Ronald Ferrera-Cerrato

The use of arbuscular mycorrhizae to control onion white rot (Sclerotium cepivorum Berk.) under field conditions

Abstract A field experiment was carried out to determine the effects of the inoculation of onion (Allium cepa L.) with Glomus sp. Zac-19 on the development of onion white rot (Sclerotium cepivorum Berk.) and on onion production. Mycorrhization delayed onion white rot epidemics by 2 weeks and provided a significant protection against the disease for 11 weeks after onion transplanting, as compared with nonmycorrhizal controls. Mycorrhizal plants showed an increase of 22% in yield, regardless of the presence of the white rot pathogen.

Arbuscular mycorrhizal fungi on growth, nutrient status, and total antioxidant activity of Melilotus albus during phytoremediation of a diesel-contaminated substrate

This research evaluated the effects of arbuscular mycorrhizal fungi (AMF) on growth, nutritional status, total antioxidant activity (AOX), total soluble phenolics content (TPC), and total nitrate reductase activity (NRA) of leaves and roots of Melilotus albus Medik planted in diesel-contaminated sand (7500 mg kg(-1)). Seedlings of Melilotus either Non inoculated (Non-AMF) or pre-inoculated plants (AMF) with the AMF-inoculum Glomus Zac-19 were transplanted to non-contaminated or contaminated sand. After 60 days, diesel significantly reduced plant growth. AMF- plants had no significant greater (64% and 89%, respectively) shoot and leaf dry weight than Non-AMF plants, but AMF plants had lower specific leaf area. AMF-plants had significantly greater content of microelements than non-AMF plants. Regardless diesel contamination, the total AOX and TPC were significantly higher in leaves when compared to roots; in contrast, NRA was higher in roots than leaves. Diesel increased total AOX of leaves, but AMF-plants had significantly lower AOX than non-AMF plants. In contrast, roots of AMF-plants had significantly higher AOX but lower NRA than non-AMF plants. AMF-colonization in roots detected via the fungal alkaline phosphatase activity was significantly reduced by the presence of diesel. AMF-inoculation alleviated diesel toxicity on M. albus by enhancing plant biomass, nutrient content, and AOX activity. In addition, AMF-plants significantly contributed in higher degradation of total petroleum hydrocarbons when compared to non-AMF-plants.

Bioleaching of gold, copper and nickel from waste cellular phone PCBs and computer goldfinger motherboards by two Aspergillus nigerstrains

In an effort to develop alternate techniques to recover metals from waste electrical and electronic equipment (WEEE), this research evaluated the bioleaching efficiency of gold (Au), copper (Cu) and nickel (Ni) by two strains of Aspergillus niger in the presence of gold-plated finger integrated circuits found in computer motherboards (GFICMs) and cellular phone printed circuit boards (PCBs). These three metals were analyzed for their commercial value and their diverse applications in the industry. Au-bioleaching ranged from 42 to 1% for Aspergillus niger strain MXPE6; with the combination of Aspergillus niger MXPE6 + Aspergillus niger MX7, the Au-bioleaching was 87 and 28% for PCBs and GFICMs, respectively. In contrast, the bioleaching of Cu by Aspergillus niger MXPE6 was 24 and 5%; using the combination of both strains, the values were 0.2 and 29% for PCBs and GFICMs, respectively. Fungal Ni-leaching was only found for PCBs, but with no significant differences among treatments. Improvement of the metal recovery efficiency by means of fungal metabolism is also discussed.

Efectividad de siete consorcios nativos de hongos micorrízicos arbusculares en plantas de café en condiciones de invernadero y campo

Se probo el efecto de siete consorcios de hongos micorrizicos arbusculares (HMA) aislados de fincas cafetaleras con diferente nivel de tecnologia (bajo, medio y alto) del estado de Veracruz, en el crecimiento de plantas de cafe (Coffea arabica L.) var. Garnica en condiciones de invernadero y de campo. El grado de tecnificacion influyo en la composicion de especies de HMA, a mayor tecnificacion menor numero de especies de HMA encontradas. En condiciones de invernadero, los consorcios incrementaron la altura en un 91 % con respecto al testigo absoluto y al testigo fertilizado con fosforo (800 mg Ca(PO4)3 L-1). A los 130 dias despues de la inoculacion (DDI), el mejor consorcio fue La Estanzuela (ES). En condiciones de campo, a los 290 DDI, las plantas inoculadas con los consorcios ES, Miradores (MI), y Paso Grande (PG) tuvieron mayor supervivencia (> 80 %). Los consorcios mas efectivos en la promocion de la altura y supervivencia de las plantas en condiciones de campo, procedieron de agroecosistemas con nivel de tecnologia medio (MI y ES), mismos que tuvieron mayor numero de especies de HMA.

