Micorrizas arbusculares

Las micorrizas son asociaciones simbióticas mutualistas de diversos tipos que se establecen entre ciertos hongos del suelo y las raíces de una planta. De entre estas asociaciones destacan por su ubicuidad las endomicorrizas o micorrizas arbusculares, aparentemente las más comunes en la naturaleza, ya que ocurren en la mayoría de los suelos y en el 90% de las familias de plantas de la tierra. La ubicación taxonómica de los hongo sendomicorrízicos ha evolucionado recientemente a partir de consideraciones basadas en la revisión de esporas fósiles, las relaciones entre las diferentes categorías de los hongos actuales, su morfología y su comportamiento fisiológico. La importancia de las endomicorrizas ha aumentado en la última década debido a numerosos reportes de efectos benéficos sobre las plantas, que van desde incrementos en la absorción de nutrimentos en el suelo, su influencia sobre las relaciones hídricas y la protección contra agentes patógenos, hasta el importante papel ecológico que estas asociaciones parecen jugar en la sucesión de especies en las comunidades vegetales naturales

The impact of domestication and crop improvement on arbuscular mycorrhizal symbiosis in cereals: insights from genetics and genomics

The cereals (rice, maize, wheat, sorghum and the millets) provide over 50% of the world’s caloric intake, a value that rises to >80% in developing countries. Since domestication, cereals have been under artificial selection, largely directed towards higher yield. Throughout this process, cereals have maintained their capacity to interact with arbuscular mycorrhizal (AM) fungi, beneficial symbionts that associate with the roots of most terrestrial plants. It has been hypothesized that the shift from the wild to cultivation, and above all the last ~50 years of intensive breeding for high-input farming systems, has reduced the capacity of the major cereal crops to gain full benefit from AM interactions. Recent studies have shed further light on the molecular basis of establishment and functioning of AM symbiosis in cereals, providing insight into where the breeding process might have had an impact. Classic phytohormones, targets of artificial selection during the generation of Green Revolution semi-dwarf varieties, have emerged to be important regulators of AM symbiosis. Although there is still much to be learned about the mechanistic basis of variation in symbiotic outcome, these advances are providing an insight into the role of arbuscular mycorrhiza in agronomic systems

Assessing vegetable oils and extracts for the control of Sitophilus zeamaiz and its impact on the seed quality of corn

Sitophilus zeamaiz es una de las especies de gorgojos que más pérdidas causa en granos almacenados en el mundo; su control se basa principalmente en productos sintéticos, que con el paso del tiempo resultan menos efectivos. En la presente investigación se evaluaron aceites vegetales de ricino, soya y extractos vegetales de neem y lila sobre poblaciones de S. zeamaiz y sus efectos sobre la germinación y parámetros fisiológicos de las plántulas. Los resultados muestran que el aceite de soya dio los mejores resultados de control, al presentar mortalidades entre un 92 y 100% a las 192 horas. Sin embargo, este aceite afecta la germinación a dosis de 2000 a 10000 ppm. El extracto de neem presentó mortalidades del 78,75 y 91,25% a las 192 horas, sin afectar la germinación ni las propiedades agronómicas. Finalmente, el aceite de ricino y el extracto de lila fueron los tratamientos que, para las condiciones del presente estudio, no mostraron altas mortalidades sobre S. zeamaiz.Sitophilus zeamaiz is one of the most damaging weevil species of stored grains in the world and a major cause of devastating losses. Its control is mainly based on synthetic products that are every day less effective. The current research work assessed the effects of castor oil, soybean oil; Neem and lily plant extracts on S. zeamaiz populations and their impact upon germination and physiological parameters of seedlings. Results have shown that soybean oil yielded the best control results, with mortality rates between 92 and 100% after 192 hours of the application. Nevertheless, soybean oil affects germination at 2000 - 10000 ppm rates. Neem extract reached mortality rates of 78.75 and 91.25% at 192 hours, with no impact on germination and agronomic properties. Finally, castor oil and lily extract did not yield high mortality rates over S. zeamaiz.Fil: Cerna Chávez, Ernesto. Universidad Autónoma Agraria Antonio Narro (México). Departamento de Parasitología AgrícolaFil: Landeros Flores, Jerónimo. Universidad Autónoma Agraria Antonio Narro (México). Departamento de Parasitología AgrícolaFil: Ochoa Fuentes, Yisa María. Universidad Autónoma de Aguascalientes (México). Centro de Ciencias AgropecuariasFil: Guevara Acevedo, Luis. Universidad Autónoma Agraria Antonio Narro (México). Departamento de Parasitología AgrícolaFil: Badii Zabeth, Mohammad H.. Universidad Autónoma de Nuevo León (México). Facultad de Ciencias BiológicasFil: Olalde Portugal, Víctor. Instituto Politécnico Nacional (México). Centro de Investigación y de Estudios Avanzados. Laboratorio de Bioquímica Ecológic

