Seasonal stream habitat of adult Sakhalin taimen,Parahucho perryi,in the Bekanbeushi River system,eastern Hokkaido,Japan

Behavioural tracking of endangered adult Sakhalin taimen (Parahucho perryi) by acoustic telemetry was conducted in the Bekanbeushi River system that flows through eastern Hokkaido in 2008–2010. A total of 39 tracked P. perryi showed extensive use of the river system, both upstream and downstream, regardless of the month or year. No tracked adult P. perryi stayed in the ocean for more than 1 day. Some of the fish (20%) dwelled in upstream habitat consistently from spring to autumn, while 40% of individuals showed wide utilisation of the entire upstream and downstream systems. Although 39.4% of tracked fish utilised two or more primary tributaries to the main river, 6.1% used only the main river system. Distinct variability was observed between individuals based on the proportion of time spent in each stream reach (up‐, mid‐, and downstream). A trend was observed in 2008 and 2010 showing that tracked fish moved to the upper stream reaches when water temperatures downstream increased. This trend was not observed in 2009 when the summer water temperature downstream was more than 2 °C below average when compared to 2008 and 2010. Our results suggest that adult P. perryi in the Bekanbeushi River system exhibit high behavioural plasticity, that is, the fish can select habitats based on their own individual requirements. Our results also demonstrate the importance of physical continuity among river reaches both upstream and downstream such that P. perryi does not experience barriers in moving to optimal habitats.     

Cloning and characterization of the antigenic membrane protein (Amp) gene and in situ detection of Amp from malformed flowers infected with Japanese hydrangea phyllody phytoplasma

A Japanese hydrangea phyllody (JHP) disease found throughout Japan causes economic damage to the horticultural industry. JHP phytoplasma-infected Japanese hydrangea plants show several disease symptoms involved in floral malformations, such as virescence, phyllody and proliferation. Here, we cloned and characterized the antigenic membrane protein (Amp) gene homolog from the JHP phytoplasma (JHP-amp), expressed the JHP-Amp protein in Escherichia coli cells, and then obtained an antibody against JHP-Amp. The antibody against JHP-Amp had no cross-reactions with the antibody against the Amp protein from a closely related onion yellows phytoplasma. This serologic specificity is probably due to the high diversity of the hydrophilic domains in the Amp proteins. The in situ detection of the JHP-Amp protein revealed that the JHP phytoplasma was localized to the phloem tissues in the malformed flower. This study shows that the JHP-Amp protein is indeed a membrane protein, which is expressed at detectable level in the JHP phytoplasma-infected hydrangea.     

First report of rust disease on ohia and the causal fungus, <Emphasis Type="Italic">Puccinia psidii</Emphasis>, in Japan

In 2007, a rust disease of ohia (Metrosideros polymorpha) was found in Japan. We identified this pathogen as Puccinia psidii based on its morphological characters and the internal transcribed spacer (ITS) sequence of the ribosomal DNA. This pathogen was pathogenic on Eucalyptus amplifolia and E. rudis in addition to previously reported host species. This is the first report in Japan of a rust disease on ohia and the occurrence of its causal fungus, P. psidii.     

First report of phytophthora rot on <Emphasis Type="Italic">Wasabia japonica</Emphasis> caused by <Emphasis Type="Italic">Phytophthora drechsleri</Emphasis> in Japan

In September 2014, Phytophthora rot on wasabi plants [Wasabia japonica (Miq.) Matsum.] was found for the first time in the city of Okutama, Tokyo, Japan. A Phytophthora sp. strain was constantly isolated from brown stem bases and rhizomes of infected plants. The same symptoms as those observed in the field were produced in vitro through inoculation of test plants with the isolated Phytophthora sp. The fungus was identified as Phytophthora drechsleri based on morphological and DNA sequence comparison. Phytophthora rot, “eki-byo” in Japanese, is proposed for this disease common name.     

First report of powdery mildew on zinnia, blue torenia, dahurian patrinia and scoparia caused by genus Euoidium in Japan

Zinnia, blue torenia, dahurian patrinia, and scoparia were found to be affected by powdery mildews from 2006 to 2008 in Tokyo. Abundant white, powdery colonies were observed to grow on the stems and leaves of each plant species resulting in chlorosis and eventual dieback of infected leaves and stems. Based on the morphological characteristics of the strain from each plant species, the causal agents were determined to belong to the genus Euoidium and pathogenicity to each original host was confirmed through inoculation experiments. This is the first report of Euoidium infection on these four plant species in Japan.     

Plant viruses and viroids in Japan

Journal of General Plant Pathology - An increasing number of plant viruses and viroids have been reported from all over the world due largely to metavirogenomics approaches with technological...     

Molecular evidence that a lily-infecting strain of Tulip breaking virus from Japan is a strain of Lily mottle virus

The sequence of the 3-terminal 2074 nucleotides (nts), excluding the 3-poly (A) tail, of RNA of a potyvirus isolated from lily (Lilium Asiatic hybrid cv. Enchantment) in Japan, currently tentatively designated as Tulip breaking virus-li (TBV-li), was determined. The sequence started within a single open reading frame (ORF) that encoded the carboxyl terminus of the large nuclear inclusion protein (NIb) and the complete 275-amino-acid coat protein (CP), followed by a 3-untranslated region (3-UTR) of 204 nts. The CP of TBV-li shared 91% amino acid (aa) sequence identity with that of TBV lily strain Dutch isolate (TBV-lily). The nt sequences of their 3-UTR were 94% identical. However both viruses shared only 60–65% sequence identities with TBV tulip strain Niigata isolate in the corresponding regions. The results suggest that TBV-li is closely related to TBV-lily, and that these two TBV lily strains should be classified into a species different from TBV tulip strains. We therefore support a proposal to rename TBV-lily Lily mottle virus (LMoV), and suggest that TBV-li is another strain of LMoV (LMoV-J).     

First report of Choanephora rot of ice plant (<Emphasis Type="Italic">Mesembryanthemum crystallinum</Emphasis>) caused by <Emphasis Type="Italic">Choanephora cucurbitarum</Emphasis> in Japan

In summer 2007, leaf and stem rot of ice plants was found in a hydroponic greenhouse in Japan. The causal agent was a fungus identified as Choanephora cucurbitarum (Berkeley & Ravenel) Thaxter, based on pathogenicity, morphology, mating tests, and sequence analysis of the ribosomal DNA ITS region.