Abstract This study consisted of determining the effect of Bacillus strains inoculated alone or in combination with phytopathogenic fungi on the production of human health-related compounds and volatile organic compounds (VOCs) in tomato fruits. Seedlings were cultivated under greenhouse conditions and inoculated with B. amyloliquefaciens, B. methylotrophicus and B. subtilis alone or in combination with Alternaria solani, Fusarium oxysporum and Phytophthora infestans. Fully ripe fruits were harvested and evaluated for carotenoid, phenol and VOCs contents. Lycopene was the most abundant carotenoid (46.4-167.62 µg/g), followed by β-carotene and lutein. Fruits from plants inoculated with Bacillus had the highest carotenoid content. In contrast, phytopathogens decreased the carotenoid contents, especially the lycopene content. The content of total phenols ranged from 0.42 to 0.90 mg GAE/g. The content of these compounds increased 1.5-fold in fruits from plants inoculated with Bacillus strains, especially those treated with B. methylotrophicus, but the greatest increase (1.9-fold) was observed in plants inoculated with phytopathogens. Both Bacillus strains and pathogens increased the antioxidant capacity, with a 2.8-fold increase compared to the control. Thirty-two VOCs were identified in the tested tomatoes. The Bacillus strains caused an increase in the concentration of VOCs, which could be associated with an increase in fruit quality.

Abstract Native starch was isolated from two corn landraces (blue and white) and a hybrid variety and then characterized for its physicochemical, thermal and rheological properties. The hybrid variety showed the highest starch yield, with its starch showing the highest fat, moisture and protein content but the lowest onset temperature of gelatinization. The hybrid corn starch also showed the highest G’ and G” values. The tested starches showed similar Tp, Tc, and ΔH values. The amylose contents ranged from 21.5 to 22.4%, with starch from blue corn showing the highest amylose content. All starches were white, with L values ranging from 93.6 to 99.5. The light absorbance of the starch gels increased with storage time. The obtained results demonstrated that the physicochemical, thermal and rheological properties of corn starch are highly dependent on the corn type.

Abtract: The objective of this study was to determine the effect of three Trichoderma species when applied alone and when are confronted with three phytopathogens on plant growth and tomato fruit quality. The substrate of the plants was inoculated with Trichoderma spp. alone and together in confrontation with Alternaria solani, Fusarium oxysporum y Phytophthora infestans. In plant, the height and weight, length and weight of roots, total chlorophyll content in leaves, and yield were determined. Fruits were characterized by color, weight, size, total soluble solids (TSS), titratable acidity, firmness and bromatological composition. Plants inoculated with Trichoderma showed significant increases in most of the variables evaluated, where T. longibrachiatum significantly promoted the growth plants (height ≥ 13%) and yield (14%), obtaining fruits with higher titratable acidity and lower TSS content. Pathogens decreased yield (23%). Diameter, firmness and protein content in fruits increased with the inoculation of Trichoderma. Color and fiber in fruits were not affected by treatments. Trichoderma strains showed potential to improve fruit quality.

Resumen: El objetivo de este estudio fue determinar el efecto de tres especies de Trichoderma cuando se aplican solas y cuando se confrontan con tres fitopatógenos, sobre el crecimiento y calidad del fruto de jitomate. El sustrato de las plantas se inoculó con Trichoderma spp. solas y en confrontación con Alternaria solani, Fusarium oxysporum y Phytophthora infestans. En planta, se determinó la altura y peso, longitud y peso de raíces, contenido total de clorofila en hojas y rendimiento. Los frutos se caracterizaron por color, peso, tamaño, sólidos solubles totales (SST), acidez titulable, firmeza y composición bromatológica. Las plantas inoculadas con Trichoderma, mostraron incrementos significativos en la mayoría de las variables de respuesta evaluadas, donde T. longibrachiatum promovió significativamente el crecimiento de la planta (altura ≥13%) y el rendimiento (14%), obteniendo frutos con mayor acidez titulable y menor contenido de SST. Los patógenos redujeron el rendimiento (23%). El diámetro, firmeza y contenido de proteína en frutos, se incrementó con la inoculación de Trichoderma. El color y fibra en frutos no resultaron afectados por los tratamientos. Las cepas de Trichoderma, mostraron potencial para mejorar la calidad del fruto.

