Carbon-sensitive pedotransfer functions for plant available water

Currently accepted pedotransfer functions show negligible effect of management-induced changes to soil organic carbon (SOC) on plant available water holding capacity (θAWHC), while some studies show the ability to substantially increase θAWHC through management. The Soil Health Institute\u27s North America Project to Evaluate Soil Health Measurements measured water content at field capacity using intact soil cores across 124 long-term research sites that contained increases in SOC as a result of management treatments such as reduced tillage and cover cropping. Pedotransfer functions were created for volumetric water content at field capacity (θFC) and permanent wilting point (θPWP). New pedotransfer functions had predictions of θAWHC that were similarly accurate compared with Saxton and Rawls when tested on samples from the National Soil Characterization database. Further, the new pedotransfer functions showed substantial effects of soil calcareousness and SOC on θAWHC. For an increase in SOC of 10 g kg–1 (1%) in noncalcareous soils, an average increase in θAWHC of 3.0 mm 100 mm–1 soil (0.03 m3 m–3) on average across all soil texture classes was found. This SOC related increase in θAWHC is about double previous estimates. Calcareous soils had an increase in θAWHC of 1.2 mm 100 mm–1 soil associated with a 10 g kg–1 increase in SOC, across all soil texture classes. New equations can aid in quantifying benefits of soil management practices that increase SOC and can be used to model the effect of changes in management on drought resilience

Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity

Carbon-sensitive pedotransfer functions for plant available water

Currently accepted pedotransfer functions show negligible effect of management-induced changes to soil organic carbon (SOC) on plant available water holding capacity (θAWHC), while some studies show the ability to substantially increase θAWHC through management. The Soil Health Institute\u27s North America Project to Evaluate Soil Health Measurements measured water content at field capacity using intact soil cores across 124 long-term research sites that contained increases in SOC as a result of management treatments such as reduced tillage and cover cropping. Pedotransfer functions were created for volumetric water content at field capacity (θFC) and permanent wilting point (θPWP). New pedotransfer functions had predictions of θAWHC that were similarly accurate compared with Saxton and Rawls when tested on samples from the National Soil Characterization database. Further, the new pedotransfer functions showed substantial effects of soil calcareousness and SOC on θAWHC. For an increase in SOC of 10 g kg–1 (1%) in noncalcareous soils, an average increase in θAWHC of 3.0 mm 100 mm–1 soil (0.03 m3 m–3) on average across all soil texture classes was found. This SOC related increase in θAWHC is about double previous estimates. Calcareous soils had an increase in θAWHC of 1.2 mm 100 mm–1 soil associated with a 10 g kg–1 increase in SOC, across all soil texture classes. New equations can aid in quantifying benefits of soil management practices that increase SOC and can be used to model the effect of changes in management on drought resilience

Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity

Diversidad genética en el patosistema maíz-fusarium en el Altiplano de México.

