Characteristics of Beet Soilborne Mosaic Virus, a Furo-like Virus Infecting Sugar Beet

Beet soilborne mosaic virus (BSBMV) is a rigid rod-shaped virus transmitted by Polymyxa betae. Particles were 19 nm wide and ranged from 50 to over 400 nm, but no consistent modal lengths could be determined. Nucleic acids extracted from virions were polyadenylated and typically separated into three or four discrete bands of variable size by agarose-formaldehyde gel electrophoresis. RNA 1 and 2, the largest of the RNAs, consistently averaged 6.7 and 4.6 kb, respectively. The sizes and number of smaller RNA species were variable. The molecular mass of the capsid protein of BSBMV was estimated to be 22.5 kDa. In Northern blots, probes specific to the 3´ end of individual beet necrotic yellow vein virus (BNYVV) RNAs 1–4 hybridized strongly with the corresponding BNYVV RNA species and weakly with BSBMV RNAs 1, 2, and 4. Probes specific to the 5´ end of BNYVV RNAs 1–4 hybridized with BNYVV but not with BSBMV. No cross-reaction between BNYVV and BSBMV was detected in Western blots. In greenhouse studies, root weights of BSBMV-infected plants were significantly lower than mock-inoculated controls but greater than root weights from plants infected with BNYVV. Results of serological, hybridization, and virulence experiments indicate that BSBMV is distinct from BNYVV. However, host range, capsid size, and the number, size, and polyadenylation of its RNAs indicate that BSBMV more closely resembles BNYVV than it does other members of the genus Furovirus

Tobamovirus and Dianthovirus Movement Proteins Are Functionally Homologous

AbstractThe movement proteins (MPs) of tobacco mosaic tobamovirus (TMV) and red clover necrotic mosaic dianthovirus (RCNMV) enlarge plasmodesmata size exclusion limits, transport RNA from cell to cell, and bind nucleic acids in vitro. Despite these functional similarities, they have no sequence homology. However, they do appear to have similar secondary structures. We have used transgenic plants expressing either the TMV MP or the RCNMV MP, and a chimeric TMV that encodes the RCNMV MP as its only functional MP gene, to demonstrate that the MPs of TMV and RCNMV are functionally homologous. Further, both TMV and RCNMV can act as helper viruses to allow the cell-to-cell movement of the heterologous movement-defective viruses. These data support the conclusion that, despite other differences, such as particle morphology, host range, and sequence, TMV and RCNMV share a common mechanism for cell-to-cell movement

Diversidade de Gluconacetobacter diazotrophicus isolada de plantas de cana-de-açúcar cultivadas no Brasil Diversity of Gluconacetobacter diazotrophicus isolated from sugarcane plants cultivated in Brazil

O objetivo deste trabalho foi avaliar a diversidade da população de Gluconacetobacter diazotrophicus oriunda de cultivares de cana-de-açúcar (Saccharum spp.) de diferentes regiões e bancos de germoplasma. O estudo foi realizado com 123 isolados, obtidos de folhas, colmos e raízes de 80 espécies e híbridos de cana-de-açúcar, procedentes de diferentes países e mantidos em coleções de germoplasma nos Estados da Bahia e Rio de Janeiro. Foram utilizados cinco isolados obtidos de plantas de café (Coffea arabica), dois de abacaxi (Ananas comosus) e um de Pennisetum purpureum e mais 10 estirpes com padrões eletroforéticos distintos, após o uso de enzimas comuns do metabolismo microbiano (MLEE). O agrupamento obtido por meio da técnica de imunoadsorção com enzima acoplada (ELISA) sugere que as variações expressas pelos isolados não estão relacionadas com a espécie de planta, a variedade de cana-de-açúcar, a origem geográfica, a parte da planta de onde os isolados foram obtidos e o tempo de amostragem. Altas doses de nitrogênio levaram à diminuição da diversidade de G. diazotrophicus.<br>The objective of this study was to evaluate the diversity of Gluconacetobacter diazotrophicus isolates from different sugarcane (Saccharum spp.) varieties. This study was developed using 123 strains from the internal tissues of stems and roots, isolated from 80 species and hybrids of sugarcane, originated from different countries and maintained in two germoplasm collections localized in Bahia and Rio de Janeiro States. Five isolates obtained from coffee plants (Coffea arabica), two from pineapple (Ananas comosus), one from Pennisetum purpureum and 10 strains, which present different electrophoretic patterns, were used in the comparison. Cluster analysis of enzyme-linked immunosorbent assay (ELISA) results suggested that variations were not correlated with the plant species, sugarcane variety, geographic origin, parts of plants nor with sampling time. High nitrogen doses lowered the diversity of G. diazotrophicus