Genetic and Phenotypic Characterization of Xanthomonas Species Pathogenic in Wheat in Uruguay.

Bacterial diseases affecting wheat production in Uruguay are an issue of growing concern yet remain largely uninvestigated in the region. Surveys of 61 wheat fields carried out from 2017 to 2019 yielded a regional collection of 63 strains identified by 16S rRNA gene analysis as Xanthomonas spp. A real-time PCR protocol with species-specific primers previously reported allowed the identification of 44 strains as X. translucens, the causal agent of bacterial leaf streak (BLS) in wheat and other cereal crops. Multilocus sequence analysis of four housekeeping genes (dnaK, fyuA, gyrB, and rpoD) revealed that these strains were most closely related to X. translucens pv. undulosa, the pathovar that is most commonly associated with BLS of wheat. Multilocus sequence typing was applied to examine the genetic diversity of X. translucens strains. Strains were assigned to four different sequence types, three of which were previously reported globally. Additionally, 17 Xanthomonas strains not belonging to X. translucens were obtained from diseased wheat leaves. Phylogenetic analysis showed that these strains are closely related to X. prunicola and clustered together with previously uncharacterized Xanthomonas strains isolated from wheat in Minnesota. In planta pathogenicity assays carried out on a BLS-susceptible wheat cultivar showed that X. translucens pv. undulosa strains caused brown necrosis symptoms typical of BLS, whereas non-translucens Xanthomonas sp. strains elicited an atypical symptom of dry necrosis. These findings suggest that local wheat fields are affected by X. translucens pv. undulosa and by a new wheat pathogen within the Xanthomonas genus.

Mapping for Adult-Plant Resistance Against Septoria Tritici Blotch in a Common Wheat Line Murga.

Septoria tritici blotch (STB) is a major foliar disease globally that is notorious for quickly developing fungicide resistance, making host resistance an indispensable component in mitigating STB. The International Maize and Wheat Improvement Center (CIMMYT) wheat line Murga is well known for its high, durable, and broad-spectrum resistance against STB infection. This study aimed to investigate the resistance mechanism of Murga to facilitate its utilization in breeding. A recombinant inbred line population was derived from a cross between Murga and STB-susceptible line Huirivis#1, comprising 297 progenies. The population was evaluated for adult-plant STB resistance in Toluca, Mexico (from 2017 to 2019), and in La Estanzuela, Uruguay (from 2016 to 2018). Genotyping was performed with the DArTseq platform. Quantitative trait locus (QTL) mapping indicated a major and stable QTL on chromosome 3DL, explaining a phenotypic variation for STB of 41.2 to 62.5% in Mexico and 27.5 to 40.3% in Uruguay. This QTL was regarded as Stb16 based on the comparison of its physical position, the possible origin from synthetic wheat, and its broad-spectrum resistance. Additional QTLs with minor effects were identified on chromosomes 2B, 2D, 3A, 3B, and 5B. The QTL on 5BS was significant in four of the six environments and must be new. Murga was the resistant donor for all QTLs except for those on 2B and 3A. Being an elite breeding line, Stb16 carrier Murga could be used as a promising STB resistance donor. Rational employment of Stb16 could contribute to STB management yet avoid the rapid emergence of Stb16-virulent isolates.

Species composition, toxigenic potential and aggressiveness of Fusarium isolates causing Head Blight of barley in Uruguay.

Fusarium Head Blight (FHB) is a major constraint to barley production that substantially reduces yield and grain quality. FHB is also a major food safety concern because FHB pathogens contaminate grain with trichothecenes and other mycotoxins. DNA sequence-based analyses and in-vitro toxin assessments were used to characterize the species and trichothecene chemotype composition of FHB pathogens on barley in Uruguay. F. graminearum was the dominant species (89.7%), and three other members of the F. graminearum species complex (FGSC) were identified as FHB pathogens of barley in Uruguay for the first time. Other minor contributors to FHB species diversity included F. poae, F. avenaceum, F. pseudograminearum and an unnamed species from the F. incarnatum-equiseti species complex (FIESC). Most isolates (89.7%) had the 15-acetyldeoxynivalenol (15-ADON) trichothecene type. However, the results expanded the known area of occurrence within Uruguay for the nivalenol (NIV) toxin type, which was observed among isolates from three species of the FGSC, F. pseudograminearum, and F. poae. Isolates with the 3-acetyldeoxynivalenol (3-ADON) or NX-2 toxin types were not observed, although a previously published multilocus genotyping assay was updated to identify NX-2 strains. Analyses of population structure and comparisons with FHB isolates from wheat in Uruguay indicated that F. graminearum constitutes a single genetic population with no evidence of population differentiation related to the sampled hosts. Inter and intraspecific differences were observed in aggressiveness toward four barley genotypes with different levels of resistance to FHB, and in general nivalenol producers were the least aggressive isolates. Sensitivity to metconazole was approximately 10 times higher than was detected for tebuconazole. This is the first report regarding tebuconazole and metconazole sensitivity for Fusarium species causing FHB in barley in Uruguay, and constitutes an important starting point for monitoring temporal or spatial changes in FGSC sensitivity, which is critical to define FHB management practices.

