Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Some species of the genus Trichoderma have the ability to parasitize fungal plant pathogens. This makes them interesting in the control of diseases (anthracnose) caused by fungi in post-harvest avocado fruit. Therefore, the objective of this research was the isolation and identification of native strains of Trichoderma spp. of avocado cultures with antagonistic potential in vivo and in vitro against pathogens of this fruit. The strains were isolated from the root and soil of the avocado in the town of Tanaxuri, Michoacán. Six strains were obtained and characterized as TSONM1 (Trichoderma spp.), TRONM2 (Trichoderma spp.), TSONM3 (Trichoderma spp.), TSONM4 (Trichoderma spp.), TSONM5 (Trichoderma spp.) and TSONM6 (Trichoderma harzianum). Subsequently, the isolated strains were confronted with Neofusicoccum parvum, Colletotrichum gloeosporioides, Diaporthe sp. and Phomopsis perseae, observing in vitro inhibitions greater than 80 %. While in the in vivo evaluation, the TSONM6 strain (Trichoderma harzianum) showed greater antagonistic activity against C. gloeosporioides, Diaporthe sp. and P. persea. Additionally, the avocado fruits treated with TSONM6, presented minimum percentages (< 2%) of rotting of the pulp and peduncle. Therefore, Thichoderma harzianun could be a good alternative for postharvest biological control of avocado.

Quality protein maize (QPM) was created converting the soft opaque-2 endosperm into a vitreous phenotype, but the mechanisms involved in this modification are not completely understood. Recombinant inbred lines (RILs) derived from K0326Y QPM and W64Ao2 were used to identify quantitative trait loci (QTL) associated with starch physicochemical properties. RILs contrasting in vitreousness were also used to evaluate the expression of starch biosynthesis genes. Mapping identified 5-6 QTLs for each trait that explained 66 % of the phenotypic variation. Three QTLs on bins 4.05, 5.04, and 9.03 were found close to the starch biosynthesis genes Brittle-2 (Bt2), Amylose extender-1 (Ae1), and Waxy-1 (Wx1), respectively. The expression of Wx1 was three-fold greater in K0326Y QPM than W64Ao2 and eight-fold higher in vitreous than opaque RILs, which corresponded with the greater accumulation of granule bound starch synthase I (GBSSI) and the higher amylose content observed in the vitreous lines. The increased synthesis of amylose may result in starch granules with more amorphous regions that favor their compaction. These results suggest that endosperm modification in QPM is associated with the synthesis of starch containing more amylose during kernel development, which may facilitate the packing of the starch granules resulting in the vitreous phenotype.

Coryphantha durangensis it is an endemic cactus that lives in Mexico, in the center of the Chihuahuan desert, and is considered as Special Protection by the NOM-059-SEMARNAT-2010 One of the greatest threats to this species is climate change and habitat loss. In the present study, the climatic niche of C. durangensis was evaluated and the habitat availability of this species was modeled using the MaxEnt algorithm under current climate conditions and future. The results show a reduction in the geographical areas that present climatically suitable conditions for the presence of this species for the year 2050 and 2070, however, four sites were identified that could be proposed as conservation areas for this and other species that cohabit in these zones.

The objective of this study was to analyze the antibiotic resistance percentages of bacteria collected from health units (HU) in Hermosillo and Ciudad Obregón, Sonora, Mexico. Eight HU from Hermosillo and three HU from Ciudad Obregón, nine belong to the public sector and two to the private sector. Overall, 15,653 results of identification and drug resistance from clinical bacterial isolates were analyzed for a one-year period (2019-2020). Subsequently, a comparative study was carried out for six health units in Hermosillo, for 2014-2015 and 2019-2020 periods. Differences between populations and time periods were assessed through the Chi square test, for differences among populations and time periods. Altogether, for the 2019-2020 period the most frequently isolated microorganisms were Escherichia coli (32.9 %), Klebsiella pneumoniae (8.4 %), Pseudomonas aeruginosa (7.6 %) and Staphylococcus aureus (6.6 %). Different resistance percentages to widely used drugs such as cephalosporins, quinolones and carbapenems were detected. A significant decrease in resistance percentages was observed, in six HU in Hermosillo, for most of the antibiotics tested in 2020, compared to 2015. Significative differences were found in antibiotic resistance between clinical isolates from Hermosillo and Ciudad Obregón, two cities that are separated by only 252 km (156 miles).

The aim of the study was to assess the potential riskof exposure to V. cholerae and V. parahaemolyticus associated to raw American oyster (Crassostrea virginica) consumption collected from the Mandinga Lagoon System (MLS), in restaurants, oyster bars, and street vendors. Risk was estimated as number of cases/100,000 servings with FDA model. The risk of oyster consumption from MLS contaminated with V.cholerae noO1/noO139 chxA+ and unrefrigerated 10-h was low (99 × 10-5 cases) in summer; V. parahaemolyticus tdh+ y tdh+/trh+ estimated risk was high in spring (2,200 × 10-5 y 4,000 × 10-5 cases, respectively) and the pandemic strain orf8+ risk was medium in winter (110 × 10-5 cases). Oyster cocktailconsumption unrefrigerated for 10 h and contaminated with V. cholerae noO1/noO139 chxA+, represented a low mean risk (0.87 × 10-5 and 0.44 × 10-5 cases) for oyster cocktails from restaurants and oyster bars, respectively, a high mean risk forstreet vendor cocktails stored at ambient temperature 24 h (2,500 × 10-5 cases), and a low mean risk for V. parahaemolyticus tdh+ in restaurants (0.21 × 10-5 cases) and oyster bar (1.1 × 10-5 cases) cocktails. Risk assessment results indicated that pathogenic percentage, type of establishment, and unrefrigerated storage time were variables that most increased the probability of illness, and spring the season with the highest risk for consumers.