The genetic architecture of host response reveals the importance of arbuscular mycorrhizae to maize cultivation.

Arbuscular mycorrhizal fungi (AMF) are ubiquitous in cultivated soils, forming symbiotic relationships with the roots of major crop species. Studies in controlled conditions have demonstrated the potential of AMF to enhance the growth of host plants. However, it is difficult to estimate the actual benefit in the field, not least because of the lack of suitable AMF-free controls. Here we implement a novel strategy using the selective incorporation of AMF-resistance into a genetic mapping population to evaluate maize response to AMF. We found AMF to account for about one-third of the grain production in a medium input field, as well as to affect the relative performance of different plant genotypes. Characterization of the genetic architecture of the host response indicated a trade-off between mycorrhizal dependence and benefit. We identified several QTL linked to host benefit, supporting the feasibility of breeding crops to maximize profit from symbiosis with AMF

Influencia del gatuño (Mimosa monancistra benth.) en la infiltración de agua y la cantidad de forraje en pastizales con diferente grado de disturbio en el altiplano central mexicano

Observations were made during 2002 and 2004 in the states of Aguascalientes and Jalisco, México, aiming at evaluating catclaw mimosa´s influence on the amount of herbaceous biomass, total water infiltration and infiltration depth in the soil profile, on three sites and two influence areas (inside and outside) catclaw mimosa´s canopies. The amount of herbaceous biomass in site I was different 264.7 g/m2 and 186.5 g/m2 obtained inside and outside catclaw mimosa´s canopies respectively, as influenced by the interaction site X influence area (PLas observaciones se realizaron en el periodo comprendido entre el año 2002 y el 2004 en los estados de Aguascalientes y Jalisco, México, con los objetivos de evaluar la influencia del gatuño en la cantidad de biomasa herbácea, la infiltración total de agua y la profundidad de infiltración en el perfil del suelo, en tres sitios y dos áreas de influencia (dentro y fuera) del dosel de gatuño. La cantidad de biomasa en el sitio I resultó diferente (

Reproduction of Oncidium poikilostalix (Orchidaceae), potentially invading coffee plantations in Soconusco, Chiapas, México

Context – Oncidium poikilostalix (Kraenzl.) M.W.Chase & N.H.Williams (Orchidaceae) was first reported in Mexico in 2008 and grows on coffee bushes in shaded plantations in Soconusco region in southeast Mexico. Goal – To study the reproductive characteristics and the endophytic fungi with which this orchid is associated to evaluate current conservation status, its possible influence on other epiphytic orchids sharing the same coffee agroecosystem and identify the morphological and adaptive response that have permitted successful colonization of this human landscape. Methods – We determined flower production and percent fruit set, percent loss of seeds due to mechanical or biological damage and total seed rain in two populations, during two years (2008–2009). We characterized morphologically the seed of O. poikilostalix and isolated the fungi associated with its roots. Results – Rapid growth and development of the populations were observed at various levels: recruitment and survival levels were high, with many more adult plants and flowers found in both populations in the second year. Combined percent pollination rose from 1.82% in 2008 to 3.37% in 2009, resulting in the production of 3,387,468 seeds in 2008, rising to 10,001,096 in 2009. We isolated and identified to genus level, thirteen taxa of fungi, including various strains of Rhizoctonia sp. Conclusions – O. poikilostalix interacts with a variety of mycorrhizal symbionts in new habitats. O. poikilostalix is a vigorous and weedy species which should be monitored to prevent it from displacing native, rare and slower growing species, such as Oncidium guatemalenoides M.W.Chase & N.H.Williams, growing in coffee plantations in southeast México