Multi-environment multi-QTL association mapping identifies disease resistance QTL in barley germplasm from Latin America.

KEY MESSAGE: Multi-environment multi-QTL mixed models were used in a GWAS context to identify QTL for disease resistance. The use of mega-environments aided the interpretation of environment-specific and general QTL. Diseases represent a major constraint for barley (Hordeum vulgare L.) production in Latin America. Spot blotch (caused by Cochliobolus sativus), stripe rust (caused by Puccinia striiformis f.sp. hordei) and leaf rust (caused by Puccinia hordei) are three of the most important diseases that affect the crop in the region. Since fungicide application is not an economically or environmentally sound solution, the development of durably resistant varieties is a priority for breeding programs. Therefore, new resistance sources are needed. The objective of this work was to detect genomic regions associated with field level plant resistance to spot blotch, stripe rust, and leaf rust in Latin American germplasm. Disease severities measured in multi-environment trials across the Americas and 1,096 SNPs in a population of 360 genotypes were used to identify genomic regions associated with disease resistance. Optimized experimental design and spatial modeling were used in each trial to estimate genotypic means. Genome-Wide Association Mapping (GWAS) in each environment was used to detect Quantitative Trait Loci (QTL). All significant environment-specific QTL were subsequently included in a multi-environment-multi-QTL (MEMQ) model. Geographical origin and inflorescence type were the main determinants of population structure. Spot blotch severity was low to intermediate while leaf and stripe rust severity was high in all environments. Mega-environments were defined by locations for spot blotch and leaf rust. Significant marker-trait associations for spot blotch (9 QTL), leaf (6 QTL) and stripe rust (7 QTL) and both global and environment-specific QTL were detected that will be useful for future breeding efforts.

Mycobiota and mycotoxins in fermented feed, wheat grains and corn grains in Southeastern Buenos Aires Province, Argentina

El trigo (como afrechillo) y el maíz (como grano seco o alimento fermentado) son ingredientes empleados como alimento para el ganado bovino y porcino en la zona sur de la provincia de Buenos Aires (Argentina). Determinar la micobiota y las micotoxinas presentes en estos alimentos es de suma importancia para establecer técnicas de control de los mismos, optimizar la producción animal y minimizar su toxicidad. Por ende, en el sudeste de la provincia de Buenos Aires se llevó a cabo un estudio para identificar la micobiota y las principales micotoxinas presentes en dichos tipos de alimento. Las muestras fueron sembradas para realizar el recuento, el aislamiento y la identificación de los principales géneros de hongos presentes, y analizadas para detectar las micotoxinas de mayor importancia toxicológica: desoxinivalenol (DON), zearalenona (ZEA), toxina T-2 y aflatoxinas (AFLA). Penicillium (74%), Aspergillus (32%) y Scopulariopsis (21%) fueron los géneros más frecuentes en alimentos fermentados. En muestras de maíz, los géneros más relevantes fueron Penicillium (70%), Fusarium (47%) y Aspergillus (34%), mientras que Penicillium (42%), Fusarium (27%) y Alternaria (25%) fueron los más aislados en el caso del afrechillo de trigo. DON fue detectado en el 59% de las muestras de maíz, en el 45% de las muestras de trigo y en el 38% de las muestras de alimento fermentado. ZEA fue detectada en un 36% de las muestras de maíz, en un 49% de las muestras de trigo y en un 16% de las muestras de alimento fermentado. Las toxinas T-2 y aflatoxina B1 fueron detectadas en un 4% de las muestras de maíz. El 18% de las muestras de alimentos fermentados mostraron contaminación con T-2. Las muestras de alimentos fermentados y de trigo fueron negativas para AFLA(AU)

Wheat (as bran) and corn (as dry grain or fermented feed) are main ingredients of feedstuffs used in local cattle and pig farms in the South of the Buenos Aires Province (Argentina). Therefore, determining mycobiota and mycotoxins in wheat and corn is of prime importance for developing feed management techniques to optimise animal production and to minimize toxicity. Then, a mycological survey was carried out in the Southeastern part of the Buenos Aires Province, in order to identify the mycobiota and the main mycotoxins present in fermented feed, wheat grain and corn grain samples. Samples were cultured for fungal quantification, isolation and identification, and analysed for deoxynivalenol (DON), zearalenone (ZEA), T-2 toxin and aflatoxins (AFLA). Penicillium (74%), Aspergillus (32%) and Scopulariopsis (21%) were the prevalent genera in fermented feed. Penicillium (70%), Fusarium (47%) and Aspergillus (34%) were the most frequent fungi isolated from corn. Penicillium (42%), Fusarium (27%) and Alternaria (25%) were the most frequently recovered genera from wheat. DON was detected in 59% of the corn samples, in 45% of the wheat samples and in 38% of the silage samples. ZEA was detected in 36% of the corn samples, in 49% of the wheat samples and in 16% of the silage samples. T-2 toxin and aflatoxin B1 were each detected in 4% of the corn samples. Eighteen percent of the fermented feed samples showed T-2 contamination. Fermented feed and wheat samples were negative for AFLA(AU)

Mycobiota and mycotoxins in fermented feed, wheat grains and corn grains in Southeastern Buenos Aires Province, Argentina.

