ABSTRACT. Xylella fastidiosa inhabits the plant xylem, a nutrient-poor environment, so that mechanisms to sense and respond to adverse environmental conditions are extremely important for bacterial survival in the plant host. Although the complete genome sequences of different Xylella strains have been determined, little is known about stress responses and gene regulation in these organisms.

ABSTRACT. Xylella fastidiosa inhabits the plant xylem, a nutrient-poor environment, so that mechanisms to sense and respond to adverse environmental conditions are extremely important for bacterial survival in the plant host. Although the complete genome sequences of different Xylella strains have been determined, little is known about stress responses and gene regulation in these organisms.

ABSTRACT. Several isolates of a novel begomovirus were characterized from tomato samples collected in northern Uruguay exhibiting disease symptoms associated with Bemisia tabaci infestations. Analysis of full-length sequences of DNA-A and DNA-B components revealed the presence of a new begomovirus with the typical genome organization of a New World begomovirus, for which the name tomato rugose yellow leaf curl virus (ToRYLCV) is proposed. A high degree of nucleotide sequence diversity was found for both components, suggesting the presence of a diverse virus population.

RESUMEN En los últimos años los enfoques participativos para el desarrollo, la investigación e innovación en el sector agrario han ido ganando terreno en la búsqueda de respuestas más adaptadas a las necesidades de los productores. Una de las formas de dichos enfoques ha sido la investigación participativa (IP), en la cual investigadores y productores analizan y definen los temas a investigar y producen nuevos conocimientos al compartir perspectivas y experiencias, promoviendo fundamentalmente un aprendizaje social.

RESUMEN La organización de los sistemas agrícolas requiere la verificación de la identidad y pureza genética de los cultivares. El aumento en el número de cultivares de soja a ser evaluados y su estrecha base genética dificulta su identificación mediante evaluación de descriptores fenotípicos. La Unión Internacional para la Protección de las Obtenciones Vegetales (UPOV) ha reconocido la utilidad de marcadores moleculares asociados con caracteres fenotípicos descriptivos.

ABSTRACT. An analysis of a series of five peptides composed of various portions of the pleurocidin (Plc) sequence identified a l2-amino acid fragment from the C-terminus of Plc, designated Plc-2, as the smallest fragment that retained a antimicrobial activity comparable to that of the parent compound. MIC tests in vitro with low-ionic-strength medium showed that Plc-2 has potent activity against Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus but not against Enterococcus faecalis.