Complete genome and molecular characterization of a putative novel citrivirus from Rudbeckia sp.

We identified a tentative novel positive-strand RNA virus from Rudbeckia sp., namely, Rudbeckia citrivirus A (RuCVA). The complete genome sequence of the novel virus was 8821 nucleotides in length, excluding the poly(A) tail. It has three open reading frames (ORFs): a putative polyprotein, a movement protein, and a coat protein. Phylogenetic analysis showed that the virus was more closely related to Citrus leaf blotch virus isolates and unassigned citriviruses. The sequence identity of the virus with other citriviruses was lower than 56.9% at the complete nucleotide sequence level. For each ORF, the sequence identity was lower than 64.2% at the nucleotide level and 67.8% at the amino acid level. These results satisfied the species demarcation criteria for Betaflexiviridae. Therefore, we suggest that RuCVA is a novel member of the genus Citrivirus.

Complete genome sequence of a putative novel cytorhabdovirus isolated from Rudbeckia sp.

Through high-throughput RNA sequencing, we discovered a putative new cytorhabdovirus in the seeds of Rudbeckia sp., which we have tentatively named "rudbeckia virus 1" (RudV1). Its complete 12,502-nt genomic sequence contains five open reading frames (ORFs): ORF1 (putative nucleocapsid protein, N), ORF2 (putative phosphoprotein, P), ORF3 (putative cell-to-cell movement protein, P3), ORF4 (putative matrix protein, M), and ORF5 (putative RNA-dependent RNA polymerase, L). BLASTp searches showed that ORF1, ORF3, ORF4, and ORF5 of RudV1 are most closely related to the corresponding proteins of Tagetes erecta virus 1 (a putative member of the genus Cytorhabdovirus) with 33.87% (88% query coverage), 55.98% (89% query coverage), 35.33% (94% query coverage), and 57.75% (98% query coverage) sequence identity at the amino acid level, respectively. Phylogenetic analysis and pairwise comparisons indicated that RudV1 is a novel member of the genus Cytorhabdovirus within the family Rhabdoviridae.

Interpreting spatial variation in ozone symptoms shown by cutleaf cone flower, Rudbeckia laciniata L.

Visible injury caused by ozone is recorded every year in native plant species growing in Great Smoky Mountains National Park (USA). One of the most sensitive species, cutleaf coneflower (Rudbeckia laciniata L.), shows great variation in symptoms between and within populations but the causes of this variation and its ecological significance are currently unknown. This paper presents data relating to genetic variation, ozone concentrations, stomatal conductance and light (PAR) within populations. The data show that populations differ in genetic diversity, one consisting of only three genets while another was very diverse. In the former population, symptoms varied greatly within a single genet, pointing to a large micro-environmental influence. Measurements of ozone, stomatal conductance and PAR within plant canopies suggest that variation in symptom expression is unlikely to be due to differences in ozone flux and more likely to be due to variation in light. The variation in visible symptoms raises the question of what bioindicators actually indicate, and it suggests that symptoms should be interpreted with great caution until the underlying causes of that variation are fully understood.