Abstract: Mortierella species were isolated on Potato Dextrose Agar and V8-agar as well as mature pear fruits and azalea leaves as substrate baits. Four hundred and nineteen Mortierella isolates were obtained from soil samples in Chihuahua, Mexico which were classified into 21 groups, according to their morphological characters. Mortierella was isolated more frequently when pear fruits were used, obtaining 143 isolates (34.1%), followed by the V8-agar-antibiotics medium with 133 isolates (31.7%), and azalea leaves with 95 isolates (22.7%). An isolate from each of the 21 groups was identified molecularly, 12 corresponded to Mortierella alpina, one to M. gamsii, one to M. capitata, and six to Mortierella sp., and one belonged to the Mortierelliales order. In addition, the putative pathogenicity of the 21 Mortierella isolates identified was tested in G30 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.

Resumen: Se aislaron especies de Mortierella en Agar 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 frecuencia cuando se emplearon peras, obteniendo 143 aislados (34.1%), seguido del agar V8-antibióticos con 133 aislados (31.7%) y las hojas de azalea, con 95 aislados (22.7%). Se identificó molecularmente un aislado de cada uno de los 21 grupos, 12 correspondieron a Mortierella alpina, uno a M. gamsii, uno a M. capitata y seis a Mortierella sp. y uno perteneció al orden Mortierelliales. Adicionalmente se probó la patogenicidad putativa de los 21 aislados de Mortierella identificados, en porta injertos de manzana G30 bajo condiciones de invernadero y ninguno fue patogénico. Estas especies no habían sido reportadas previamente en México. El estudio demostró que existen especies de Mortierella en la rizosfera de manzanos en Chihuahua, México. Estas podrían producir ácidos grasos poliinsaturados y ejercer efectos elicitores en cultivos hortofrutícolas confiriéndoles resistencia a múltiples patógenos.

Abstract The incidence of root diseases was estimated in apple orchards from Chihuahua, Mexico. Three hundred isolates (fungi and Oomycetes) were identified in samples of root tissue and soil of trees with infectious damage symptoms and disease symptom-free trees. At the same time, putatively antagonistic agents were isolated and subsequently identified. The pathogenicity of fifteen selected isolates (eight fungi and seven Oomycetes), was tested in twelve apple rootstocks under greenhouse conditions. In addition, the in vitro antagonistic activity of Trichoderma and Bacillus species was evaluated against seven of the selected Oomycetes. The incidence of infection damage of roots in 20 tested orchards was 17% (1-40%). Fusarium was the most widely distributed fungi (67.8%). The distribution of the other organisms was variable. Four species of Trichoderma were identified, with T. gamsii being the most widely distributed (72.5%). Bacillus spp. substantially reduced the radial growth (>90%, p=0.05) of Phytophthora cactorum. Eleven rootstocks were susceptible to Pythium ultimum y Phytophthora cactorum C3. The G.935, Standard and M.25 rootstocks were the most resistant with 0% incidence. The antagonistic species of both genera inhibited the in vitro growth of P. cactorum (86.4-93.8%, p= 0.05), respect to Pythium species, and therefore, they might be used as biological control agents.

Resumen Se estimó la incidencia de enfermedades de raíz en manzanos de Chihuahua, México, y se identificaron trescientos aislados (hongos y Oomicetos) tomados del tejido de raíz y suelo de la rizosfera de árboles con síntomas de infección y libres de síntomas de enfermedad. Paralelamente, se aislaron e identificaron hongos putativamente antagonistas. Se determinó la patogenicidad de quince aislados seleccionados (ocho hongos y siete Oomicetos) sobre doce portainjertos de manzano bajo condiciones de invernadero. Adicionalmente, se evaluó la actividad antagónica in vitro de especies de Trichoderma y Bacillus contra siete de los Oomicetos seleccionados. La incidencia de daños infecciosos en raíz en 20 huertos analizados fue del 17% (1-40%). Fusarium fue el hongo más ampliamente distribuido (67.8%). La distribución del resto de los organismos fue variable. Se identificaron cuatro especies de Trichoderma, siendo T. gamsii la más ampliamente distribuida (72.5%). Bacillus spp., redujo sustancialmente el crecimiento radial (>90%, p=0.05) de Phytophthora cactorum. Once portainjertos fueron susceptibles al menos a Pythium ultimum y Phytophthora cactorum C3. Los portainjertos G.935, Standard y M.25 fueron los más resistentes con 0% de incidencia. Las especies antagonistas de ambos géneros inhibieron in vitro significativamente el crecimiento de P. cactorum (86.4-93.8%, p= 0.05), respecto a especies de Pythium, por lo que podrían ser utilizados como agentes de control biológico.