Wheat (as bran) and corn (as dry grain or fermented feed) are main ingredients of feedstuffs used in local cattle and pig farms in the South of the Buenos Aires Province (Argentina). Therefore, determining mycobiota and mycotoxins in wheat and corn is of prime importance for developing feed management techniques to optimise animal production and to minimize toxicity. Then, a mycological survey was carried out in the Southeastern part of the Buenos Aires Province, in order to identify the mycobiota and the main mycotoxins present in fermented feed, wheat grain and corn grain samples. Samples were cultured for fungal quantification, isolation and identification, and analysed for deoxynivalenol (DON), zearalenone (ZEA), T-2 toxin and aflatoxins (AFLA). Penicillium (74%), Aspergillus (32%) and Scopulariopsis (21%) were the prevalent genera in fermented feed. Penicillium (70%), Fusarium (47%) and Aspergillus (34%) were the most frequent fungi isolated from corn. Penicillium (42%), Fusarium (27%) and Alternaria (25%) were the most frequently recovered genera from wheat. DON was detected in 59% of the corn samples, in 45% of the wheat samples and in 38% of the silage samples. ZEA was detected in 36% of the corn samples, in 49% of the wheat samples and in 16% of the silage samples. T-2 toxin and aflatoxin B1 were each detected in 4% of the corn samples. Eighteen percent of the fermented feed samples showed T-2 contamination. Fermented feed and wheat samples were negative for AFLA.

[Comparison study of executive functions in Parkinson's disease and degenerative cerebellar disease's patients]. / Estudio comparativo de las funciones ejecutivas entre pacientes con enfermedad de Parkinson y pacientes con enfermedad degenerativa cerebelosa.

OBJECTIVE: To compare executive functions (EF) in non-demented mild to moderate Parkinson's disease (PD) (Hoehn and Yahr < or =3) and pure degenerative cerebellar disease (CD) in order to evaluate the relative contribution and differential role of basal ganglia and cerebellum in those functions. METHOD: 14 patients with PD and 14 patients with CD matched by sex, education, disease's duration and MMSE were selected. A standardized neuropsychological battery and the Wisconsin Card Sorting Test (WCST) were administered. Z scores were compared for both groups through t-test for independent samples were used. RESULTS: The cerebellar group showed significant lower performance in measures of attention and EF, with a significant increase in both perseverative and non perseverative errors during the WCST. On the other hand the PD group showed a selective increase of non perseverative errors, without reaching significant between group difference. CONCLUSION: The CD group appears to have greater deficits in EF with a pattern of prefrontal dysfunction.

Estudio comparativo de las funciones ejecutivas entre pacientes con enfermedad de Parkinson y pacientes con enfermedad degenerativa cerebelosa / Comparison study of executive functions in Parkinson's disease and degenerative cerebellar disease's patients

OBJETIVO: Comparar el rendimiento en tareas de función ejecutiva (FE) en sujetos con enfermedad de Parkinson (EP) leve a moderada (Hoehn y Yahr <3) no dementes y en sujetos con enfermedad degenerativa cerebelosa pura (EC), a fin de evaluar el eventual rol diferencial de los ganglios basales y el cerebelo en esa función. MÉTODO: Se evaluaron 14 pacientes con EP y 14 con EC apareados por sexo, educación, duración de enfermedad y MMSE, mediante tests neuropsicológicos estándar y el test de Wisconsin [WCST]). Se compararon puntajes Z promedio de cada grupo mediante prueba de "t" para muestras independientes. RESULTADOS: El grupo EC rindió significativamente menos en pruebas de atención y FE presentando errores perseverativos y no perseverativos durante el WCST. El grupo EP mostró aumento significativo de errores no perseverativos en relación al estándar esperado, sin alcanzar diferencias significativas con el grupo EC. CONCLUSION: el grupo EC mostró defectos significativamente mayores en tareas de FE exhibiendo un patrón de disfunción prefrontal.

OBJECTIVE: To compare executive functions (EF) in non-demented mild to moderate Parkinson's disease (PD) (Hoehn and Yahr <3) and pure degenerative cerebellar disease (CD) in order to evaluate the relative contribution and differential role of basal ganglia and cerebellum in those functions. METHOD: 14 patients with PD and 14 patients with CD matched by sex, education, disease's duration and MMSE were selected. A standardized neuropsychological battery and the Wisconsin Card Sorting Test (WCST) were administered. Z scores were compared for both groups through t-test for independent samples were used. RESULTS: The cerebellar group showed significant lower performance in measures of attention and EF, with a significant increase in both perseverative and non perseverative errors during the WCST. On the other hand the PD group showed a selective increase of non perseverative errors, without reaching significant between group difference. CONCLUSION: The CD group appears to have greater deficits in EF with a pattern of prefrontal dysfunction.