Resumen. Se aislaron especies de Mortierella enAgar Dextrosa Papa y agar V8, así como peras maduras y hojas de azalea, como sustratos trampa. Se obtuvieron 419 aislados de Mortierella, de muestras de suelo en Chihuahua, México, los cuales se clasificaron en 21 grupos de acuerdo con sus caracteres morfológicos. Mortierella se aisló con mayor Palabras clave: Mortierellales, diversidad, sustratos trampa, medio de aislamiento, patogenicidad. Morphological and molecular identification ofSe estima que solo un 5% de las especies fún-gicas existentes han sido registradas y descritas (Hawksworth, 2001). Mortierelliales es uno de los órdenes más abundantes y diversos de los hongos basales y hay cerca de 100 especies descritas en 13 géneros de la familia Mortierellaceae (Yadav et al., 2014), género al cual corresponde el hongo Mortierella. La mayoría de las especies de este género producen ácidos grasos poliinsaturados (PUFA) al convertir el exceso de azúcares y otras fuentes de carbón en lípidos bajo diferentes condiciones de fermentación (Rayaroth et al., 2016). En varios estudios se ha demostrado que algunas especies de Mortierella pueden acumular ácidos araquidónico, gamma-linolénico, eicosapentaenoico y docosahexaenoico en el micelio (Ho et al., apple rootstocks under greenhouse conditions and none was pathogenic. These species have not been reported previously in Mexico. The study showed that there are Mortierella species in the rhizosphere of apple trees in Chihuahua Mexico. These fungal isolates might produce polyunsaturated fatty acids and exert effects of elicitation in horticultural plants and fruit trees improving their resistance to multiple pathogens.Key words: Mortierellales, diversity, substrate baits, isolation medium, pathogenicity.It has been estimated that only 5% of the existing fungi species have been recorded and described (Hawksworth, 2001). The Mortierellales is one of the most abundant and diverse orders of basal fungi, with nearly 100 species described into 13 genera of the Mortierellaceae family (Yadav et al., 2014), in which the Mortierella genus is located. Most of species of this genus are able to produce polyunsaturated fatty acids (PUFAs) by converting excess of sugars and other carbon sources into lipids under different fermentation conditions (Rayaroth et al., 2016). Several studies have shown that some Mortierella species are able to accumulate arachidonic, γ-linolenic, eicosapentaenoic and docosahexaenoic acids in the mycelium (Ho et al., 2007; Dedyukhina et al., 2014). These compounds are involved in induction of resistance to phytopathogens in plants of agricultural importance (Zlotek and Wojcik, 2014). Additionally, these PUFAs are widely used as food supplements and drugs to improve the immune response in humans, giving technological importance to the Mortierella genus as an alternative source of these compounds (Dedyukhina et al., 2014). However, existing information about the diversity of Mortierellales is limited or out of date. The identification of Publicación en línea, en...

Streptomyces are recognized as antipathogenic agents and plant-growth-promoting rhizobacteria. The objective of this study was to evaluate the capacities of four antifungal Streptomyces strains to: produce the substances that are involved in plant growth; solubilize phosphates; and fix nitrogen. The effects of the volatile organic compounds (VOCs) that are emitted by these strains on the growth promotion of Arabidopsis thaliana and Phaseolus vulgaris L. (var. Pinto Saltillo) seedlings were also tested. All of the Streptomyces strains produced indole-3-acetic acid (IAA) (10.0 mg/L to 77.5 mg/L) and solubilized phosphates, but they did not fix nitrogen. In vitro assays showed that the VOCs from Streptomyces increased the shoot fresh weights (89–399%) and the root fresh weights (94–300%) in A. thaliana seedlings; however, these effects were less evident in P. vulgaris. In situ experiments showed that all the Streptomyces strains increased the shoot fresh weight (11.64–43.92%), the shoot length (11.39–29.01%), the root fresh weight (80.11–140.90%), the root length (40.06–59.01%), the hypocotyl diameter (up to 6.35%), and the chlorophyll content (up to 10.0%) in P. vulgaris seedlings. 3-Methyl-2-butanol had the highest effect among the ten pure VOCs on the growth promotion of A. thaliana seedlings. The tested Streptomyces strains favored biomass accumulation in A. thaliana and P. vulgaris seedlings.