Two virus isolates, T1 and T2, causing necrotic spots on leaves and stems of pepper and tomato, respectively, were isolated in the La Joya valley, Arequipa, Peru, in 2010. These two isolates were inoculated to differential hosts for tospoviruses and showed differential fitness: T1 induced necrotic local lesions in Vigna unguiculata, whereas T2 produced only chlorotic spots. The complete nucleotide sequence of the small (S) RNA from T2 and 1863 bp of the S RNA from T1 were determined. The deduced N protein sequence showed high amino acid identity (97%) between the isolates, indicating that the T1 and T2 are isolates of the same virus. Sequence comparisons indicated that the amino acid sequence of the N protein shared 53.49-87.98% identity with known American tospoviruses. Phylogenetic analysis of both the NSs and N proteins revealed that this new tospovirus belongs to the American group. We conclude that this tospovirus should be considered a member of a new species. The name Pepper necrotic spot virus (PNSV) is proposed.
Pseudomonas fluorescens F113 is motile by means of type b flagella. Analysis of the region encoding the synthesis of the flagellar filament has shown a transcriptional organization different from that of type a flagella. Additionally to the promoters driving fliC, fliD, and fleQ expression, we have found promoters upstream of the flaG gene and the fliST operon. These promoters were functional in vivo. Both promoters have been mapped and appear to be dependent on the vegetative sigma factor and independent of FleQ, the master regulator of flagellum synthesis.Pseudomonads are ubiquitous bacteria that can adapt to different lifestyles, with species that are either saprophytic or pathogenic for plants and animals. Motility is an important trait for pseudomonads, and it has been shown to be involved in rhizosphere colonization (7,13,14,18), biofilm formation (9,20,27), and pathogenesis in plant (10, 22) and animal (4) models. Flagellar biosynthesis in pseudomonads is regulated in a hierarchical way, with the transcriptional activator fleQ on top of the regulatory cascade (2, 8). Besides, the alternative sigma factors encoded by fliA and rpoN are required for flagellum assembly (25,26). The regulation of flagellar biosynthesis has been analyzed using DNA microarrays and Pseudomonas aeruginosa PAK (12), which contains type a flagella (24). Other pseudomonads, like Pseudomonas fluorescens F113 or P. aeruginosa PAO1, contain type b flagella and are characterized by different syntenies in the region encoding the formation of the flagellar filament (7,12,24). In type b strains, this region contains fliC, encoding type b flagellin; flaG, encoding a protein of unknown function implicated in filament length (7); fliD, encoding the flagellar-cap protein (3); fliS, encoding a FliC chaperone required for flagellin export and assembly (7); fliT, encoding a protein of unknown function required for full motility and rhizosphere colonization in P. fluorescens F113 (7); fleQ (2, 8), encoding the master regulatory protein; and fleSR, encoding a two-component system required for flagellar biosynthesis (23).Analysis of the transcriptional organization of a region implicated in the synthesis of the flagellar filament in P. fluorescens F113. In order to establish the transcriptional organization of the fliC-fleQ region of Pseudomonas fluorescens F113, the upstream regions of the fliC, flaG, fliS, fliT, and fleQ genes were amplified and cloned into the reporter vector pMP220 to form transcriptional fusions with a promoterless lacZ gene. These constructs were introduced into strain F113 by triparental mating, and -galactosidase activity was tested (19). Substantial activity was shown for the regions upstream of all genes (125 to 350 Miller units), except the region upstream of the fliT gene (Ͻ5 Miller units) (see Fig. S1 in the supplemental material). Previous studies of other pseudomonads have shown the existence of promoters upstream of the fliC, fliD, and fleQ genes. To our knowledge, no promoters have been found upstream of the flaG or...
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