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The use of resistant wheat cultivars is a fundamental strategy to minimize the damages caused by blast, a disease caused by the fungus Pyricularia oryzae Triticum (PoT). The objetive of this stydy was to (a) evaluate the reaction to blast of Brazilian wheat cultivars and (b) determine whether there is correlation between severity of symptoms on wheat spikes and "sporulation rate of PoT conidia per gram of wheat spike rachis" (Rscon). Plants of 16 wheat cultivars were grown in greenhouse until flowering (Zadoks stage 65), when their spikes were inoculated with a suspension formed by mixing the conidia of three PoT isolates. The evaluated variables were blast severity on spikes at 5, 7 and 11 days after inoculation (dai) and Rscon. Rachis were evaluated individually to determine the Rscon. Correlation analyzes were carried out between blast severity means on spikes of cultivars at 5, 7 and 11 dai and Rscon. The cultivars TBIO Mestre, TBIO Aton, ORS 1401, ORS 1403, ORS Destak, ORS Feroz, and CD 116 stood out for being classified in the statistical groups with the highest resistance to blast for the four variables considered in the study. The correlation between blast severity on spikes at 5, 7 and 11 dai and Rscon is at most moderate. [ABSTRACT FROM AUTHOR]

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La pudrición de raíz y tallo, más conocida como “damping-off” es un problema recurrente en muchos cultivos y asociada a patógenos como Pythium sp. y Phytophthora sp., Phytophthora sojae; y una importante limitación para la producción mundial de soja. Previamente, se identificó a la accesión PI 408029 como una potencial fuente de nuevos genes de resistencia (Rps) a P. sojae. El objetivo de este estudio fue la identificación y el mapeo de los loci Rps asociados a la resistencia a las patotipos de P. sojae OH1 (vir 7), OH4 (vir 1a, 1c, 7), OH25 (vir 1a, 1b, 1c, 1k, 7), OH7 (1a, 2, 3a, 3b, 3c, 4, 5, 6, 7) y 1.S.1.1 (1a, 1b, 1k, 2, 3a, 3c, 4, 5, 6, 7, 8) en una población de líneas recombinantes (RIL) resultante del cruce entre Williams (susceptible a PRSR) y PI 408029 (resistente a PRSR). Un cruce específico entre Williams y PI408029 fue realizado en el Centro de Investigaciones de Wooster de la Universidad Estatal de Ohio y las líneas segregantes fueron avanzadas siguiendo el método de descendencia de semilla única hasta la F7. Un total de 93 RILs fueron genotipadas usando en Infinium Soy-6K Beadchip array y fenotipadas usando patotitpos de P. sojae OH4, OH7, OH25, y 1S.1.1. El mapeo se realizó usando la función de Kosambi para determinar recombinaciones significativas. Las asociaciones fenotipo-genotipo (GWAS) fueron analizadas con la función de intervalo de mapeo compuesto CIM. La resistencia fue conferida por uno o dos genes Rps dominantes, dependiendo del aislado de P. sojae. Se detectó un nuevo locus Rps en el cromosoma 13 relacionado con OH4 y OH25. El locus restante para OH7 y 1.S.1.1 se encontraba en un locus conocido en el cromosoma 3. Un análisis comparativo de secuencias entre PI 408029 y Williams82 (Wm82.a2.v1), seguido de una PCR cuantitativa en tiempo real de 14 genes, condujo a la identificación de 2 genes de proteínas resistentes a enfermedades con repeticiones ricas en leucina (Glyma.03g048100 y Glyma.03g037000)[1], que se expresaron de manera aumentada tras la inoculación en un ensayo de tiempo con 1.S.1.1, y un gen de proteína quinasa similar a receptores (Glyma.13g050500) y un TIR-NB-LRR[2] (Glyma.13g078200) con OH4 y OH25. Los genes y marcadores de este estudio podrían utilizarse en el mejoramiento de cultivares resistentes a Phytophthora y en futuros estudios sobre la respuesta cualitativa de defensa funcional frente a P. sojae. [1] Glyma genes (Glicine max) [2] Genes que contienen terminales Nucleotide Binding Site - Leucine Rich Repeat