Las variantes de maíz (Zea mays L.) nativas (criollos) preservadas por los agricultores a través de generaciones, constituyen más de 80% del área sembrada con maíz en México; la pudrición de mazorca por Fusarium spp. provoca pérdidas de hasta 30%. El estudio de las poblaciones de maíz y sus patógenos como patosistema tiene sentido, pues en la variación genética del maíz nativo se puede encontrar resistencia/tolerancia a enfermedades; el conocimiento de la estructura de las poblaciones de maíz y del patógeno de manera integral ayudaría a resolver el problema de pudrición, aumentar la producción de grano y conservar la diversidad del maíz. En 2010 se colectaron 56 poblaciones de maíz nativo con y sin síntomas de pudrición de mazorca en cinco estados en México en altitudes entre 1498 y 2520 m. En 2010 y 2011, se evaluó la respuesta de las poblaciones de maíz, en tres localidades (Montecillo y Ayapango, Edo. de Méx., y Huamelulpan, Oax.) bajo infección natural de Fusarium spp. y condiciones de temporal. En 2012 se realizó una evaluación en plántula para valorar la virulencia del patógeno y la susceptibilidad/tolerancia de las poblaciones de maíz ante Fusarium spp de distinta procedencia geográfica. En 2013 un análisis isoenzimático para poblaciones de maíz y poblaciones de Fusarium fue necesario para valorar la diversidad genética en el patosistema. La respuesta en campo, mostró diferencias significativas entre las poblaciones de maíz, entre localidades y para la interacción localidades x población en cada ciclo agrícola; se observó que los maíces locales al ambiente de evaluación tienden a presentar menor daño por Fusarium spp. y mayor rendimiento; por la procedencia geográfica, los maíces de Oaxaca presentaron menor daño que los de los estados de México, Puebla, Tlaxcala y Guerrero. Resultado de la prueba en plántula, se observó variación en virulencia del inóculo, fue más virulento el procedente del estado de México, mientras que el del Edo. de Guerrero provocó menor daño. Las poblaciones de maíz respondieron de manera diferencial, al expresar valores de daño distintos a través de los diferentes inóculos a los que fueron sometidos. Las poblaciones de maíz y las de Fusarium spp. mostraron un patrón de agrupación de acuerdo a su procedencia geográfica. La variación observada en el patosistema Maíz- Fusarium spp. por medio del análisis isoenzimático, puede estar relacionada con la variación ecológica en la zona de exploración, localizada entre los 1490 y 2720 msnm, la cual provee amplia variación ecológica, generando diversidad en ambos organismos. Se obtuvieron evidencias experimentales de que los patrones de virulencia de Fusarium y la respuesta del maíz parecen corresponder a la procedencia geográfica (condiciones ecológicas), lo que sugiere la necesidad de profundizar en el estudio de procesos de coevolución. _______________ GENETIC DIVERSITY IN THE MAIZE-Fusarium PATHOSYSTEM IN THE HIGHLANDS OF MEXICO. ABSTRACT: The native (creole) varieties of maize (Zea mays L. ) preserved by farmers through generations, constitute more than 80% of the area planted with maize in Mexico; the Fusarium spp. ear rot could cause yield losses up to 30 %. The study of maize populations and their pathogens as pathosystem makes sense, because in the genetic variation of native maize can be found resistance/tolerance to such disease; the knowledge of the maize and the pathogen structure populations could help to solve the rot problem, increase the grain production and preserve the genetic diversity. In 2010, 56 native maize populations were collected, with and without symptoms of ear rot from five states in Mexico at altitudes between 1498 and 2520 m. In 2010 and 2011, under rainfed conditions and natural infection by Fusarium, the response of maize populations was evaluated in three locations (Montecillo and Ayapango, Edo. de Mex., and Huamelulpan, Oax.). In 2012, the virulence of the pathogen and the susceptibility/tolerance of maize populations to Fusarium spp. of different geographical origin were assessed in seedling stage. In 2013 an isoenzymatic analysis for maize populations and Fusarium populations were required in order to know the genetic diversity in the pathosystem. The field response, showed significant differences between maize populations, between locations and interaction environment x population, was evident that local maize populations in the evaluation environment tend to have less damage by Fusarium spp., and higher grain yield; by geographical origin, maize from Oaxaca should less damage than those from the states of Mexico, Puebla, Tlaxcala and Guerrero. The seedling test showed variation in virulence between sources of inoculum; the most virulent was from the state of Mexico, while the on from Guerrero caused minor damages. Maize populations responded differently, expressing different degree of damage through various sources of inoculum. The maize and Fusarium spp. populations showed a pattern of grouping according to their geographical origin. The variation observed in the maize-Fusarium spp. pathosystem through isoenzyme analysis, may be related to ecological variation in the exploration area, located between 1490 and 2720 m, which provides wide environmental variation, generating diversity in both populations. Experimental evidences were obtained about patterns of Fusarium virulence and maize populations responses that seems correspond with geographical origin (ecological conditions) that may suggest the need of research in order to better insight on coevolution processes.Tesis (Doctorado en Ciencias, especialista en Genética).- Colegio de Postgraduados, 2013.Consejo Nacional de Ciencia y Tecnología (CONACYT)