Research on arbuscular mycorrhizae in Mexico: an historical synthesis and future prospects

This review analyzes the historical development and advances of the research on arbuscular mycorrhizal fungi (AMF) in Mexico, as well as the prospects for future research. AMF-research has been focused on studying both diversity and functionality in several ecosystems of Mexico, but mainly in the tropical dry and rainy ecosystems, and the agricultural systems. In Mexico, 95 species of AMF have been recorded, representing 41% of the known species worldwide. The functional effects of AMF colonization have been examined in approximately 10% of the known host plants, but greenhouse studies continue to dominate over those conducted under field conditions. Even though research to date has been at the organismic level, further effort is needed due to the high plant diversity in Mexico. Studies on AMF biomass under field conditions and more taxonomic determination are required based on morphological features, biochemical determinations (fatty acids) and molecular tools. In addition, ecophysiological and ecological in situ studies would help in understanding the relationships among AMF, soil fauna, nutrients, and host plants. The contribution of AMF to ecosystemic processes is a priority line of research that requires an integrated approach (inter- and multidisciplinary) in order to define the role of AM symbioses for biogeochemical models. The creation of a Mexican mycorrhizal research network has and will help to identify the main challenges. Generating similar research protocols, and sharing databases and experience will assist mycorrhizologists working under the diverse financial and ecological contexts that is to be found in Mexico and Latin America.

Diversity and Agricultural Applications of Arbuscular Mycorrhizal Fungi in Mexico

The knowledge about the genetic and the functional diversity of Arbuscular Mycorrhizal Fungi (AMF) is an important ecological issue that deserves greater research efforts specially when trying to use them into biotechnological approaches in agriculture, horticulture, forestry and ecological restoration. Genetic diversity of AMF is almost unexplored in Mexico. In turn, the functional diversity of these fungi has been poorly evaluated from some ecological studies. However, based on the beneficial effects on growth promotion and nutrition of plants of agronomic importance, some promising strains and consortia of AMF have been obtained. This work shows the beneficial effects of AMF that were isolated from several regions of the Mexican Republic, and to highlight the need to explore the genetic and the functional diversity of AMF from different ecosystems and agrosystems of Mexico, which is considered not only as one of the most biodiverse countries but also for being a domestication center for several cultivated plants which are important from a cultural and a human nutrition point of view.

Soil Parameters which Affect the Survival of Azospirillum brasilense

The survival of Azospirillum brasilense strains Cd and Sp-245 was evaluated in the rhizosphere of wheat and tomato plants and in 23 plant-free soils of 23 soil types obtained from a wide range of environmental conditions in Israel and Mexico. The survival rate of A. brasilense was analyzed for 15 soil parameters. A. brasilense survived well in all the rhizospheres tested, regardless of soil type, bacterial strain, the origin of the soil, or the amount of rainfall each soil received prior to sampling. In the absence of plants, the general survival characteristics of A. brasilense differed and were related mainly to the geographical origin of the soil and not to prevailing environmental conditions. We propose that: (i) A. brasilense is a rhizosphere colonizer which survives poorly in most soils for prolonged periods, (ii) Some major physical and chemical soil parameters may affect survival of the bacteria in plantless soils.