The yam Dioscorea spp., Is a crop of economic importance in the Colombian Caribbean, it is part of the food and sustenance diet for the producers. Anthracnose Colletotrichum gloeosporioides is one of the most limiting diseases in the production of yam, with losses between 50 and 100 % being reported in Colombia. The resistance to anthracnose was evaluated in 84 accessions of D. alata and 28 of D. rotundata, belonging to the collection of yam from the University of Córdoba, at 120, 150 and 180 days after sowing DDS, using a severity scale of 0-6. The accessions were classified according to their resistance, using the method of the sum of ranges of the area under the ABCPE progress curve and the method of severity at 120, 150 and 180 DDS. The severity at 180 DDS had a strong linear relationship r = 0,99 with the integral variable area under the ABCPE disease progression curve and the TPE disease progression rate. The classification of resistance by the rank sum method was the most efficient, identifying in D. alata 18 resistant R accessions, 24 moderately resistant MR, 26 moderately susceptible MS and 16 susceptible S. In the species D. rotundata were identified 5 accessions R, 8 MR, 8 MS, 6 S. The yam collection at the University of Córdoba has accessions with resistance to anthracnose, and it is important to start improvement work with these accessions to identify their agronomic characteristics. [ABSTRACT FROM AUTHOR]

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Objetivo. Caracterizar dos polimorfismos genéticos tipo SNP en los genes GLI1 (rs411868094) y IL20RA (rs419463995) candidatos a la resistencia contra parásitos gastrointestinales en dos biotipos de ovinos de pelo colombiano. Materiales y métodos. Del banco de ADN del laboratorio de Genética Animal de la Universidad de Sucre, se analizaron 167 muestras de ovino de pelo colombiano (OPC), pertenecientes a los biotipos Etíope (n=94) y Sudán (n=73), mediante PCR y secuenciamiento bidireccional dos SNPs en los genes GLI1 (T>G) y IL20RA (G>A). Se calcularon las frecuencias alélicas y genotípicas, la heterocigocidad observada (Ho) y esperada (He), el índice F y las desviaciones del equilibrio de Hardy-Weinberg (EHW) con el programa GENALEX versión 6.5. Resultados. Para el gen GLI1 para todo el OPC las frecuencias genotípicas promedio fueron 0.155±0.07, 0.370±0.07 y 0.475±0.07 para GG, GT y TT, respectivamente. En el biotipo Etíope, se encontraron las frecuencias más altas del genotipo GG. Para el gen IL20RA en todo el OPC, los genotipos AA y AG tuvieron similar frecuencia (0.465±0.03) y el genotipo GG mostró la frecuencia más baja (0.110±0.01). Conclusiones. Las variantes genéticas analizadas fueron polimórficas. Según los reportes de literatura, los alelos de interés por su mejor desempeño contra los parásitos gastrointestinales, tuvieron baja frecuencia en el gen GLI1, pero alta frecuencia en el IL20RA.

Black pod rot (BPR), caused by several species of the genus Phytophthora, is one of the most limiting diseases for the production of cocoa as it appears in all of the producing regions of the world and generates significant losses. The aim of this study was to establish the response to this infection in six cacao clones (EET8, IMC67, TSH565, PA46, ICS95, and CCN51), through an inoculation test on detached fruits using five P. palmivora isolates from five producing regions. The incidence and severity of the disease in the detached pods were evaluated at six and ten days after inoculation (DAI). Clone CCN51 was classified as susceptible, and clones IMC67 and PA46 as moderately susceptible at six DAI. All the clones evaluated were categorized as susceptible at ten DAI. The HURV19 isolates of P. palmivora showed the highest aggressiveness compared to ANYA228, which was found to be the least aggressive. [ABSTRACT FROM AUTHOR]

