The development of durable resistance to broomrape (Orobanche cumana Wallr.) in sunflower (Helianthus annuus L.) requires detailed characterization of the genetic and physiological bases of resistance. The objective of the present study was to map the resistance gene accurately, and to characterize the mechanism of resistance to broomrape observed in a sunflower inbred line (PHSC1102). PHSC1102, which was consistently resistant against race F and race G populations of broomrape, was crossed with PHSC1201, which was susceptible to races F and G. A mapping population of 150 F 2 genotypes was phenotyped by evaluating F 2:3 families for resistance to broomrape races F GV and G TK . The use of single nucleotide polymorphism (SNP) markers mapped the Or SII gene to Linkage Group 4 (LG4) of the sunflower genome. Minirhizotron and histological studies of the resistant line revealed that the attachment of broomrape to host roots was similar in both the resistant and susceptible lines and that the resistance was observed at a late stage (i.e., after tubercle development). Interestingly, the resistance of the PHSC1102 line was associated with the production of phenolic compounds, which were hypothesized to restrict the parasite's growth. This research provides novel and valuable information about the host-parasite interactions between sunflower and broomrape.Abbreviations: DAB, 3,3-diaminobenzidine; LG, linkage group; LOD, logarithm of odds; PBS, phosphate-buffered saline; PCR, polymerase chain reaction; QTL, quantitative trait loci; SNP, single nucleotide polymorphism; TBO, toluidine blue O.
Verticillium wilt and leaf mottle of sunflower, caused by the fungus Verticillium dahliae (Vd) has become a major constraint to sunflower oil production in temperate European countries. Information about Vd from sunflower is very scarce despite genetics, molecular traits and pathogenic abilities of fungal strains affecting many other crops being widely known. Understanding and characterizing the diversity of Vd populations in those countries where sunflowers are frequent and severely affected by the fungus are essential for efficient breeding for resistance. In this study, we have analyzed genetic, molecular and pathogenic traits of Vd isolates affecting sunflower in European countries. When their genetics was investigated, almost all the isolates from France, Italy, Spain, Argentina, and Ukraine were assigned to vegetative compatibility group (VCG) 2B. In Bulgaria, Turkey, Romania, and Ukraine, some isolates were assigned to VCG6, but some others could not be assigned to any VCG. Genotyping markers used for Vd affecting crops other than sunflower showed that all the isolates were molecularly identified as race 2 and that markers of defoliating (D) and non-defoliating (ND) pathotypes distinguished two well-differentiated clusters, one (E) grouping those isolates from Eastern Europe and the other (W) all those from the Western Europe and Argentina. All the isolates in cluster W were VCG2B, while the isolates in cluster E belonged to an unknown VCG or to VCG6. When the host range was investigated in the greenhouse, the fungus was highly pathogenic to artichoke, showing the importance of farming alternatives in the management of Verticillium attacks. Sunflower genotypes were inoculated with a selection of isolates in two experiments. Two groups were identified, one including the isolates from Western Europe, Argentina, and Ukraine, and the other including isolates from Bulgaria, Romania, and Turkey. Three pathogenic races were differentiated: V1, V2-EE (Eastern Europe) and V2-WE (Western Europe). Similarly, three differentials are proposed for race identification: HA 458 (universal susceptible), HA 89 (resistant to V2-EE, susceptible to V2-WE) and INRA2603 (susceptible to V2-EE, resistant to V2-WE). The diversity found in Vd affecting sunflower must be taken into account in the search for resistance to the pathogen for European environments of sunflower production.
Se expone el caso de un hombre de 20 años, que consultó a urgencias por cuadro de 2 horas de parestesias y pérdida de la fuerza muscular en miembros inferiores, hasta incapacidad completa para incorporarse desde una silla. Cinco episodios similares, matutinos, leves, de corta duración, con resolución espontánea, durante los últimos dos meses. Cuatro meses antes había estado presentando palpitaciones, pérdida de 12 kilos de peso con polifagia, sensibilidad al calor, hiperdefecación y temblor fino en manos. Se documentó y corrigió hipokalemia. Se confirmó enfermedad de Graves dando tratamiento con propanolol y 20mCi de I131. La parálisis periódica hipokalémica tirotóxica (PPHT) es una emergencia y puede presentarse desde debilidad muscular de predominio proximal hasta una parálisis completa con riesgo de muerte secundario a hipokalemia severa. El diagnóstico se confirma con la presencia de signos clínicos y/ó bioquímicos de tirotoxicosis asociados a hipokalemia. En la PPHT, hay un incremento de actividad de la bomba Na K – ATPasa dado por un aumento en la estimulación beta adrenérgica asociado a un exceso de hormona tiroidea. Los factores precipitantes de crisis de PPHT mas frecuentes son la alta ingesta de carbohidratos y el ejercicio extenuante, aunque existen muchos otros más. Es importante la pesquisa de hipertiroidismo en individuos con parálisis ó debilidad muscular e hipokalemia. Ésta condición se ha descrito principalmente en hombres asiáticos, pero debe ser considerada también en nuestro medio.
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