EFECTO DE BORDE EN LA DIVERSIDAD Y COLONIZACIÓN DE ECTOMICORRIZAS DE Quercus humboldtii (FAGACEAE) EN ARCABUCO- BOYACÁ-COLOMBIA / Edge effect on the diversity and colonization of ectomycorrhizae of Quercus humboldtii. (FAGACEAE) in Arcabuco- Boyacá-Colombia

RESUMEN Los robledales en Colombia están dominados por la especie Quercus humboldtii Bonpl. Esta especie se encuentra en categoría de vulnerable debido a la deforestación para generar cultivos, zonas ganaderas y plantaciones de especies exóticas, ocasionando la formación de bordes por el deterioro del ecosistema. Estos bosques establecen asociaciones simbióticas con especies de hongos ectomicorrícicos, permitiendo el intercambio de nutrientes entre las hifas de los hongos y las raíces de las plantas. Este estudio analiza el efecto de borde en un área al interior (BNI-C) y al borde de un bosque de roble no intervenido (BNI-B), además de dos bordes de bosque con intervención antropogénica, una en contacto con plantación de Eucalyptus sp. (BE) y otro con ganadería (BG). Se estableció el borde de bosque mediante variables ambientales (temperatura ambiente, luminosidad temperatura y humedad del suelo). Se colectaron raicillas de siete árboles tanto de interior como de borde para medir la colonización y caracterizar morfológicamente las ectomicorrizas asociadas a las raíces de roble. Se evidenció el efecto de borde en el grado de colonización ectomicorrícica en las raíces de Q. humboldtii con porcentajes de 18 a 30 % en BNI, 15 % en BE y 47 % en BG. Los géneros ectomicorrícicos Cenococcum sp. y Lactarius sp. presentaron la mayor abundancia en los tres bosques, variando considerablemente cerca a los bordes en BG y BE. Se evidenciaron cambios de porcentaje de colonización y diversidad de morfotipos de ectomicorrizas en los bordes de los dos bosques intervenidos .

ABSTRACT The oak forests in Colombia are dominated by the species Quercus humboldtii Bonpl. which is in the vulnerable category due to deforestation to generate crops, livestock areas and plantations of exotic species, causing the formation of edges due to the deterioration of the ecosystem. These forests establish symbiotic associations with species of ectomycorrhizal fungi, allowing the exchange of nutrients and water between fungal hyphae and plant roots. This study analyzes the edge effect in the interior (BNI-C) and at the edge of an undisturbed oak forest (BNI-B), in addition to two forest edges with anthropogenic intervention, one in contact with a plantation of Eucalyptus sp. (BE) and another with cattle ranching (BG). The forest edge was established by measuring environmental variables (ambient temperature, luminosity, temperature, and soil humidity). Oak roots were collected from seven trees at the interior and edge of each forest and the quantification of colonization and morphological characterization of ectomycorrhizae was made. The edge effect was evidenced in the degree of ectomycorrhizal colonization in the roots of Q. humboldtii with percentages of 18 to 30 % in BNI, 15 % in BE and 47 % in BG. The ectomycorrhizal genera Cenococcum sp. and Lactarius sp. showed the highest abundance in the three forests, varying considerably near the edges in BG and BE. Changes in the percentage of colonization and morphotype diversity of ectomycorrhizae were evidenced at the forest edge in contact with the two disturbed areas.

Wild Edible Mushrooms Depict a Dissimilar Biogeographical Distribution in Humid Forests of Cameroon

For millennia, wild edible mushrooms (WEM) had always been considered as substantial food and medicinal sources, for local communities, both Bantu and indigenous peoples. However, few information and sparse data are available on useful mushrooms of Cameroon. A study was undertaken to update the checklist of WEM in humid forests of Cameroon. From mushroom excursions, surveys and inventories, thousand fungal specimens were collected in situ, described and identified using key features and references. Wild edible mushrooms were recruited in three trophic groups. They denoted a dissimilar national biogeographical distribution. Saprophytes and Termitomyces were encountered throughout the country; ectomycorrhizal mushrooms occurred in forest clumps, only in three regions: South, Southeast and Southwest. 117 WEM were listed belonging to 17 families and 43 genera, including nearly 22 Termitomyces, 32 ectomycorrhizal and 63 saprophyte species. 15 WEM were also claimed to have medicinal properties. This vast mushroom diversity related to various specific habitats and ecological niches. Five fungal groups were considered as excellent edible. Amanita and Boletus species were seldom consumed. Most mushroom species were harvested solely for home consumption, with the exception of Termitomyces, the only marketed mushroom. In fine, the diversity of WEM was high but poorly known and valorized. To fulfill the Nagoya convention, it is recommended to pursue mycological inventory of macrofungi in Cameroon, including the use of molecular tools and to cultivate local wild edible saprophyte mushrooms.