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La podredumbre carbonosa de la soja [Glycine max (L.) Merr.], ocasionada por el hongo polífago Macrophomina phaseolina (Tassi) Goid., es una enfermedad que ocasiona pérdidas económicamente importantes en el mundo. En el noroeste de Argentina esta patología es limitante para la producción de soja cuando se presentan condiciones de altas temperaturas y estrés hídrico. Debido a la importancia económica y a la falta de genotipos comerciales de soja resistentes a esta enfermedad, se planteó como objetivo evaluar el comportamiento de las líneas avanzadas de soja del programa de mejoramiento genético de la Estación Experimental Agroindustial Obispo Colombres (EEAOC) frente a la podredumbre carbonosa, en ensayos a campo inoculados con el hongo. Se evaluaron los parámetros de severidad e índice de unidades formadoras de colonias de M. phaseolina (IUFC) en estadio fenológico R7 del cultivo. Se evaluaron 12 líneas de soja en la campaña 2016/2017 y 24 líneas en el ciclo agrícola 2017/2018. Las líneas que presentaron los mejores comportamientos frente a M. phaseolina en los ciclos agrícolas evaluados fueron: D38M3-13/182, D51N59-14/247 y Munasqa RR, las cuales se comportaron como moderadamente resistentes cuando se evaluó el parámetro severidad, y como resistentes según el parámetro IUFC. Estas líneas podrían ser utilizadas en los programas de mejoramiento genético como progenitores para incorporar la resistencia frente a esta enfermedad, y mejorar así el manejo de la podredumbre carbonosa de la soja en el noroeste de Argentina de forma eficaz y amigable con el ambiente.

Objetivo Evaluar la segregación fenotípica contra nematodos gastrointestinales a partir del conteo fecal de huevos en cabras lecheras del municipio Martí, en la provincia de Matanzas, Cuba. Materiales y Métodos El estudio se realizó en un rebaño caprino lechero en el municipio Martí, de la provincia de Matanzas, Cuba, de mayo a diciembre de 2017. Se tomaron muestras fecales individuales para la determinación del conteo fecal de huevos y se registró mensualmente la condición corporal de 52 reproductoras. Se establecieron cuartiles (Q), según el conteo fecal de huevos por mes. Se clasificaron como altos eliminadores, los animales que en 60 % de los muestreos estuvieron en el Q4; fueron bajos eliminadores los que en 60 % estuvieron en el Q1 y 40 % en los cuartiles intermedios, pero con conteo fecal de huevos que nunca fue superior a 1,500 huevos por gramo; la categoría de eliminadores intermedios correspondió a los animales que se hallaron en los intercuartiles Q2 y Q3. Resultados Se segregaron las cabras en tres grupos: cuatro clasificadas como bajas eliminadoras, 42 como intermedias, y seis como altas, con promedios de huevos en los conteos fecales de 485,9; 1 498,2 y 1 895,8 para cada grupo, respectivamente. La moda de la condición corporal en cada grupo no mostró diferencias (3). Conclusiones La segregación de las cabras mediante el conteo fecal de huevo permitió la identificación de la variabilidad fenotípica existente entre los animales en la susceptibilidad al parasitismo gastrointestinal. De este modo, se crean las bases para la evaluación, en un futuro, de un programa de mejoramiento genético mediante selección, para animales resistentes al parasitismo gastrointestinal.

Among the maize leaf diseases, white leaf spot, northern leaf blight, gray leaf spot, and southern rust are recognized not only by the potential for grain yield reduction but also by the widespread occurrence in the producing regions of Brazil and the world. The aim of this study was to characterize common maize lines for resistance to white leaf spot, northern leaf blight, gray leaf spot, and southern rust and suggest crosses based on the genetic diversity detected in SNP markers. The experiment was conducted in a randomized block design with three replications in order to characterize 72 maize lines. Genotypic values were predicted using the REML/BLUP procedure. These 72 lines were genotyped with SNP markers using the 650K platform (Affymetrix®) for the assessment of the genetic diversity. Genetic diversity was quantified using the Tocher and UPGMA methods. The existence of genetic variability for disease resistance was detected among maize lines, which made possible to classify them into three large groups (I, II, and III). The maize lines CD 49 and CD50 showed a good performance and can be considered sources of resistance to diseases. Therefore, their use as gene donors in maize breeding programs is recommended. Considering the information of genetic distance together with high heritability for leaf diseases, backcrossing of parent genotypes with different resistance levels, such as those of the lines CD49 x CD69 and CD50 x CD16, may result in new gene combinations, as they are divergent and meet good performances.

