Chávez

Morels are highly valued edible mushrooms due to their ecological and nutraceutical importance. However, nutritional studies in South America are still scarce. This study evaluated the mineral, nutritional, and bioactive properties of Morchella eximia, M. importuna, M. tridentina, and the endemic M. andinensis, which naturally fruits in forest plantations (FPs) and native forests (NFs) in south-central Chile. Soils differed significantly, indicating varied fertility levels across morel habitats. Ascocarps from all species exhibited significant accumulation of K and P, with moderate accumulation of Ni and Zn. Cd and Pb remained within internationally accepted safe limits, while As was undetectable. The determination of the translocation factor, performed only on M. andinensis and M. tridentina, indicated a preferential translocation of K and P to the pileus. Differences were observed among the species in terms of phenolic content and antioxidant activity. A proximate analysis revealed that Chilean morels had elevated levels of protein and fiber, similar to those reported in morels from other latitudes. An exploratory multivariate analysis suggested that the observed variation in mineral composition and bioactive and nutritional properties of Chilean morels likely reflects the combined influence of soil characteristics, forest environment, and genotype traits. These preliminary results are the first to describe traits related to the nutritional quality of Morchella spp. from south-central Chile.

True morels (Morchella spp.) in South America are poorly documented, despite their high gastronomic and ecological value. In this study, morel ascomata were collected from various environments in south-central Chile, and their in vitro physiological performance was characterized. The endemic species Morchella andinensis, along with the transcontinental M. tridentina, M. eximia, and M. importuna, were identified, pure isolates obtained and then cultivated under various conditions. The carbon supplements had a significant effect on mycelial performance, with mannose and pectin yielding high growth rates (~13 mm·day⁻¹) and biomass production (~100 mg·plate⁻¹). Carboxymethylcellulose consistently reduced growth across all strains. Depending on the strain, organic nitrogen supplements such as peptone and amino acids promoted growth more than inorganic nitrogen such as ammonium sulfate. Most strains demonstrated higher performance at pH 7.2–8.5 and 24 °C, and sclerotia formation was strongly strain-dependent. An exploratory principal component analysis (PCA) descriptively summarized the standardized physiological response profiles of the eight selected strains. In this analysis, M. importuna strains were associated with generally higher growth responses, while M. tridentina T140 and M. eximia E87 showed comparatively lower responses. The M. andinensis strains occupied intermediate positions in the multivariate space. The results indicate significant physiological differences among Morchella strains. This underscores the importance of strain-level evaluation as a preliminary step for future studies on strain preservation, artificial cultivation trials, and biotechnological investigations of morels in Chile.

Los hongos endófitos [HE] son microorganismos que viven dentro de las plantas sin causar daño aparente, y colaboran en la síntesis de sustancias reguladoras del crecimiento, fijación de nitrógeno, protección contra patógenos, entre otros beneficios para las plantas. En este estudio se determinó la capacidad de producción de ácido indol acético [AIA] y de solubilización de fosfato, en cuatro cepas de HE aislados desde raíces de Araucaria araucana y se evaluó su efecto sobre la promoción del crecimiento en Nicotiana tabacum, utilizada como planta modelo. Los hongos fueron identificados como Phialocephala fortinii (cepa E-1), Penicillium melinii (cepa E-13), Umbelopsis dimorpha (cepa E-14) y Preussia cymatomera (cepa E-36). El AIA fue determinado utilizando el método de Salkowski, usando caldo de papa dextrosa {CPD] suplementado con 10 mg L-1 de L-triptófano, como precursor para la síntesis de AIA, y la producción fue expresada en mg L-1. La solubilización de fosfato fue determinada en medio sólido Pikovskaya, evaluando los halos formados en el medio y calculando el índice de eficiencia relativa de solubilización {ERS]. Finalmente, la estimulación del crecimiento vegetal por los HE en un co-cultivo con las plántulas de N. tabacum, en condiciones in vitro, fue evaluada a través de la producción de biomasa aérea y radicular de las plántulas. Los mayores valores de AIA y ERS fueron obtenidos con U. dimorpha (52,29 y 3,36 mg L-1, respectivamente). Los hongos utilizados promovieron el crecimiento de la biomasa aérea y radicular de las plantas de N. tabacum en condiciones in vitro, obteniéndose la mayor producción de biomasa seca total (aérea y radicular) con U. dimorpha, con 188,5 mg, valor significativamente mayor (p < 0,01) que el de las plantas control (8,85 mg). A través de este estudio se infiere que los HE aislados de A. araucana promueven el crecimiento vegetal y brindan beneficios para las plantas mediante la producción de fitohormonas.

