Takamichi Nijo

First Complete Genome Sequence of Cherry virus A

ABSTRACT The 5′-terminal genomic sequence of Cherry virus A (CVA) has long been unknown. We determined the first complete genome sequence of an apricot isolate of CVA (7,434 nucleotides [nt]). The 5′-untranslated region was 107 nt in length, which was 53 nt longer than those of known CVA sequences.

Complete Genome Sequence of Alternanthera mosaic virus, Isolated from Achyranthes bidentata in Asia

ABSTRACT Alternanthera mosaic virus (AltMV) infecting Achyranthes bidentata was first detected in Asia, and the complete genome sequence (6,604 nucleotides) was determined. Sequence identity analysis and phylogenetic analysis confirmed that this isolate is the most phylogenetically distant AltMV isolate worldwide.

First report of bacterial leaf blight on cosmos (Cosmos bipinnatus Cav.) caused by Pseudomonas cichorii in Japan

Since 2006, a commercial grower in Japan has noted a leaf blight symptom on potted cosmos plants grown in a field. In August 2012, a Pseudomonas-like bacterium was isolated from the symptomatic leaves and found to cause the same symptom on cosmos seedlings after inoculation. On the basis of bacteriological and phylogenetic analyses, the causative bacterium was identified as Pseudomonas cichorii. This is the first report of bacterial leaf blight on cosmos caused by P. cichorii in Japan.

Functional characterization of the principal sigma factor RpoD of phytoplasmas via an in vitro transcription assay

Phytoplasmas (class, Mollicutes) are insect-transmissible and plant-pathogenic bacteria that multiply intracellularly in both plants and insects through host switching. Our previous study revealed that phytoplasmal sigma factor rpoD of OY-M strain (rpoDOY) could be a key regulator of host switching, because the expression level of rpoDOY was higher in insect hosts than in plant hosts. In this study, we developed an in vitro transcription assay system to identify RpoDOY-dependent genes and the consensus promoter elements. The assay revealed that RpoDOY regulated some housekeeping, virulence, and host–phytoplasma interaction genes of OY-M strain. The upstream region of the transcription start sites of these genes contained conserved –35 and –10 promoter sequences, which were similar to the typical bacterial RpoD-dependent promoter elements, while the –35 promoter elements were variable. In addition, we searched putative RpoD-dependent genes based on these promoter elements on the whole genome sequence of phytoplasmas using in silico tools. The phytoplasmal RpoD seems to mediate the transcription of not only many housekeeping genes as the principal sigma factor, but also the virulence- and host-phytoplasma interaction-related genes exhibiting host-specific expression patterns. These results indicate that more complex mechanisms exist than previously thought regarding gene regulation enabling phytoplasmas to switch hosts.

Construction of an infectious cDNA clone of radish mosaic virus, a crucifer-infecting comovirus.

Radish mosaic virus (RaMV) is a crucifer-infecting comovirus that has been detected worldwide. Here, we report the successful construction of a full-length infectious cDNA clone of RaMV. The full-length cDNA clones corresponding to RNA1 and RNA2 of a Japanese isolate of RaMV were cloned into the pBlueScript plasmid or the binary vector pCAMBIA1301 downstream of the cauliflower mosaic virus 35S promoter. Mechanical inoculation or agroinoculation of Nicotiana benthamiana with these vectors resulted in systemic RaMV infections causing symptoms similar to those caused by the wild-type parental virus. The presence of progeny virus was verified by western blot analysis and electron microscopy.

Phytoplasma-conserved phyllogen proteins induce phyllody across the Plantae by degrading floral MADS domain proteins

Phyllogen, a bacterial virulence factor, induced phyllody in various eudicot species, and had broad-spectrum degradation activity on MADS domain transcription factors of plants, suggesting phyllogen universally functions in plants.

Complete Genome Sequence of a Lily virus X Isolate from Japan

ABSTRACT The complete genome sequence of Lily virus X (LVX), which infects lilies, was determined for the first time from lilies in Japan. As with previous reports, the genome of the Japanese LVX isolate lacked an AUG start codon for the triple gene block protein 3-like region.

First report of a Neofusicoccum sp. causing stem-end rot of mango

In November 2013, a Japanese fruit importer noted a large, black, water-soaked lesion at the stem end of a mango from the Philippines. A fungus was isolated from the lesion and identified as a Neofusicoccum sp. closely related to Neofusicoccum sp. karanda, based on morphological and phylogenetic analyses. The isolated fungus caused black, water-soaked lesions on mango after back-inoculation. The symptoms were also very similar to those caused by Lasiodiplodia theobromae, which causes stem-end rot on mangos in Japan. Therefore, we propose the addition of Neofusicoccum sp. closely related to Neofusicoccum sp. karanda as a cause of stem-end rot on mango.

First report of bacterial black spot on calanthe (Calanthe spp.) caused by Burkholderia andropogonis in Japan

In July 2013, black spots were observed on leaves of calanthe in a flowerbed of a park in Tokyo, Japan. The spots were circular to oval and often accompanied by a yellow halo. A bacterium was isolated from the lesions and was found to cause the same symptoms on calanthe leaves after inoculation. Based on phylogenetic and bacteriological analyses, the causal bacterium was identified as Burkholderia andropogonis. This is the first report of bacterial black spot on calanthe caused by B. andropogonis in Japan.