Danos causados por formigas cortadeiras em vimeiros têm provocado perdas de produção e qualidade de varas para o artesanato, devido às brotações laterais que provocam. Este trabalho teve o objetivo de estimar a época crítica para a perda de peso e a mortalidade de estacas da espécie, Salix viminalis, devido aos danos causados pelas formigas cortadeiras, principalmente Acromyrmex spp., e a preferência de forrageamento sobre clones de Salix spp. Experimentos foram conduzidos no campo, no período de 2003 a 2005, em vimeiros implantados na comunidade de Lambedor, Lages, SC. A espécie de vime S. viminalis foi suscetível ao ataque das formigas cortadeiras Acromyrmex spp., durante todo o seu ciclo de cultivo, com possibilidade de 20% de mortalidade de estacas/mudas até os 3 meses de idade no período de implantação do vimeiro. A maior preferência de forrageamento das formigas Acromyrmex spp. foi pelos clones EEL_01 e EEL_52 (Salix viminalis), EEL_23 (Salix x rubens) e EEL_62 (Salix triandra), usados no artesanato. Os menos preferidos foram EEL_49 (Salix matsudana-tortuosa) e EEL_11 (Salix caprea), ambos ornamentais, e EEL_10 (S. nigra) usado como madeira.

The evolution in virulence of Puccinia coronata f. sp. avenae has challenged the genetic resistance to crown rust in oat genotypes. New resistance sources are constantly required for yield stabilization and costs reduction. This study aimed to characterize the crown rust resistance of oat genotypes and the disease's productive and economic impact. Experiments were conducted in two environments, with and without chemical control. Resistance was measured by disease progress, apparent rate of infection, final severity and pustule size. Damages were based on reduction of yield, 1000 grain mass and hectoliter mass. UFRGS16Q6030-2 was immune. In both environments, UFRGS166091-2 and URS Brava exhibited the greatest level of resistance and the smallest grain yield reduction, while URS 22 was highly susceptible, reducing more than 70% of its grain yield. These results surpass the negative impacts of the disease previously reported in oats, particularly related to grain yield. The data presented in this paper highlighted the importance of genetic resistance, particularly partial resistance, for maintaining oat genetic yield potential, reducing environmental contamination with less fungicides, and increasing economic gains with oat cultivation. [ABSTRACT FROM AUTHOR]

The basidiomycet Sporisorium reilianum f. sp. zeae infects the maize plant causing important losses in regions with adequate conditions for disease development. In this work, the response to selection of six and five cycles of selection in a white and a yellow endosperm maize populations improved through S1 recurrent selection for desirable agronomic characters, grain yield and resistance to head smut were evaluated. In a separate trial, same cycles were planted to measure progress in disease resistance and to evaluate a new method of inoculation were artificially inoculated. A randomized complete block design with three replications was used for the yield trials and two replications in the inoculated trial. Cycles evaluated in the two populations showed an increase in disease resistance of 0.94 y 1.2% cycle-1, and a genetic gain in grain yield of 272.9 y 620 kg ha-1 cycle-1 for the white and yellow endosperm populations, respectively. Results showed that recurrent S1 selection was efficient in improvement of grain yield and resistance to head smut in both populations. [ABSTRACT FROM AUTHOR]

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Yam (Dioscorea spp.) is an edible tuber of economic importance in tropical regions, and a staple for more than 155 million people. Yam crop yields can be affected by devastating diseases such as anthracnose (Colletotrichum spp.), which can cause up to 80% loss in endemic areas, if control measures are not implemented. The following article is aimed to review the research conducted on anthracnose in yam, its biology and epidemiology, symptomatology, etiology and different management strategies. Disease symptoms, biology and epidemiology of the causal agent, Colletotrichum gloeosporioides, are described. Finally, the different management strategies such as genetic, cultural, biological and chemical control are presented. Integration of control methods should be used for disease management, starting with selection of fields with low amounts of primary inoculum, planting resistant or tolerant genotypes and using healthy asexual vegetative material protected with fungicides. [ABSTRACT FROM AUTHOR]

