Metodos para el manejo de enfermedades de pastos tropicales en Sur America

Durante la decada pasada, varias enfermedades de plantas forrajeras tropicales ocasionan perdidas considerables en America del Sur. Casi todas lasenfermedades han ocurrido en praderas de leguminosas nativas promisorias, en regiones de produccion de pastos, mientras que las gramineas introducidas de Africa han tenido pocos problemas de enfermedades. El significado de esta diferencia es discutible. El posible manejo de enfermedades en praderas tropicales incluye control quimico y biologico, control natural a traves de saneamiento, asociacion estrategica, manejo de praderas y resistencia. El saneamiento a traves de la quema y asociacion estrategica ha mostrado potencial para el manejo de enfermedades de plantas forrajeras tropicales. Aunque la resistencia se considera como el metodo de manejo de enfermedades mas practico, su origen parece estar modificado por las caracteristicas de los ecosistemas de las praderas tropicales en America del Sur. (Extracto

A world list of fungal diseases of tropical pasture species

Esta lista mundial de enfermedades causadas por hongos en las plantas forrajeras tropicales recopila muchos registros ineditos de International Mycological Institute, registros personales del autor y registros provenientes de exhaustivas busquedas de informacion. Esta lista incluye enfermedades registradas en 429 especies de 37 generos de leguminosas (por ejemplo Aeschynomene, Centrosema, Desmodium, Leucaena, Macroptilium y Stylosanthes) y en 667 especies de 31 generos de gramineas (por ejemplo, Andropogon, Brachiaria, Digitaria, Panicum, Paspalum, Pennisetum y Setaria), su distribucion y una bibliografia exhaustiva de mas de 300 referencias. Siendo esta la primera lista de enfermedades criptogamicas en las plantas forrajeras tropicales, seguramente sera una referencia valiosa para los especialistas en pasturas y funcionarios de cuarentena en los paises tropicales, especialmente en aquellos donde actualmente se implementan programas de introduccion de germoplasma forrajero. (RA

Enzymatic Regulation of Protein-Protein Interactions in Artificial Cells

Membraneless organelles are important for spatial organization of proteins and regulation of intracellular processes. Proteins can be recruited to these condensates by specific protein–protein or protein–nucleic acid interactions, which are often regulated by post-translational modifications. However, the mechanisms behind these dynamic, affinity-based protein recruitment events are not well understood. Here, a coacervate system that incorporates the 14-3-3 scaffold protein to study enzymatically regulated recruitment of 14-3-3-binding proteins is presented, which mostly bind in a phosphorylation-dependent manner. Synthetic coacervates are efficiently loaded with 14-3-3, and phosphorylated binding partners, such as the c-Raf pS233/pS259 peptide (c-Raf), show 14-3-3-dependent sequestration with up to 161-fold increase in local concentration. The c-Raf domain is fused to green fluorescent protein (GFP-c-Raf) to demonstrate recruitment of proteins. In situ phosphorylation of GFP-c-Raf by a kinase leads to enzymatically regulated uptake. The introduction of a phosphatase into coacervates preloaded with the phosphorylated 14-3-3-GFP-c-Raf complex results in a significant cargo efflux mediated by dephosphorylation. Finally, the general applicability of this platform to study protein–protein interactions is demonstrated by the phosphorylation-dependent and 14-3-3-mediated active reconstitution of a split-luciferase inside artificial cells. This work presents an approach to study dynamically regulated protein recruitment in condensates, using native interaction domains.</p

Stem gall nematode on Desmodium ovalifolium in Colombia

A stem gall nematode is reported for the first time on the promising tropical pasture legume Desmodium ovalifolium CIAT 350 in Colombia. Stem galling was usually associated with damage caused by animal trampling. The nematode has been identified as a new genus of the family Anguinidae

Variation in reaction to anthracnose within native Stylosanthes capitata populations in Minas Gerais, Brazil

Native populations of Stylosanthes capitata, a promising perennial pasture legume in tropical America, were evaluated for their reaction to a virulent widespread race of Colletotrichum gloeosporioides. Considerable variation in anthracnose reaction among progenies from individual plants, among plants from the same site, and between populations from the same and different sites in Minas Gerais, Brazil, was found. The greatest diversity for anthracnose reaction among progeny was shown by population Diamantina B (Shannon Index of Diversity h = 0.39), whereas the least was found in Mendanha B (h = 0.17). Although the majority of progenies were susceptible, highly resistant progenies were found in all populations. Results suggest that diversity in anthracnose resistance within native S. capitata populations contributes to their persistence in the presence of virulent C. gloeosporioides and emphasize the importance of maintaining diversity in improved S. capitata pastures in agroecosystems where C. gloeosporioides is endemic

Reaction of Desmodium species and other tropical pasture legumes to the root-knot nematode Meloidogyne javanica

The detection of the root-knot nematode, Meloidogyne javanica, as a pathogen of Desmodium spp. in Colombia, is the first reported case in South Aemerica. In the field, promising pasture legumes D. gyroides, D. heterocarpon and D. ovalifolium were severely damaged, while adjacent stands of Centrosema, Leucaena, Stylosanthes and Zornia spp. were not affected. In greenhouse trials with 38 tropical pasture legumes, only 13 accessions, including 10 of Desmodium spp. were susceptible. Accessions of D. distortum, D. heterophyllum, Leucaena leucocephala, Pueraria phaseoloides, Stylosanthes spp. including 6 Australian commercial cultivars, and Zornia latifolia were resistant. Although M. javanica has a narrow pasture legume host range and a very limited distribution throughout pasture evaluation sites, its pathogenicity to promising Desmodium spp. merits future surveys to determine its occurrence in the major pasture regions of tropical South America

Diseases of Cassia species--a review

A wide range of fungi, two bacteria and several viruses and nematodes have been recorded throughout the tropics on a group of Cassia species defined as taxonomically and geographically related to Cassia rotundifolia. Although limited information was found on the relative importance of these pathogens, the fungi Alternaria cassiae, Corynespora cassiicola, Phomopsis cassiae, Pseudocercospora nigricans, Pseudoperonospora cassiae and Ravenelia berkeleyii and the viruses Cassia Mild Mosaic, Cassia Yellow Blotches and Cassia Yellow Blotch are considered the most serious. Specific recommendations are made to evaluate the reaction of C. rotundifolia cv. Wynn to these pathogens. The attention of Australian pasture scientists is drawn to recent plans to develop mycoherbicides for controlling pantropical Cassia weeds and the implications of their use in South-east Asia and the south-west Pacific

Diseases of Desmodium species - A review

Fungal pathogens representing 36 genera and over 70 species, one bacterium, mycoplasma-like-organisms, at least six viruses, five races of root-knot nematodes and six other nematodes have been recorded on 18 Desmodium species of agronomic interest throughout tropical regions. Although limited information precludes a definitive discussion of the relative importance of many diseases, two fungal diseases — Synchytrium desmodii and Phanerochaeta salmonicolor — causing wart and pink disease, respectively, of Desmodium ovalifolium and several nematode pathogens including races of the root-knot nematodes Meloidogyne arenaria, M. hapla, M. incognita and M. javanica of Desmodium species and stem gall nematode Pterotylenchus cecidogenus of D. ovalifolium are presently regarded as important pathogens. Awareness of the range and distribution of fungal pathogens recorded on Desmodium species as well as the existence of potentially seed-borne bacteria and potyviruses is regarded as essential for preventing global transmission of these pathogens and serious disease problems in the future. This is the first time that the great diversity of information available on diseases of Desmodium species has been summarised. It should provide a useful reference for many tropical pasture scientists