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Yagi M.,Japan National Agriculture and Food Research Organization | Kimura T.,National Center for Seeds and Seedlings | Yamamoto T.,Japan National Agriculture and Food Research Organization | Isobe S.,Kazusa DNA Research Institute | And 2 more authors.
Molecular Breeding | Year: 2012

Bacterial wilt (Burkholderia caryophylli (Burkholder) Yabuuchi et al.) is one of the most damaging diseases during carnation (Dianthus caryophyllus L.) cultivation in Japan. To find molecular markers for use in marker-assisted selection, we constructed a simple sequence repeat (SSR)-based genetic linkage map of carnation using an F 2 population of 90 plants derived from a cross between a highly resistant line (85-11) and a susceptible cultivar (Pretty Favvare). To develop a large number of SSR markers, we constructed four new SSR-enriched genomic libraries and conducted expressed sequence tag analysis. We mapped 178 SSR loci into 16 linkage groups. The map covered 843. 6 cM, with an average distance of 6. 5 cM between two loci. This is the first report of a genetic linkage map based mainly on SSR markers in the genus Dianthus. Quantitative trait locus (QTL) analysis identified one locus for resistance to bacterial wilt in linkage group (LG) B4. The locus explained 63. 0% of the phenotypic variance for resistance to bacterial wilt. The SSR markers CES1161 and CES2643 that were closest to the QTL were efficient markers for selecting lines with resistance derived from line 85-11. A positional comparison using SSR markers as anchor loci revealed that LG B4 corresponded to LG A6 in a previously constructed map. We found that the position of the resistance locus derived from line 85-11 was similar to that of the major resistance locus observed for a highly resistant wild species, Dianthus capitatus ssp. andrzejowskianus. © 2011 Springer Science+Business Media B.V.

Tsushima S.,Japan National Agriculture and Food Research Organization | Tsushima S.,Japan National Institute for Agro - Environmental Sciences | Murakami H.,Japan National Agriculture and Food Research Organization | Akimoto T.,Japan National Agriculture and Food Research Organization | And 6 more authors.
Japan Agricultural Research Quarterly | Year: 2010

A model was developed to evaluate long-term temporal changes in disease severity (DS) of the clubroot disease of Chinese cabbage in the field with various management strategies. The model consists of a dose-response curve (DRC) of resting spore (RS) density of Plasmodiophora brassicae and DS, and the rate of RS density change due to leafy daikon cropping as a decoy plant, plowing the clubbed roots in the soil after harvest, and natural reduction. The DRC was estimated by greenhouse experiments. Three DRCs were estimated by experiments carried out in 1995-1997. The DRC in 1996 predicted the highest DS at all RS densities and hence was considered to represent a conducive condition, and that in 1997 predicted the lowest DS and was considered to represent a suppressive condition, respectively. Field data for three years (1996-1998) fell into an area surrounded by both DRC. This result confirmed the validity of the DRCs. Also the model was validated by field experiments where leafy daikon was cultivated before planting Chinese cabbage. The usefulness of the model for longterm prediction of temporal changes of DS was discussed.

Nakayama T.,Japan National Agricultural Research Center | Maoka T.,Japan National Agricultural Research Center | Hataya T.,Hokkaido University | Shimizu M.,Hokkaido Prefectural Tokachi Agricultural Experiment Station | And 3 more authors.
American Journal of Potato Research | Year: 2010

Spraing (brown rings or arcs) of potato caused by Potato mop-top virus (PMTV) occurred in a field of Tokachi, Hokkaido, Japan in 2005. To monitor the expansion of spraing-affected areas, we developed a soil diagnostic method that consisted of a bioassay using tomato as bait plant to trap the vector of PMTV, Spongospora subterranea, the causal agent of powdery scab of potatoes, followed by reverse transcription-polymerase chain reaction-microplate hybridization (RT-PCR-MPH) to detect the virus from roots of bait plants. After incubation of tomato seedlings grown with their roots immersed in a soil suspension at 18°C for 9 days, total RNA extracted from bait roots was analyzed by RT-PCR-MPH using PMTV-specific primers and a digoxigenin (DIG)-labeled probe. Soil diagnosis using the present method in an infested area revealed 137 of 224 fields (61.2%) were infested by PMTV although tubers harvested from only one of these fields had spraing. © 2010 Potato Association of America.

Maoka T.,Japan National Agricultural Research Center | Nakayama T.,Japan National Agricultural Research Center | Taniguchi M.,National Center for Seeds and Seedlings | Kano Y.,NCSS | And 5 more authors.
Potato Research | Year: 2013

In Japan, 12 viruses have been identified as causal agents of virus diseases of potato: Alfalfa mosaic virus, Cucumber mosaic virus, Potato aucuba mosaic virus, Potato leafroll virus (PLRV), Potato mop-top virus (PMTV), Potato virus A (PVA), Potato virus M (PVM), Potato virus S (PVS), Potato virus X (PVX), Potato virus Y (PVY), Tomato ringspot virus (ToRSV), and Tomato spotted wilt virus (TSWV). In a preliminary survey for viruses using ELISA, we found numerous virus species in landrace potatoes but only a few, e.g., PVY, in commercial ware potato crops. We have now modified a reverse transcription-polymerase chain reaction-microplate hybridization technique, developed for PVY, PLRV, and PMTV, to assay for the 12 viruses referred to above simultaneously. In leaf samples from 35 landraces, PVM, PVS, PVY, PLRV, PVA, and PVX were detected in 94%, 91%, 80%, 77%, 57%, and 43% of the landraces, respectively. These results indicate that potato landraces can act as a reservoir for these viruses with some landraces being asymptomatic. It is thus important to inspect and test for these viruses in seed potato production. © 2013 EAPR.

Yamamoto S.-I.,Japan National Institute of Agrobiological Science | Fukui K.,Japan National Institute of Agrobiological Science | Rafique T.,Pakistan National Agricultural Research Center | Khan N.I.,NWFP Agricultural Research System | And 4 more authors.
Plant Genetic Resources: Characterisation and Utilisation | Year: 2012

Cryopreservation using an aluminium cryo-plate was successfully applied to in vitro-grown strawberry (Fragaria×ananassa Duch.) shoot tips. The shoots were cold-hardened at 5°C for 3 weeks with an 8-h photoperiod. The shoot tips (1.5-2.0mm×0.5-1.0mm) were dissected from the shoot and pre-cultured at 5°C for 2d on Murashige and Skoog medium containing 2M glycerol and 0.3M sucrose. The pre-cultured shoot tips were placed on the aluminium cryo-plate containing ten wells embedded in alginate gel. Osmoprotection was performed by immersing the cryo-plates in a loading solution (2M glycerol and 0.8M sucrose) for 30min at 25°C. Dehydration was performed by immersing the cryo-plates in plant vitrification solution 2 for 50min at 25°C. Then, the cryo-plate with shoot tips was transferred into an uncapped cryotube that was held on a cryo-cane and directly immersed into liquid nitrogen (LN). After storage in LN, shoot tips attached to the cryo-plate were directly immersed into 2ml of a 1M sucrose solution for regeneration. Using this procedure, the average regrowth level of vitrified shoot tips of 15 strawberry cultivars reached 81%. This new method has many advantages and will facilitate the cryostorage of strawberry germplasm. © Copyright 2011 NIAB.

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