In its natural distribution, Araucaria araucana is a plant species usually exposed to extreme environmental constraints such as wind, volcanism, fires, and low rainfall. This plant is subjected to long periods of drought, accentuated by the current climate emergency, causing plant death, especially in its early growth stages. Understanding the benefits that both arbuscular mycorrhizal fungi (AMF) and endophytic fungi (EF) could provide plants under different water regimes would generate inputs to address the above-mentioned issues. Here, the effect of AMF and EF inoculation (individually and combined) on the morphophysiological variables of A. araucana seedlings subjected to different water regimes was evaluated. Both the AMF and EF inocula were obtained from A. araucana roots growing in natural conditions. The inoculated seedlings were kept for 5 months under standard greenhouse conditions and subsequently subjected to three different irrigation levels for 2 months: 100, 75, and 25% of field capacity (FC). Morphophysiological variables were evaluated over time. Applying AMF and EF + AMF yielded a noticeable survival rate in the most extreme drought conditions (25% FC). Moreover, both the AMF and the EF + AMF treatments promoted an increase in height growth between 6.1 and 16.1%, in the production of aerial biomass between 54.3 and 62.6%, and in root biomass between 42.5 and 65.4%. These treatments also kept the maximum quantum efficiency of PSII (Fv/Fm 0.71 for AMF and 0.64 for EF + AMF) stable, as well as high foliar water content (>60%) and stable CO₂ assimilation under drought stress. In addition, the EF + AMF treatment at 25% FC increased the total chlorophyll content. In conclusion, using indigenous strains of AMF, alone or in combination with EF, is a beneficial strategy to produce A. araucana seedlings with an enhanced ability to tolerate prolonged drought periods, which could be of great relevance for the survival of these native species under the current climate change.

In this work Talaromyces australis and Penicillium murcianum pigment production in liquid cultures and the cytotoxic effect of such pigments on skin model cells were studied. Response surface methodology (RSM) was used to optimize culture conditions aiming to increase pigment production in malt extract and peptone-glucose-yeast extract medium. Cytotoxicity of fungal pigments and also from lixiviates of wool fabrics dyed with T. australis and P. murcianum pigment was evaluated on mammalian cell lines HEK293 and NIH/3T3. Results showed that variations on initial pH, NaCl and peptone, resulted in increments up to 188.2% for red pigment of T. australis and 107.4% for yellow pigment of P. murcianum, regarding non-optimized conditions. Tested fungi also showed great differences in culture conditions for the maximum pigment production, with P. murcianum requiring an alkaline medium (initial pH 9) supplemented with NaCl and T. australis an acidic medium (initial pH 5) without addition of salt. The cytotoxicity assays provided evidences on the safe nature of these natural pigments when used for textile applications. The cytotoxicity assay showed that the threshold of toxicity, given by the lowest IC₅₀ value (0.21 g L⁻¹) was more than double of the concentration of pigment required to dye the wool samples. In addition, cytotoxicity of lixiviates depicted no toxic effect over tested cells.

Terfezia claveryi Chatin was the first desert truffle species to be cultivated, the mycorrhizal plants being successfully produced by using both desert truffle spores and mycelia. However, it is more advisable to use mycelium than spores whenever possible and profitable. Given the low yields of mycelia obtained using traditional culture methods of this truffle, the medium composition was modified in an attempt to determine its nutritional requirements. For this, an assay involving response surface methodology was performed using Box-Behnken design to find the optimal parameters for the high production of mycelial biomass. The best results were obtained with glucose as carbon source, buffering the pH at 5 during culture, adding a pool of vitamins, and adjusting the optimal concentrations of carbon and nitrogen sources of the MMN medium. Biomass production increased from 0.3 to 3 g L⁻¹ dry weight and productivity increased from 10.7 to 95.8 mg L⁻¹ day⁻¹ dry weight. The produced mycelium was able to colonize Helianthemum roots efficiently, providing more than 50% ectomycorrhizal colonization.