No abstract

Sampling of agricultural soils from the Mexican northeastern region was performed to detect Trichoderma spp., genetically characterize it, and assess its potential use as a biologic control agent against Macrophomina phaseolina. M. phaseolina is a phytopathogen that attacks over 500 species of cultivated plants and causes heavy losses in the regional sorghum crop. Sampling was performed immediately after sorghum or corn harvest in an area that was approximately 170 km from the Mexico-USA border. Sixteen isolates were obtained in total. Using colony morphology and sequencing the internal transcribed spacers (ITS) 1 and 4 of 18S rDNA, 14 strains were identified as Trichoderma harzianum, T. koningiopsis and T. virens. Subsequently, their antagonistic activity against M. phaseolina was evaluated in vitro, and 11 isolates showed antagonism by competition and stopped M. phaseolina growth. In 4 of these isolates, the antibiosis phenomenon was observed through the formation of an intermediate band without growth between colonies. One strain, HTE808, was identified as Trichoderma koningiopsis and grew rapidly; when it came into contact with the M. phaseolina colony, it continued to grow and sporulated until it covered the entire petri dish. Microscopic examination confirmed that it has a high level of hyperparasitism and is thus considered to have high potential for use in the control of this phytopathogen.

Caracterización morfológica y molecular de las variedades locales de frijol común cultivado enel altiplano mexicano semi-árido. El objetivo de este trabajo fue caracterizar el frijol común de parcelasagrícolas cultivadas con variedades criollas de frijol común de la región semiárida del altiplano mexicanoutilizando datos morfológicos y de Polimorfismos en la Longitud de los Fragmentos Amplificados (AFLPs). Las características morfológicas fueron discriminantes y mostraron la agrupación de las 150 accesiones en función del origen geográfico y el color de la testa de la semilla. La combinación deiniciadores AFLP (amplified fragment length polymorphism) mostraron un rango polimórfico entre 0,292(EM-ACT AGG +) y 0,375 (M + E-ACA-AGA). La frecuencia y distribución de los fragmentos polimórficos permitió la detección de un mayor número de fragmentos raros en las accesiones 121 y 111 (Flor deMayo y frijol común Negro, respectivamente). El análisis de las relaciones genéticas, varianza molecular(AMOVA), y el índice de diversidad de Powell confirmaron amplia base genética del germoplasma defrijol común del altiplano semi-árido mexicano. El análisis de coordenadas principales y de agrupacióndemostraron fuerte relación genética entre las variedades colectadas con base a la similitud en el nombre de la variedad, el origen y el color de la testa de la semilla, lo que demuestra la influencia de las diferentes prácticas de cultivo en las dos regiones y la adaptación de P. vulgaris a las condiciones agroclimáticas dela región semiárida del altiplano mexicano.

In Mexico there is an important production of soybeans; however, no evidence of the analysis of organoleptic attributes in Mexican soybean products was found, so the objective of this work was to sensorially characterise soymilk made from commercial beans grown in northern Mexico based on seven organoleptic attributes. A panel of trained judges evaluated 11 soymilks made from commercial soybeans grown in Mexico, two soymilks made from commercial soybeans reported to be free of lipoxygenases, and one control soymilk. Evaluated flavour attributes were beany, milky, greasy, toasted, bitter, metallic and rancid. The results showed that the soymilks from the JP 30790 and JP 28955 genotypes generated low beany notes. The Mexican variety Guayparime S-10 obtained the lowest beany flavour note. Among Mexican soybeans, the soymilks of Huasteca 700 and Vernal varieties got the highest values of the milky flavour and the JP 30790 and JP 28955 materials obtained intermediate values in this attribute; in the rancid attribute, the zero value was given to all the soymilks. The scarce beany notes and the high milky attribute, as well as the zero value in the rancid attribute favour an acceptable flavour in the soymilks.