Xcat'ik pepper (Capsicum annuum L.), native to the Yucatan Peninsula, has unique organoleptic properties. However, the nutraceutical quality of the fruit has been scarcely explored and only a few previous studies have focused on improving the productive yield of the plant, hence the importance of generating knowledge in this field. The Capsicum species is considered an important food due to the content of bioactive compounds, which promote beneficial health effects. The use of microbial inoculants is an alternative to increase yield, improve fruit quality, and reduce the use of chemical fertilizers. In this work, the effect of a microbial consortium, as well as Bacillus subtilis and Trichoderma harzanium on the contents of ascorbic acid, total phenols, flavonoids, chlorophylls, carotenoids, antioxidant capacity and capsaicinoids in the fruit of xcat'ik pepper was evaluated. The obtained results were compared with an uninoculated control. Inoculations with T. harzanium and B. subtilis increased carotenoid content as well as antioxidant activity by ABTS+, in contrast the microbial consortium increased antioxidant activity by DPPH•. According to our results, the evaluated inoculants could replace chemical fertilizers, because they equal or improve the nutraceutical quality of the x'catik pepper fruit, with the advantage of being less harmful to the environment.

The ion concentration in the nutrient solution in a soilless system has a direct impact on the yield and quality of the crops. The objective of this research was to evaluate the effect of the electrical conductivity of the nutrient solution on the biomass, pigments and nitrogenous compounds in the lettuce crop. A randomized complete block experimental design was used with five treatments (1, 1.5, 2, 2.5 and 3 dS m-1) and nine repetitions. The total biomass (fresh and dry) and the accumulation of chlorophylls, carotenoids, proteins, amino acids, reduced glutathione and hydrophilic antioxidant capacity ABTS were determined. The results indicate that the electrical conductivity of the nutrient solution that improved biomass accumulation was 2.5 dS m-1, that of 2 dS m-1 increased proteins and amino acids, while the electrical conductivity of 3 dS m-1 improved the concentration of pigments, glutathione and increased hydrophilic antioxidant capacity ABTS, but performance decreased. Proper management of the electrical conductivity of the nutrient solution is a very important factor in improving the yield and quality of crops in soilless systems.

In this work, edible films (PCs) based on chitosan (Q), agar (A) and thyme oil (T) were prepared in four different formulations (Q, A, QA and QAT), and their mechanical properties (tension and elongation at break) and water vapor permeability were evaluated. Infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were also performed. The QA and QAT PCs stood out for their tensile strength, transparency, water vapor transmission rate and permeance, as well as the highest antioxidant activity. The effect of the application of the edible coatings (RCs) of QA and QAT on the quality of 'Hass' avocado fruit was evaluated during 13 days of storage at 25 °C. The following variables were evaluated periodically: weight loss, respiration rate, ethylene production, visual appearance, and rotting. The application of RCs to the fruit reduced their weight loss and extended their shelf life. The RCs gave the fruit a barrier to water vapor, reducing weight loss by 40 with respect to the control. In addition, the incidence of fruit rots was reduced.

Sonora, a state located in northwestern Mexico, stands out worldwide for being a producer and supplier of grains and forages, mainly wheat. The existing agroclimatic and technological conditions in the regions where wheat is grown in Sonora are favorable. There are seasons and spaces where pests become a problem and one of them is in storage. Sitophilus granarius, is a small insect which, under favorable conditions, affects up to 85% of stored wheat. Research efforts are being directed towards the development of bioproducts based on fungi or bacteria with entomopathogenic action, with potential utility as bioinsecticides. Studies related to Trichoderma harzianum and spinosyn in the control of the beetle pest of stored grains are minimal and it is in this context, the objective of this work was to evaluate the effect of Trichoderma and spinosyn in the control of Sitophilus granarius in stored wheat. For the development of the study, the grain of all the treatments was first impregnated with spinosyn; three concentrations (three treatments) of T. harzianum conidia were sprayed (T1:103, T2:106 y T3:109 conidias.mL-1), with five repetitions for each treatment. In the study they were considered controls without treatments. The exposure times of the insect to the treatments were 72, 144 and 216 h. The mortality rate was calculated. To establish the differences between treatments and controls, analysis of variance was performed. The results show that Trichoderma harzianum has a bioregulatory effect on S. granarius, which is significant when combined with spinosyn. This bioregulatory effect is emphasized when higher concentrations of 109 condia/mL are inoculated. Studies related to coinoculation and the use of spinosyn should be carried out, as well as evaluating the viability of the seed and the organoleptic properties of the grain.

Carotenoids are non-polar compounds found in fruits and vegetables. The consumption of these compounds has been associated with many beneficial effects on human health, especially on the prevention of chronic diseases that are currently considered as problems of public health. These effects have mainly been attributed to the antioxidant properties of carotenoids, although many other mechanisms are involved, including the influence of carotenoids in the expression of genes involved in the pathogenesis of these diseases. Unfortunately, the bioavailability of these compounds is very limited. The effects of several factors on carotenoid bioavailability have been studied in order to identify the best strategies to increase the absorption of these compounds and, consequently, their bioactivity. Currently, important efforts have being carried out to determine the content and bioavailability of carotenoids from underutilized foods and the mechanisms involved in their bioavailability and beneficial effects. In this review, the recent findings on carotenoid sources, bioavailability and bioactivity are discussed.