Reproduction of Oncidium poikilostalix (Orchidaceae), potentially invading coffee plantations in Soconusco, Chiapas, México

Context – Oncidium poikilostalix (Kraenzl.) M.W.Chase & N.H.Williams (Orchidaceae) was first reported in Mexico in 2008 and grows on coffee bushes in shaded plantations in Soconusco region in southeast Mexico. Goal – To study the reproductive characteristics and the endophytic fungi with which this orchid is associated to evaluate current conservation status, its possible influence on other epiphytic orchids sharing the same coffee agroecosystem and identify the morphological and adaptive response that have permitted successful colonization of this human landscape. Methods – We determined flower production and percent fruit set, percent loss of seeds due to mechanical or biological damage and total seed rain in two populations, during two years (2008–2009). We characterized morphologically the seed of O. poikilostalix and isolated the fungi associated with its roots. Results – Rapid growth and development of the populations were observed at various levels: recruitment and survival levels were high, with many more adult plants and flowers found in both populations in the second year. Combined percent pollination rose from 1.82% in 2008 to 3.37% in 2009, resulting in the production of 3,387,468 seeds in 2008, rising to 10,001,096 in 2009. We isolated and identified to genus level, thirteen taxa of fungi, including various strains of Rhizoctonia sp. Conclusions – O. poikilostalix interacts with a variety of mycorrhizal symbionts in new habitats. O. poikilostalix is a vigorous and weedy species which should be monitored to prevent it from displacing native, rare and slower growing species, such as Oncidium guatemalenoides M.W.Chase & N.H.Williams, growing in coffee plantations in southeast México

Expression of phenazine biosynthetic genes during the arbuscular mycorrhizal symbiosis of Glomus intraradices

To explore the molecular mechanisms that prevail during the establishment of the arbuscular mycorrhiza symbiosis involving the genus Glomus, we transcriptionally analysed spores of Glomus intraradices BE3 during early hyphal growth. Among 458 transcripts initially identified as being expressed at presymbiotic stages, 20% of sequences had homology to previously characterized eukaryotic genes, 30% were homologous to fungal coding sequences, and 9% showed homology to previously characterized bacterial genes. Among them, GintPbr1a encodes a homolog to Phenazine Biosynthesis Regulator (Pbr) of Burkholderia cenocepacia, an pleiotropic regulatory protein that activates phenazine production through transcriptional activation of the protein D isochorismatase biosynthetic enzyme phzD (Ramos et al., 2010). Whereas GintPbr1a is expressed during the presymbiotic phase, the G. intraradices BE3 homolog of phzD (BGintphzD) is transcriptionally active at the time of the establishment of the arbuscular mycorrhizal symbiosis. DNA from isolated bacterial cultures found in spores of G. intraradices BE3 confirmed that both BGintPbr1a and BGintphzD are present in the genome of its potential endosymbionts. Taken together, our results indicate that spores of G. intraradices BE3 express bacterial phenazine biosynthetic genes at the onset of the fungal-plant symbiotic interaction

Micorrizas arbusculares

Las micorrizas son asociaciones simbióticas mutualistas de diversos tipos que se establecen entre ciertos hongos del suelo y las raíces de una planta. De entre estas asociaciones destacan por su ubicuidad las endomicorrizas o micorrizas arbusculares, aparentemente las más comunes en la naturaleza, ya que ocurren en la mayoría de los suelos y en el 90% de las familias de plantas de la tierra. La ubicación taxonómica de los hongo sendomicorrízicos ha evolucionado recientemente a partir de consideraciones basadas en la revisión de esporas fósiles, las relaciones entre las diferentes categorías de los hongos actuales, su morfología y su comportamiento fisiológico. La importancia de las endomicorrizas ha aumentado en la última década debido a numerosos reportes de efectos benéficos sobre las plantas, que van desde incrementos en la absorción de nutrimentos en el suelo, su influencia sobre las relaciones hídricas y la protección contra agentes patógenos, hasta el importante papel ecológico que estas asociaciones parecen jugar en la sucesión de especies en las comunidades vegetales naturales