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Phomopsis longicolla (Plo) and P. phaseoli var. sojae (Pps) are causal agents of stem blight (SB) and seed decays (SD) in soybean (Glycine max). The objective was to study genetic and pathogenic variability of Phomopsis in interactions with cultivars of varied resistance or susceptibility, and to study the association between molecular and pathogenic profiles in the analyzed interactions. The hypothesis was that the existence of genetic variability in both fungus and plant materials increases the biodiversity in specific reactions during the development of SB. For contrasting this hypothesis, a new approach of the widely known statistical methods GGE Biplot was proposed for measuring the correlation among pathogenic attributes (phenotypic expression of the plant pathology) and molecular markers. Six isolates of Plo and one of Pps were inoculated to six soybean cultivars. Genetic variability in the fungi was evaluated at the molecular level by RAPD and ITS markers and at the phenotypic level by their pathogenic performance through the severity (S%) of the pathology caused in soybean cultivars. Molecular characterization separated the Plo isolates from the Pps isolate. Specific interaction between each isolate'cultivar combination evidenced differential pathogenic performances in respect to resistance/susceptibility. The study identified associations between the molecular variability of pathogens and the differential behavior observed in the set of soybean cultivars that interacted with Phomopsis isolates that cause TTV in G. max. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the phenotypic segregation against gastrointestinal nematodes from the fecal egg count in dairy goats of the Martí municipality, in Matanzas province, Cuba. Materials and Methods: The study was conducted in a dairy goat flock in the Marti municipality, of Matanzas province, Cuba, from May to December, 2017. Individual fecal samples were taken for determining the fecal egg count and the body condition of 52 does was monthly recorded. Quartiles (Q) were established, according to the fecal egg count per month. The animals that in 60% of the samplings were in Q4, were classified as high eliminators; the animals that in 60% were in Q1 and 40% in the intermediate quartiles were low eliminators, but with fecal egg count which was never higher than 1,500 eggs per gram; the category of intermediate eliminators corresponded to the animals that were found in the interquartiles Q2 and Q3. Results: The goats were segregated in three groups: four classified as low eliminators, 42 as intermediate, and six as high, with egg averages in the fecal counts of 485,9; 1 498,2 and 1 895,8 for each group, respectively. The mode of the body condition in each group did not show differences (3). Conclusions: The segregation of goats through fecal egg count allowed the identification of the existing phenotypic variability among the animals in the susceptibility to gastrointestinal parasitism. Thus, the bases are created for the evaluation, in the future, of a breeding program through selection, for gastrointestinal parasitism-resistant animals. [ABSTRACT FROM AUTHOR]

In maize production, farmers face the alternative of planting commercial hybrid maize seed, or an open pollinated variety including an improved variety or a native local variety. Hybrid maize seed is costly, new seed has to be planted each season and seed of the desired hybrid is difficult to find, while seed of an improved open pollinated variety can be planted for several years, at par in grain yield with a hybrid, it is of low cost, and can be shared between farmers. The advantage of an open pollinated synthetic variety over a normal improved open pollinated variety is a higher grain yield, more uniformity in flowering time and phenotype. This work presents activities resulting in obtaining the open pollinated synthetic variety with white endosperm CP-Vero 1 following an S1 recurrent selection program for good agronomic characters and resistance to head smut. [ABSTRACT FROM AUTHOR]

