Keisuke Tomioka

Fruit rot of sweet pepper caused by Stemphylium lycopersici in Japan

A severe rot of postharvest fruits of sweet pepper, a variety of Capsicum annuum, was found in Kagawa Prefecture in southwestern Japan in August 1999. A fungus, isolated repeatedly from the diseased fruits and identified as Stemphylium lycopersici, was demonstrated to be pathogenic to fruits of sweet pepper. The disease was new to Japan, and the fungus was added to the pathogens causing fruit rot of C. annuum.

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.

Dumontinia root rot of liver leaf caused by Dumontinia tuberosa

Foliar wilt as well as crown and root rot with sclerotia formation has affected potted liver leaf (Hepatica nobilis var. japonica f. magna) in Ojiya, Niigata Prefecture, Japan, since 2006. Apothecia developed from the sclerotia on soil surface of pots with the diseased plants in March. A fungus forming the apothecia was identified as Dumontinia tuberosa (Sclerotiniaceae) based on its morphology and demonstrated to cause the disease. We coined the name “Dumontinia root rot (Dumontinia-negusare-byo in Japanese) of liver leaf” for the new disease.

Anthracnose of Nemesia strumosa caused by Colletotrichum fuscum

Severe wilt with spots and/or leaf and stem blight were found on a scrophulariaceous flowering plant, Nemesia strumosa, grown in Kagawa Prefecture, Japan, in February 1999. Wilted plants had numerous lesions and died early. A mitosporic fungus isolated repeatedly from the diseased plants was identified as Colletotrichum fuscum and was demonstrated to cause the disease. N. strumosa is a new host for C. fuscum, which has been known to attack foxglove (Digitalis spp.). The present disease was named “anthracnose of N. strumosa” as a new disease.

Damping-off of soybean caused by Pythium myriotylum in Japan

Severe rotting and blight of seedlings of soybean, Glycine max (L.) Merr., were found in Hiroshima Prefecture in the southwest region of Japan in July 2009. A filamentous microorganism, isolated repeatedly from the diseased seedlings and identified as Pythium myriotylum, was demonstrated to be pathogenic to seedlings of soybean. The disease was new in Japan, and we propose to include this oomycete as one of the pathogens causing damping-off of soybean.

White rust of Ipomoea caused by Albugo ipomoeae-panduratae and A. ipomoeae-hardwickii and their host specificity

In some areas of Japan, yellow spots with white pustules on leaves, stems, petioles, peduncles and calyces were found on Ipomoea nil, I. triloba, I. lacunosa and I. hederacea var. integriuscula. We demonstrated that the diseases on I. nil, I. triloba and I. lacunosa were caused by host-specific strains of Albugo ipomoeae-panduratae and defined three forma speciales of the fungus, respectively, for the three Ipomoea species: “f. sp. nile”, “f. sp. trilobae” and “f. sp. lacunosae”. Because the diseases were new to Japan, we coined the Japanese name “shirosabi-byo”, which means white rust. We also showed that the disease on I. hederacea var. integriuscula was caused by A. ipomoeae-hardwickii. We named this new disease “white rust (shirosabi-byo in Japanese)”.

Anthracnose of snapdragon caused by Colletotrichum destructivum

Severe spotting and blight of leaves caused by Colletotrichum destructivum were found on snapdragon (Antirrhinum majus L.), a scrophulariaceous ornamental, in open fields in Shizuoka Prefecture, Japan, from June through September 2004. The fungus is added to the group of the pathogens causing anthracnose of snapdragon.

Gray mold of pearl lupine caused by Botrytis cinerea

Severe blight of stems, leaves and pods caused by Botrytis cinerea was found on pearl lupine (Lupinus mutabilis), a legume crop, grown in Kagawa Prefecture, Japan, in March–June 1996–2002. This disease was named “gray mold of pearl lupine” as a new disease.

Restriction landmark genomic scanning (RLGS) in fungi

RLGS is a technique to detect DNA polymorphism using restriction sites as landmarks. It identifies the landmarks through direct end-labeling, two-dimensional electrophoresis and autoradiography, giving a profile with many spots to allow the scanning of numerous DNA loci. We successfully performed the technique on fungi using isolates ofColletotrichum acutatum andC. gloeosporioides in anamorphic Ascomycotina,Rhizopus oryzae in Zygomycotina,Phytophthora nicotianae in Mastigomycotina (or Oomycota) andRhizoctonia solani in anamorphic basidiomycotina. RLGS of total genomic DNA digested with three restriction enzymes,Not, I,EcoR V andMbo I, reproducibly gave specific profiles of ca. 400 to 1.600 spots for each isolate. A polymorphic spot appearing to reflect a genetic difference between the twoColletotrichum species was found in the profiles of the isolates. No other common spots were found in any combination of isolates of the twoColletotrichum species, and thus the other spots on the profiles were regarded as unique to each isolate. These results indicated that RLGS could be applied, as a powerful fingerprinting technique based on genetic information from the whole genomic DNA, to search for useful DNA markers for taxonomic and genomic studies on many fungal species.

Anthracnose of bacopa caused by Colletotrichum destructivum

Severe spotting and blighting of leaves were found on bacopa (Sutera cordata), a scrophulariaceous ornamental, in greenhouses in Gunma Prefecture, Japan, from January through February 2007. After we isolated and identified the causal fungus as Colletotrichum destructivum and inoculated host plants with the isolate to confirm pathogenicity, we named this new disease anthracnose of bacopa.