The Fatty Acid Profile Analysis of Cyperus laxus Used for Phytoremediation of Soils from Aged Oil Spill-Impacted Sites Revealed That This Is a C18:3 Plant Species

The effect of recalcitrant hydrocarbons on the fatty acid profile from leaf, basal corm, and roots of Cyperus laxus plants cultivated in greenhouse phytoremediation systems of soils from aged oil spill-impacted sites containing from 16 to 340 g/Kg total hydrocarbons (THC) was assessed to investigate if this is a C18:3 species and if the hydrocarbon removal during the phytoremediation process has a relationship with the fatty acid profile of this plant. The fatty acid profile was specific to each vegetative organ and was strongly affected by the hydrocarbons level in the impacted sites. Leaf extracts of plants from uncontaminated soil produced palmitic acid (C16), octadecanoic acid (C18:0), unsaturated oleic acids (C18:1-C18:3), and unsaturated eichosanoic (C20:2-C20:3) acids with a noticeable absence of the unsaturated hexadecatrienoic acid (C16:3); this finding demonstrates, for the first time, that C. laxus is a C18:3 plant. In plants from the phytoremediation systems, the total fatty acid contents in the leaf and the corm were negatively affected by the hydrocarbons presence; however, the effect was positive in root. Interestingly, under contaminated conditions, unusual fatty acids such as odd numbered carbons (C15, C17, C21, and C23) and uncommon unsaturated chains (C20:3n6 and C20:4) were produced together with a remarkable quantity of C22:2 and C24:0 chains in the corm and the leaf. These results demonstrate that weathered hydrocarbons may drastically affect the lipidic composition of C. laxus at the fatty acid level, suggesting that this species adjusts the cover lipid composition in its vegetative organs, mainly in roots, in response to the weathered hydrocarbon presence and uptake during the phytoremediation process.

Hongos ectomicorrícicos y la tolerancia a la salinidad en plantas

El proceso de salinizacion de los suelos constituye un problema generalizado a nivel global. En este sentido, los hongos ectomicorricicos tienen una importante participacion en la recuperacion de suelos forestales ya que involucran una serie de mecanismos celulares que pueden contribuir a la tolerancia a la salinidad en plantas que habitan los bosques templados o boreales. La participacion de los hongos ectomicorricicos en la tolerancia a la salinidad involucra la regulacion homeostatica de los iones, la mejora de captacion de agua y la induccion de genes especificos en las raices colonizadas. Los hongos ectomicorricicos pueden estimular la presencia de osmolitos como la prolina, azucares y polioles que contribuyen en la proteccion de las celulas vegetales. Ademas, estos organismos inducen la sintesis de enzimas antioxidantes y glutation que participan en la disminucion de especies reactivas de oxigeno. Esta revision ofrece una descripcion de la participacion de los hongos ectomicorricicos en la tolerancia a la salinidad en plantas.

Aislamiento de consorcios de hongos micorrícicos arbusculares de plantas medicinales y su efecto en el crecimiento de vinca (Catharanthus roseus)

Este trabajo consistio en propagar e identificar hongos micorricicos arbusculares (HMA) recolectados de plantas medicinales (PM) de areas naturales de bosques mixtos, y seleccionar consorcios micorricicos con base en la promocion del crecimiento de vinca Catharanthus roseus (L) G. Don, planta medicinal cuyos alcaloides tienen propiedades antineoplasicas. En la primera fase experimental se recolectaron raices y suelo rizosferico de 13 PM establecidas en campo para evaluar el porcentaje de colonizacion total (PCT) y cuantificar el numero de esporas; ademas, se tomo una parte del suelo para establecer plantas trampa en invernadero durante 10 meses, y posteriormente evaluar el PCT e identificar los principales generos de HMA. Todas las PM en su condicion natural presentaron colonizacion micorricica, observandose cuatro generos de HMA (Glomus, Acaulospora, Gigaspora y Scutellospora), de los cuales Acaulospora y Glomus fueron los predominantes. En la segunda fase experimental se seleccionaron ocho consorcios con base en el PCT (> 40 %) obtenido en las plantas trampa, que correspondieron a las muestras recolectadas de Adiantum capillus-veneris L., Castilleja tenuiflora Benth., Erigeron karvinskianus DC., Pimpinella anisum L., Plantago major L., Ricinus communis L., Rubus fruticosus L. y Rumex mexicanus Meisn. Estos consorcios fueron inoculados en plantulas de C. roseus para evaluar su capacidad de estimular el crecimiento de esta especie en condiciones de invernadero. Despues de 70 dias, a pesar de presentar un solo genero predominante (Glomus), el consorcio aislado de R. mexicanus promovio de manera mas consistente el crecimiento de C. roseus (numero de hojas, area foliar y peso seco foliar) en comparacion con el resto de los consorcios micorricicos.