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Soybean is among the crops most affected by the presence of nematodes, resulting in large losses in productivity each year. The aim of this study was to verify and confirm the relationships of tolerance, resistance, and susceptibility of six soybean cultivars to the parasitism of five nematode populations belonging to three species of Meloidogyne (M. javanica, M. arenaria, and M. morocciensis). Seedlings of each soybean genotype (BMX Potência RR, BMX Turbo RR, TEC 6029 IPRO, Fundacep 58 RR, FPS Urano RR, and BMX Ponta IPRO) were grown in a greenhouse and inoculated with 2,000 eggs + secondstage juveniles of each population of Meloidogyne population separately, using six replicates per treatment. After 75 days, the gall index (GI) and the reproduction factor (RF) were determined. Among the cultivars tested, most of them were susceptible to nematode galling, regardless of the origin of the nematode population. Only the cultivar BMX Turbo RR demonstrated a resistance reaction to M. arenaria and M. morocciensis. [ABSTRACT FROM AUTHOR]

Common bean (Phaseolus vulgaris L.) is the most important edible legume in the world and is an important source of income for farmers and food for millions of families. Angular Leaf Spot (ALS), caused by the fungus Pseudocercospora griseola (Sacc.) Ferraris, is one of the most important diseases in the production of common bean with the potential to cause significant seed yield losses. An effective and environmentally friendly alternative to control this disease is the use of improved varieties that combine resistance genes of Andean and Mesoamerican origin. In this study, the response of 181 bean genotypes (coming from different breeding programs of several countries including the USA, Puerto Rico, Honduras, Ecuador, Colombia, Tanzania, Malawi, and Angola) to two angular spot isolates (races 61:11 and 63:51, prevalent in Isabela and Juana Díaz, Puerto Rico) were evaluated. Many of these genotypes contained resistant genes to different biotic and to abiotic stress. A total of 16 lines were identified to have resistance to both races. The resistant lines include the Andean breeding lines CAL 143, 277 and the Mesoamerican cultivar 'Ouro Negro' that possess the resistance genes Phg-5, Phg-1, Phg-3, respectively. This information can help common bean breeding programs to pyramid genes from the Andean and Mesoamerican gene pools to generate varieties with long-lasting resistance to this disease. [ABSTRACT FROM AUTHOR]

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Resumo: O objetivo deste trabalho foi elaborar e validar um protocolo de detecção simultânea, via reação em cadeia da polimerase multiplex (PCR multiplex), de regiões genômicas do tomateiro (Solanum lycopersicum) associadas a fatores de resistência às três raças fisiológicas de Fusarium oxysporum f. sp. lycopersici (FOL). Os pares de iniciadores empregados foram SSR-67 (específico para o gene I-1), TFusrr (específico para o gene I-2) e SSRD (específico para o gene I-3). Os resultados de genotipagem com marcadores moleculares foram comparados aos resultados de fenotipagem de uma coleção de germoplasma de tomateiro, em bioensaios de inoculação de isolados das três raças de FOL em plântulas, pelo método de imersão das raízes. A resistência ou a suscetibilidade foi confirmada por PCR, por meio de visualização dos âmplicons específicos para as regiões-alvo ligadas aos fatores de resistência às distintas raças de FOL. O protocolo elaborado para o uso conjunto dos marcadores moleculares, em PCR multiplex, permite a seleção de acessos de tomateiro resistentes às raças 1, 2, e 3 de F. oxysporum f. sp. lycopersici de maneira similar à realizada com a utilização de cada um separadamente. O PCR multiplex representa uma ferramenta viável para monitorar a incorporação desses fatores de resistência em linhagens de tomateiro.