H-383: híbrido de maíz blanco intermedio para grano y forraje para el norte, centro y occidente de México

In Mexico the demand for maize grain for human consumption and livestock is around 38 million tons; however, only between 25 and 28 million are produced, the rest are imported from the United States. Deficits in maize production are mainly due to the use of inappropriate varieties, poor crop management, and biotic and abiotic problems occurring regularly during the crop cycle. In view of the need for more productive hybrids, the National Institute for Forestry, Agriculture and Livestock Research (INIFAP) in the year 2 000 initiated a genetic improvement program aimed at obtaining hybrids of high yield of grain and forage, from which the hybrid was derived of single cross h-383 white grain formed by the combination of lines PAB7 and PAB8. The line PAB7 was derived from the PGB population and its pedigree is PGB-2-1-3-1-1-N1-3-b-b-b. The PAB8 line corresponds to the sub-tropical public line CML312 of the International Center for Maize and Wheat Improvement (CIMMYT) with three more generations of inbreeding for the selection of greater ear health. The hybrid has a yield potential higher than 15 t ha -1 of irrigated grain, and up to 12 t ha -1 in areas of good weather; produces between 24.7 and 26 t ha -1 dry matter, with values between 71 and 74% in digestibility and between 40 and 48% in fiber digestibility. It has adaptation in areas of irrigation of the North Central region of Mexico and the Bajio; as well as in good weather areas of the Center and West of Mexico, located between 1 600 and 2 000 meters above sea level. It is of intermediate cycle, leaves dark green and height between 3 and 3.2 m. The hybrid was registered in the National Service of Inspection and Certi fication of Seeds (SNICS) with the key: MAZ-1352-190712. Palabras clave: Zea mays L., forage production, forage quality, grain yield, hybrid.En México la demanda de grano de maíz para consumo humano y pecuario es de alrededor de 38 millones de toneladas; sin embargo, solo se producen entre 25 y 28 millones, el resto se importa de Estados Unidos. El déficit en la producción de maíz se debe principalmente al uso de variedades no apropiadas, manejo deficiente del cultivo y a problemas bióticos y abióticos que ocurren regularmente durante el ciclo del cultivo. Ante la necesidad de contar con híbridos más productivos, el Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP) en el año 2 000 se inició un programa de mejoramiento genético orientado a obtener híbridos de alto rendimiento de grano y forraje, del cual se derivó el híbrido de cruza simple H-383 de grano blanco formado por la combinación de las líneas PAB7 y PAB8. La línea PAB7 se derivó de la población PGB y su genealogía es PGB-2-1-3-1-1-N1-3-b-b-b. La línea PAB8, corresponde con la línea pública subtropical CML312 del Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT) con tres generaciones más de endogamia para selección de mayor sanidad de mazorca. El híbrido tiene un potencial de rendimiento superior a la 15 t ha -1 de grano en riego, y hasta 12 t ha -1 en áreas de buen temporal; produce entre 24.7 y 26 t ha -1 de materia seca, con valores entre 71 y 74% en digestibilidad y entre 40 y 48% en digestibilidad de la fibra. Tiene adaptación en áreas de riego de la región Norte Centro de México y El Bajío; así como, en áreas de buen temporal del Centro y Occidente de México, localizadas entre los 1 600 y 2 000 msnm. Es de ciclo intermedio, hojas color verde oscuro y altura entre 3 y 3.2 m. El híbrido se registró en el Servicio Nacional de Inspección y Certi fi cación de Semillas (SNICS) con la clave: MAZ-1352-190712. Palabras clave: Zea mays L., calidad de forraje, híbrido, producción de forraje, producción de grano

Response of native maize from Mexican highlands to ear rot, under natural infection.

