Desarrollo del plantas de transgenicas frijol por el gen de la cápside del virus del mosaico dorado (BGMV)

Programa Cooperativo Regional de Frijol para Centroamérica, México y el Caribe (PROFRIJOL)Cooperación Suiza para el Desarrollo (COSUDE)Centro Internacional de Agricultura Tropical (CIAT)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

La organización y función del genoma del virus del mosaico dorado del frijol

Programa Cooperativo Regional de Frijol para Centroamérica, México y el Caribe (PROFRIJOL)Cooperación Suiza para el Desarrollo (COSUDE)Centro Internacional de Agricultura Tropical (CIAT)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

Bean Golden Mosaic: Research Advances

El frijol (Phaseolus vulgaris L.) es una de las fuentes de proteina (15-35%) y calorías (ca. 340 caI./100 gr) más importantes en la América Latina. En esta región, centro de origen de esta especie, se producen más de cuatro millones de toneladas de frijol al año, lo cual equivale al 88% de la semilla de frijol producida en las regiones tropicales del mundo. Brasil, el mayor productor de frijol del mundo, posee un consumo per capita de cerca de 20 kg/año. En America Central, el frijol es igualmente importante, siendo consumido en la mayoría de los países centroamericanos hasta tres veces por día. Proporcionalmente, en la America Central se cultiva el doble del área que en Brasil, relativo a sus extensiones territoriales. El frijol es también producido en islas del Caribe, tales como Cuba (ca. 26.000 TM), Haití (56.000 TM) y República Dominicana (55.000 TM) según datos de 1990 (CIAT). México, el segundo productor de frijol en la America Latina, consume aproximadamente 1.2 millones de toneladas métricas de frijol al año. A pesar de que México cultiva cerca de 1.800.000 hectáreas de frijol, la demanda interna no es satisfecha en algunos años dado la baja productividad del cultivo. Esta baja productividad relativa del frijol, no solo en México sino también en el resto de la América Latina (700 kg/ha vs. 1.600 kg/ha en los Estados Unidos), es una consecuencia de los múltiples problemas bióticos y abióticos que inciden en el cultivo, en el trópico Americano. Es precisamente en las regiones productoras de frijol situadas en climas cálidos, de altitud baja a intermedia (0-1200 m.s.n.m), donde el mosaico dorado del frijol alcanza su mayor incidencia.The common bean (Phaseolus vulgaris L.) is an important source of protein and calories in Latin America. In this region, the center of origin of this legume species, over 4 million tons of dry beans are produced per year. Nevertheless, many Latin American countries, including two of the largest producers of beans in the world, Brazil and Mexico, have to import beans to meet internal demand. This shortage of beans is related to the low productivity of this crop in Latin America (700 kg /ha vs. 1,600 kg/ ha average in the USA). The low productivity in the main bean production regions of tropical America is associated to the incidence of several biotic and abiotic constraints. Among the biotic constraints, bean golden mosaic virus is undoubtedly the main bean production problem in the lowland tropics, particularly, during the dry seasons of the year.Programa Cooperativo Regional de Frijol para Centroamérica, México y el Caribe (PROFRIJOL)Cooperación Suiza para el Desarrollo (COSUDE)Centro Internacional de Agricultura Tropical (CIAT)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

Detection of dsRNA from Cleistothecia and Conidia of the Grape Powdery Mildew Pathogen, Uncinula Necator

Double-stranded RNA species ranging in molecular weight from 0.95 to 6.3 × 106 were detected in grapevines in New York. We recently showed that two of the species (Mr = 5.3 and 4.4 × 106) are associated with rupestris stem pitting disease. In this report, we show that the other eight detectable dsRNA species are associated with the powdery mildew fungus, Uncinula necator. These dsRNAs associated with the powdery mildew fungus were previously detected in leaves and epidermal stem tissue of grapevines infected with powdery mildew. The same dsRNA species were also detected from extracts of isolated cleistothecia and conidia of U. necator devoid of plant tissue. Isometric and rigid rodlike particles were observed in single cleistothecia preparations when examined under transmission electron microscopy

Detection of dsRNA in Grapevines Showing Symptoms of Rupestris Stem Pitting Disease and the Variabilities Encountered

Rupestris stem pitting (rSP), a graft-transmissible grapevine disease, can be identified only by its reaction (pitted wood) on inoculated Vitis rupestris ‘St. George.’ DsRNA was extracted from grapevines from California and Canada that indexed positive for rSP on St. George. Two distinct dsRNA species (B and C) (Mr = 5.3 × 106 and 4.4 × 106, respectively) were detected from the stem tissue of rSP-positive samples. Although similar dsRNA species (B and C) were detected in extracts of grapevines from New York, the association of dsRNA B and C with rSP in New York samples was not consistent. Also, eight different dsRNAs, known to be associated with the powdery mildew fungus, Uncinula necator, were detected in leaves of New York samples. In New York, the dsRNAs were not observed in leaves or stem samples collected from June through late August during the 1988 and 1989 growing seasons, suggesting that dsRNA detection in the grape tissue is variable throughout the season. We suggest that dsRNA species B and C are associated with rSP disease. The inconsistent results with New York samples are discussed

Sequence Changes in Six Variants of Rice Tungro Bacilliform Virus and Their Phylogenetic Relationships

The DNA of three biological variants, G1, Ic and G2, which originated from the same greenhouse isolate of rice tungro bacilliform virus (RTBV) at the International Rice Research Institute (IRRI), was cloned and sequenced. Comparison of the sequences revealed small differences in genome sizes. The variants were between 95 and 99% identical at the nucleotide and amino acid levels. Alignment of the three genome sequences with those of three published RTBV sequences (Phi-1, Phi-2 and Phi-3) revealed numerous nucleotide substitutions and some insertions and deletions. The published RTBV sequences originated from the same greenhouse isolate at IRRI 20, 11 and 9 years ago. All open reading frames (ORFs) and known functional domains were conserved across the six variants. The cysteine-rich region of ORF3 showed the greatest variation. When the six DNA sequences from IRRI were compared with that of an isolate from Malaysia (Serdang), similar changes were observed in the cysteine-rich region in addition to other nucleotide substitutions and deletions across the genome. The aligned nucleotide sequences of the IRRI variants and Serdang were used to analyse phylogenetic relationships by the bootstrapped parsimony, distance and maximum-likelihood methods. The isolates clustered in three groups: Serdang alone; Ic and G1; and Phi-1, Phi-2, Phi-3 and G2. The distribution of phylogenetically informative residues in the IRRI sequences shared with the Serdang sequence and the differing tree topologies for segments of the genome suggested that recombination, as well as substitutions and insertions or deletions, has played a role in the evolution of RTBV variants. The significance and implications of these evolutionary forces are discussed in comparison with badnaviruses and caulimoviruses