Abstract: This study was designed to assess the influence of genetic resistance against brachiaria poisoning in sheep. Two groups of sheep, one identified as susceptible (formed by two ewes and one ram) and the other as resistant against brachiaria poisoning (formed by three ewes and one ram) were selected. Sheep considered susceptible were those that presented clinical signs of brachiaria poisoning at any time of their life; resistant sheep were those that even raised on Brachiaria spp. pastures, did not developed any sign of the poisoning during their life. The offspring of the two flocks (15 lambs from the sensitive flock and 9 lambs from the resistant flock) were placed into brachiaria pasture (initially Brachiaria decumbens and B. brizantha,and only B. decumbens after weaning) and followed up during two years (2013-2014). The determination of protodioscin levels in B. decumbens pasture was performed only in 2014 and revealed significant amounts of the toxic principle. Eleven lambs of the susceptible group were affected to some degree of brachiaria poisoning and six died; no lamb of the resistant group was affected. Clinical signs consisted of varying degrees of subcutaneous edema of the face and, erythema and loss of hair of the ears, crusts on the skin of ears, around the eyes and on planum nasale, scar deformation of the ears, and bilateral ocular discharge; affected lambs also sought for shadowy shelters and they were poor doers. Several sheep recovered from the condition and then relapsed. Necropsy findings in six lambs included pale mucous membranes, emaciation, dermatitis, scar deformation of the ears, large yellow livers with marked lobular pattern, and moderate infestation by Haemonchus contortus. Histologically the liver lesions were similar in all necropsied lambs but with varying degrees of severity; they were consistent with brachiaria poisoning and included architectural disruption of hepatocellular trabecula, clusters of foamy macrophages occasionally forming multinucleated giant cells, swollen and vacuolated hepatocytes, crystals or negative images of crystals in the biliary system, bilestasis, bile duct proliferation and lymphoplasmacytic infiltrate in portal triads. The skin lesions were those of photodermatitis and included epidermal necrosis, hyperkeratosis and dermal neutrophilic infiltrate. The results of this study allow to conclude that there is a genetic related resistance to brachiaria poisoning in sheep since the progeny of resistant sheep did not manifest the poisoning. The use of resistant flocks in brachiaria pastures is suggested as a valuable option for the prevention of brachiaria poisoning in sheep.

La antracnosis causada por Colletotrichum lindemuthianum, es una de las enfermedades de mayor importancia económica del cultivo de fréjol (Phaseolus vulgaris L.) en Ecuador. La mejor alternativa de control es el uso de variedades resistentes. C. lindemuthianum presenta gran variabilidad patogénica lo que dificulta el desarrollo de variedades con resistencia duradera, por tanto, el conocimiento de la presencia y distribución de las razas fisiológicas del patógeno y la identificación de genes de resistencia son claves para desarrollar variedades con resistencia amplia y duradera. El objetivo de esta investigación fue determinar la variabilidad patogénica de C. lindemuthianum y la resistencia de genotipos de fréjol de Ecuador. La investigación se desarrolló en los años 2013 y 2014. Se caracterizaron diecisiete aislamientos de C. lindemuthianum procedentes de la región centro norte de Ecuador, por medio de la inoculación de un grupo de doce variedades diferenciales estándar. Entre las muestras analizadas se identificaron trece razas, cinco de las cuales no habían sido reportadas previamente en el país. La variedad diferencial G2333 (Co-42, Co-52 y Co-7) presentó resistencia a todas las razas caracterizadas en Ecuador. Adicionalmente, veintiún variedades mejoradas y líneas élite de fréjol fueron evaluadas con dieciséis de los diecisiete aislamientos caracterizados, se identificaron tres genotipos (TB2, TB3 e INIAP 485 Urcuquí), con resistencia a los aislamientos en mención. Las fuentes de resistencia identificadas en este estudio permitirán planificar el desarrollo de variedades de fréjol con resistencia amplia y duradera a C. lindemuthianum.

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The objective of this work was to produce a polyclonal antiserum against the coat protein (CP) of Papaya lethal yellowing virus (PLYV) and to determine its specificity and sensibility in the diagnosis of the virus, as well as to evaluate the genetic resistance to PLYV in papaya (Carica papaya) accessions and to investigate the capacity of the two-spotted spider mite Tetranychus urticae to acquire and transmit PLYV to the plants. Sixty-five papaya accessions were evaluated. For each accession, ten plants were mechanically inoculated using PLYV-infected plant extracts, and three plants were mock inoculated with phosphate buffer alone and used as negative controls. Ninety days after inoculation, newly-emerging systemic leaves were collected from the inoculated plants, and viral infection was diagnosed by indirect Elisa, using polyclonal antiserum sensible to the in vitro-expressed PLYV CP. Viral transmission by T. urticae was evaluated in greenhouse. The experiments were repeated twice. Polyclonal antiserum recognized the recombinant PLYV CP specifically and discriminated PLYV infection from infections caused by other plant viruses. Out of the 65 papaya accessions evaluated, 15 were considered resistant, 18 moderately resistant, and 32 susceptible. The two-spotted spider mite T. urticae was capable of acquiring PLYV, but not of transmitting it to papaya.