El objetivo del presente estudio fue evaluar la respuesta a la infección natural por Fusarium spp. en las mazorcas de 55 poblaciones nativas de maíz. Las poblaciones evaluadas procedían de cinco estados de México, estas se sembraron en tres localidades en 2010 y 2011 bajo condiciones de secano (temporal). El porcentaje promedio de pudrición de mazorca fue significativamente diferente entre las poblaciones de maíz, localidades y poblaciones dentro de cada localidad y entre años. Las agrupaciones de poblaciones por color de grano también mostraron diferencias, ya que los grupos de color amarillo y rojo mostraron el menor porcentaje de infección. Por la procedencia geográfica, los maíces de Oaxaca presentaron menor daño que los de los estados de México, Puebla, Tlaxcala y Guerrero. En rendimiento de grano hubo diferencias entre localidades, poblaciones y años. Los efectos significativos en la interacción de grupos de poblaciones por localidad indican que las poblaciones de maíz de origen local tienden a presentar menor porcentaje de pudrición y mayor rendimiento, lo que sugiere un proceso de coevolución y coadaptación. El mayor rendimiento de mazorca se obtuvo en 2011, en donde también destacaron las poblaciones de Oaxaca, por lo que se infiere que las poblaciones nativas de maíz de esta entidad son una fuente potencial de resistencia/tolerancia a pudrición de mazorca por Fusarium spp.The objective of this study was to evaluate the response to natural infection of Fusarium spp. on 55 native maize populations. The populations evaluated were collected in five states of Mexico, and planted in three locations in 2010 and 2011 under rainfed conditions. The average percentage of ear rot was significantly different among maize populations, locations and among populations within locations and years. The population groups of kernel color showed differences among them, where yellow and red groups presented the lower infection percentages. In the relation to geographic provenance, maize populations of Oaxaca presented less damage than those from Mexico, Puebla, Tlaxcala and Guerrero states. In grain yield, there were differences among locations, populations and years. In the significant interaction between population groups and locations showed that populations with local origin presented low ear rot percentage and major yield, which suggest a coevolution and coadaptation process. The higher ear weight was obtained in 2011, where the Oaxaca populations were outstanding. It is possible to infer that native maize populations from Oaxaca are a potential source of resistance or tolerance to ear rot caused by Fusarium spp

The Antiproliferative Effect of Cyclodipeptides from Pseudomonas aeruginosa PAO1 on HeLa Cells Involves Inhibition of Phosphorylation of Akt and S6k Kinases

Pseudomonas aeruginosa PAO1, a potential pathogen of plants and animals, produces the cyclodipeptides cyclo(l-Pro-l-Tyr), cyclo(l-Pro-l-Phe), and cyclo(l-Pro-l-Val) (PAO1-CDPs), whose effects have been implicated in inhibition of human tumor cell line proliferation. Our purpose was to investigate in depth in the mechanisms of HeLa cell proliferation inhibition by the PAO1-CDPs. The results indicate that PAO1-CDPs, both purified individually and in mixtures, inhibited HeLa cell proliferation by arresting the cell cycle at the G0–G1 transition. The crude PAO1-CDPs mixture promoted cell death in HeLa cells in a dose-dependent manner, showing efficacy similar to that of isolated PAO1-CDPs (LD50 of 60–250 µM) and inducing apoptosis with EC50 between 0.6 and 3.0 µM. Moreover, PAO1-CDPs showed a higher proapoptotic activity (~103–105 fold) than their synthetic analogs did. Subsequently, the PAO1-CDPs affected mitochondrial membrane potential and induced apoptosis by caspase-9-dependent pathway. The mechanism of inhibition of cells proliferation in HeLa cells involves inhibition of phosphorylation of both Akt-S473 and S6k-T389 protein kinases, showing a cyclic behavior of their expression and phosphorylation in a time and concentration-dependent fashion. Taken together our findings indicate that PI3K–Akt–mTOR–S6k signaling pathway blockage is involved in the antiproliferative effect of the PAO1-CDPs