Purpose of workA simple and rapid DNA extraction protocol capable of obtaining high-quality and quantity DNA from a large number of individuals is essential for assaying population and phylogenetic studies of plant pathogens. Most DNA extraction protocols used with oomycetes are relatively lengthy and cumbersome for high throughput analysis. Commercial kits are widely used, but low quantities of DNA are usually obtained, and with large scale analysis multiple isolations are required.A protocol for DNA isolation from Phytophthora and Pythium suitable for the evaluation of a large set of molecular markers was modified from one previously developed for soybean seed. There was a one to three fold increase in the amount of DNA that was extracted using the modified protocol compared to a commercial kit. The DNA obtained using the modified protocol was suitable for the amplification of microsatellite markers as well as the ITS region. This protocol is inexpensive, easy, quick, and efficient in terms of the volume of reagents and the number of steps involved in the procedure. The method may be applicable to other oomycetes and effectively implemented in other laboratories.

<p>COVID-19 has had an impact on the regional and worldwide agricultural value chain, jeopardizing food security. It is time to reassess the approach of the agri-food sector and to consider that the food supply and plant health, as agrosystemic services, must depend on strategies with a low impact on productive and environmental assets. One strategy is the use and optimization of microbial genetic resources (MGR) related to agroecosystems as a source of balance, functionality, productivity, inhibition of the impact of pests and pathogens, and contribution to the profitability of agri-food activity. It is necessary to strengthen and develop regional agricultural systems that are dynamic, that mitigate damages to the environment and produce nutritional and nutraceutical foods that ensure human health. Agricultural sciences are undergoing changes in scientific paradigms that will benefit the agri-food sector if we are able to learn from the impacts of an extensive technological agriculture. Approaching agriculture from an agro-systemic point of view in which the crop-community is the functional biological unit of study and to preserve the MGR diversity are the greatest challenges to create sustainable and resilient strategies and technologies that contribute towards human health and help prevent risks during health crises such as the ongoing COVID-19 pandemic.</p>

Zea mays and Sorghum bicolor are important crops for animal and human nutrition worldwide. In the Central Highland Valley of Mexico, both crops are extremely important, and research is aimed toward increasing yield, disease resistance, and crop adaptation from 1,900- to 2,700-m elevation. In a 3-year field breeding experiment (2004 to 2006), leaf blight and vascular wilt symptoms were frequently observed in contiguous plots of maize and sorghum crops in Montecillo, Mexico and maize plots in Tecamac, Mexico. To identify and characterize the causal agent of these symptoms, isolations were conducted on leaves from areas where healthy and diseased tissues converged. Leaf sections of 1 cm2 from both crops were disinfested, placed on casamino acid-peptone-glucose (CPG) medium, and incubated at 28°C. After 48 h, only yellow colonies were observed and 12 isolates were selected for further characterization. Physiological and biochemical tests indicated that the isolates were nonfluorescent on King's B medium, and API 50 CHE (bioMérieux, Marcy l'Etoile, France) revealed that they were negative for gelatin hydrolysis, indole production, acid production from raffinose and positive for utilization of glycerol, D-glucose, mannitol, arbutine, esculine, salicine, cellobiose, maltose, melibiose, D-fucose, and D-arabitol; all characteristics of Pantoea agglomerans. Further identification of these isolates was accomplished by DNA analysis. For DNA analysis, 1.4-kbp fragments of the 16S rRNA gene were amplified with primer set 8F/1492R (3) and sequenced with U514F/800R universal primers (2). Five sequences were obtained and deposited in GenBank (Accession Nos. EF050806 to EF050810). A phylogenetic tree was constructed using the UPGMA method (mega version 3.1). Results of the phylogenetic analysis grouped the species P. ananatis, P. stewartti, and P. agglomerans into three clusters. The five unknown sequences were grouped into the P. agglomerans cluster. There was a 98 to 99% similarity of the five 16S rRNA gene sequences with P. agglomerans strain type ATCC 27155. Pathogenicity of the 12 isolates was confirmed by injecting 108 CFU mL–1 of inoculum into stems of 3-week-old maize cv. Triunfo and sorghum cold tolerant hybrid (A1×B5)×R1 seedlings in the greenhouse at 28°C and 80% relative humidity. Also, seedlings were inoculated with water, nonpathogenic isolates of P. agglomerans from maize (GM13, and HLA1), and not inoculated as negative controls. Three replications were included for each isolate and control. All test strains developed water-soaked lesions on juvenile leaves at 8 days postinoculation and were followed by chlorotic to straw-colored leaf streaks and then leaf blight symptoms at 3 weeks postinoculation. All negative control seedlings did not develop symptoms. In addition, the 12 isolates were infiltrated at 107 CFU mL–1 into tobacco leaves that displayed a hypersensitive response at 4 days, indicating the presence of the type III secretion system (1). Isolates were reisolated, and the 16S rRNA gene fragments were 100% similar to their original isolate sequences. P. agglomerans has been reported to affect other crops, including chinese taro in Brazil (2007), onion in the United States (2006) and South Africa (1981), and pearl millet in Zimbabwe (1997); however, to our knowledge, this is the first report of P. agglomerans associated with leaf blight and vascular wilt symptoms in maize and sorghum in the Central Highland Valley of Mexico. References: (1) J. Alfano and A. Collmer. Annu. Rev. Phytopathol 42:385, 2004. (2) Y. Anzai et al. Int. J. Syst. Evol. Microbiol. 50:1563, 2000. (3) M. Sasoh et al. Appl. Environ. Microbiol. 72:1825, 2006.