Copyright of Brazilian Journal of Applied Technology for Agricultural Science / Revista Brasileira de Tecnologia Aplicada nas Ciências Agrárias is the property of Brazilian Journal of Applied Technology for Agricultural Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cientifica is the property of Fundacao de Apoio a Pesquisa e Extensao and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Ceres is the property of Revista Ceres and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Anthracnose caused by Colletotrichum lindemuthianum is one of the most economically important diseases of bean (Phaseolus vulgaris L.) cultivation in Ecuador. The best control alternative is the use of resistant varieties. C. lindemuthianum presents great pathogenic variability, which hinders the development of varieties with a lasting resistance, therefore, the knowledge of the presence and distribution of the physiological races of the pathogen and the identification of resistance genes are key to developing varieties with broad and lasting resistance. The objective of this research was to determine the pathogenic variability of C. lindemuthianum and to evaluate the resistance of Ecuadorian bean germplasm. The research was carried out between 2013 and 2014. Seventeen isolates of C. lindemuthianum from northern central Ecuador were characterized by the inoculation of a group of twelve standard differential bean varieties. Among the analyzed samples, thirteen races were identified; five of those races had not been previously reported in the country. The differential G2333 (Co-4², Co-5² and Co-7) presented resistance to every characterized races in Ecuador. In addition, twenty - one improved varieties and elite bean lines were evaluated with sixteen of the seventeen isolates, three genotypes were identified (TB2, TB3 and INIAP 485 Urcuquí) with resistance to the mentioned isolates, which can be used as sources of resistance to Anthracnose. The identified sources of resistance in this study will allow to plan the development of bean varieties with broad and durable resistance to C. lindemuthianum. [ABSTRACT FROM AUTHOR]

Copyright of Agronomía & Ambiente is the property of Universidad de Buenos Aires. Facultad de Agronomia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Ry adg allele is widely used by breeders to confer extreme resistance to all strains of PVY. However, the necrotic strain has increased recombination resulting in recent considerable losses in productivity. Thus far, not all necrotic recombinant strains of PVY have been tested for their reaction to the Ry gene. The objective of this study was to identify potato clones carrying the resistant allele and to assess their reaction to the following recombinant strains: NTN (PVY NTN), Wilga (PVY N-Wi), and "curly top" (PVY E). Advanced clones from the potato breeding program at Universidade Federal de Lavras were evaluated through a specific molecular marker for the Ry adg allele. The clones carrying the resistance allele were grafted on tobacco plants infected with necrotic recombinant strains of PVY. The clones carrying the allele for resistance to PVY were not infected with any of the recombinants during the grafting test. These results confirm that resistance to necrotic recombinant strains has not yet been overcome and that the Ry adg allele also confers resistance to the three recombinant strains tested.

The objectives of this study were to evaluate the possibility of selecting anthracnose resistant common bean plants using detached primary leaves in partially controlled environment of a greenhouse and identify differences in the reaction of genotypes to anthracnose. The common bean cultivars Ouro Negro, OuroVermelho, ManteigãoFosco 11, Rudá, Rudá-R, VP8, BRSMG Madrepérola, Pérola, MeiaNoite and BRSMG Talismãwere characterizedfor resistance to the races 65, 81 and 453 of Colletotrichum lindemuthianum and the method of detached primary leaves was compared to the method with the traditional inoculation of plants at the phenological stage V2. The lines Rudá, Rudá-R and Pérola were inoculated with the races 65 and 453 of C. lindemuthianum, aiming to assess the rate of coincidence of anthracnose severity by both inoculation methods. In general, the two methods presented similar results for the reaction of the cultivars. The use of detached primary leaves of common bean plants in the partially controlled environment was feasible for selection of plants resistant to anthracnose and has the advantages of low-needed infrastructure and reduction of resources, space and time.