Atsushi Ooshiro

Analysis of genetic and biological characters of japanese potato strains of ralstonia solanacearum

We assessed the geographic distribution, biovar, phylotype, DNA fingerprints (rep-PCR), and/or endoglucanase sequence of potato bacterial wilt pathogen, Ralstonia solanacearum (Rs), in Japan. Rs has been isolated from potato fields in southwestern, warm, temperate regions. Of the 188 isolates, 74 belonged to biovar N2 (39%), 44 to biovar 3 (24%), and 70 to biovar 4 (37%). Biovars N2 and 4 strains were widely distributed, from northern (Hokkaido) to southern (Okinawa) Japan. Based on the results of multiplex-PCR analysis, every potato strains belonged to either phylotype I or IV. Phylotype I comprised both biovars 3 and 4 strains. On the other hand, phylotype IV included biovar N2 strains. None of the strains belonged to phylotype II or III or biovar 1 or 2. Phylogenetic analysis based on DNA fingerprints and endoglucanase gene sequences clarified the genetic diversity of the Japanese potato strains and the close genetic relationship between the Japanese strains and the Asian strains in phylotypes I and IV.

Black band of Jew's marrow caused by Lasiodiplodia theobromae.

Stem rot and wilt of Jew’s marrow (nalta jute, Corchorus olitorius) were found on Is. Okinawa, Okinawa Prefecture, Japan, in March 2000. An anamorphic fungus, Lasiodiplodia theobromae was isolated repeatedly from the diseased plants and demonstrated to cause the disease. We coined the Japanese name “kurogare-byô” of Jew’s marrow for the present disease because it was new to Japan, although it had already been reported in India and Bangladesh as black band of the plant.

Bioassay-guided isolation of a novel chemoattractant for Ralstonia solanacearum in tomato root exudates

Tomato root exudates were analyzed using a bioassay to detect the chemoattractant for Ralstonia solanacearum. An activated charcoal-adsorbed fraction of root exudates from tomato cultivar Oogata-fukuju had chemoattractant activity for R. solanacearum strain MAFF 730138. The active component, purified using a Sep-Pak C18 cartridge, an activated charcoal column, diol-modified silica gel, and NH2-modified silica gel, is a new hydrophobic attractant. The final purified fraction produced a single peak in a diol-modified silica gel HPLC analysis.

First report of sclerotinia rot of mango caused by Sclerotinia sclerotiorum in Japan

A panicle blight with sclerotia was found on mango (Mangifera indica L.) in Okinawa Prefecture, Japan, in March 2016. Water-soaked lesions with white mycelia developed on panicles in the flowering stage; softening and decay of panicles was followed by formation of sclerotia. The fungus isolated from these sclerotia was identified as Sclerotinia sclerotiorum based on morphology and analysis of rDNA-ITS sequences. The isolate reproduced the symptoms on mango panicles in an inoculation test and was reisolated from flower stalks. This is the first report of sclerotinia rot (kinkaku-byo in Japanese) on mango caused by S. sclerotiorum in Japan.

Ethyl β-d-glucoside: a novel chemoattractant of Ralstonia solanacearum isolated from tomato root exudates by a bioassay-guided fractionation

ABSTRACT A chemoattractant of Ralstonia solanacearum isolated from the activated charcoal-adsorbed fraction of tomato root exudates was identified as ethyl β-d-glucopyranoside by instrumental analyses and comparison with synthetic preparations. Ethyl β-D-glucopyranoside showed unambiguous activity at above 1 µmol/disc. Its stereoisomers and D-glucose were inactive. Graphical Abstract Structure of chemoattractant for Ralstonia solanacearum isolated from tomato root exudates with the guidance of bioassay was identified as ethyl β-D-glucopyranoside.

First report of flyspeck of mango caused by Stomiopeltis sp. in Japan

Flyspeck symptoms were found on mango (Mangifera indica L.) in Okinawa Prefecture, Japan in June 2014. Just before harvest, surfaces of fruits and green branches developed groups of tiny black dots within dark smudges. A fungus was isolated from the dots on both fruits and branches. The isolates were identified as Stomiopeltis sp. based on pathogenicity, morphology and molecular phylogenetic analyses with rDNA-ITS and LSU sequences. This is the first report of flyspeck (susuten-byo in Japanese) on mango caused by Stomiopeltis sp. in Japan.