The bacterial community of the artisanal Adobera cheese from Los Altos de Jalisco was described through high-throughput sequencing of 16S rRNA gene libraries. Samples were collected in two different seasons (dry and rainy) during four key steps of the manufacturing process (raw milk, fresh curd, matured curd, and cheese). Bacterial diversity was higher in early steps in comparison with the final elaboration stages. Firmicutes and Proteobacteria were the most abundant phyla, strongly represented by the Streptococcaceae, Enterobacteriaceae and Lactobacillaceae families, and core bacteria genera such as Streptococcus spp., Lactococcus spp., and Lactobacillus spp. Undesirable bacteria, including Pseudomonas spp. and Acinetobacter spp., were also detected in raw milk but almost undetectable at the end of the cheese manufacturing process, and seemed to be displaced by lactic-acid bacteria-related genera. Seasonal effects were observed on the community structure but did not define the core microbiota composition. Predictive metabolism was related to membrane transport, and amino-acid, lipid, and carbohydrate metabolism pathways. Our results contribute to deduce the role of bacteria involved in Adobera cheese manufacturing in terms of the metabolism involved, cheese microbial safety, and how undesirable bacterial populations could be regulated by process standardization as a potential tool to improve safety.

<p>Actualmente, los estudios sobre agentes de control biológico de origen microbiano (ACB-M) generalmente están enfocados en la caracterización taxonómica mediante el uso de marcadores moleculares convencionales y en evaluar la capacidad antagónica/mecanismos de acción <em>in vitro</em>, en invernadero y eventualmente bajo condiciones de campo. Los ACB-M se centran principalmente en cepas de <em>Trichoderma</em>, <em>Paecilomyces, Beauveria</em>, <em>Pseudomonas</em> y <em>Bacillus</em>. Aunque la investigación en México en este campo ha sido muy activa en los últimos años, el desarrollo e innovación de una mayor diversidad de bioplaguicidas registrados y comercializados puede ser potenciada. En este contexto, el uso de técnicas vanguardistas en la era de las ciencias ómicas (genómica, transcriptómica, y metabolómica) enfocadas a la correcta afiliación taxonómica de los ACB-M y en el estudio de mecanismos de acción y comportamiento agroecológico es determinante para la bioprospección y uso extensivo de estos ACB-M de manera eficaz, biosegura y costo-efectiva. En el marco de la celebración internacional de la sanidad vegetal, la presente revisión analiza críticamente el estado del conocimiento y de aquellos aspectos que limitan la bioprospección y el uso extensivo de ACB-M con énfasis en México, desde la aplicación de las ciencias ómicas para la identificación, selección y estudio de los mecanismos de acción de dichos agentes hasta la difusión y socialización del conocimiento científico generado. Se pretende promover la reflexión sobre este campo del conocimiento e incentivar la nueva generación ACB-M con una visión holística y sistémica en beneficio de una agricultura sustentable y resiliente.</p>