Tuber borchii Shapes the Ectomycorrhizosphere Microbial Communities of Corylus avellana

In this study, eight-month-old ectomycorrhizae of Tuber borchii with Corylus avellana were synthesized to explore the influence of T. borchii colonization on the soil properties and the microbial communities associated with C. avellana during the early symbiotic stage. The results showed that the bacterial richness and diversity in the ectomycorrhizae were significantly higher than those in the control roots, whereas the fungal diversity was not changed in response to T. borchii colonization. Tuber was the dominant taxon (82.97%) in ectomycorrhizae. Some pathogenic fungi, including Ilyonectria and Podospora, and other competitive mycorrhizal fungi, such as Hymenochaete, had significantly lower abundance in the T. borchii inoculation treatment. It was found that the ectomycorrhizae of C. avellana contained some more abundant bacterial genera (e.g., Rhizobium, Pedomicrobium, Ilumatobacter, Streptomyces, and Geobacillus) and fungal genera (e.g., Trechispora and Humicola) than the control roots. The properties of rhizosphere soils were also changed by T. borchii colonization, like available nitrogen, available phosphorus and exchangeable magnesium, which indicated a feedback effect of mycorrhizal synthesis on soil properties. Overall, this work highlighted the interactions between the symbionts and the microbes present in the host, which shed light on our understanding of the ecological functions of T. borchii and facilitate its commercial cultivation.

Observation and Distribution of Ectomycorrhizal Fungi in Pinus Roots

Detailed structures of ectomycorrhizae formed in Pinus roots were observed with various microscopes: light, fluorescence, and scanning electron microscopes. The mantles and Hartig nets commonly found in the structure of ectomycorrhiza were newly observed according to developmental stage by various staining. The mycelia were observed to be composed of coiled types on the surface of epidermal root during early stage and fused to form mantles of smooth fungal layers, loosing mycelia with some viscous liquid secreted. The ectomycorrhizal hyphae in anatomical roots penetrated the cortical layer and formed obviously mantle and Hartig net. The round spots of ectomycorrhizal mycelia were observed morphological distribution from the cortical layer to vascular bundle of stele in the ectomycorrhizal roots of Pinus species and especially scattered at the area of meristem at the root tip as longitudinal sections. Those mycelia penetrated seemed to move into other roots by means of vascular bundle of ectomycorrhizal roots and newly form ectomycorrhizal roots of dichotomous branches.

Ectomycorrhizal Roots Collected from the Bases of the four Edible Basidiocarps Around Mt. Wol Ak

The ectomycorrhizal roots were collected from the soils around the bases of basidiocarps of the four edible mushrooms in the stands of Pinus densiflora or Querus acutissima communities (Mt. Wol-Ak in Eastern Chung-Puk): The basidiocarps of Tricholoma matsutake (TM), Sarcodon asparatus (SA), S. imbricatum (SI), and Polyozellus multiplex (PM) are usually collected. The ectomycorrhizal roots of TM, PM and SI were related to the roots of P. densiflora, but the other to the roots of Q. acutissima in Korea. Particularly, the basidiocarps of PM were collected in the mixed stand of both P. densiflora and Q. acutissima. The morphologies of the ectomycorrhizal roots were observed to be the yellowish brown coral (dichromatous) or pyramid types in the roots of the pine, but dark brown un-branched sticks (roots) in the ends of ectomycorrhizal roots of Querus plants. The un-branched roots were covered with the dark mycelia (rhizomorph) around them. Therefore, the ectomyorrhizal roots of PM were observed to have two kinds of types; The single blackish un-branched roots were observed to be attached to the yellowish coral type roots. The bundles of TM mycelia were filled with cortical cells (in the roots of P. densiflora), but the mycelia of the other fungi (Aphylloporales) were massed between the cortical cells of P. densiflora or Q. acutissima. Their anatomical and gross features were considered to be simailar but very important in the ectomycorrhizal roots for these edible mushrooms.