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Matsushita Y.,Japan National Agriculture and Food Research Organization | Shima Y.,Forestry and Fisheries Research Center
Phytoparasitica | Year: 2015

Replication and cellular movement of viroids are dependent on host plant components. Low temperatures reduce the physiological activity of host plants and thus suppress the levels of viroids. Chrysanthemum stunt viroid (CSVd) concentration was reduced in infected chrysanthemum (Chrysanthemum morifolium) plants subjected to low-temperature treatment compared with untreated plants. In this study, we investigated the distribution patterns of CSVd in the developing shoot tips of CSVd-infected chrysanthemum plants subjected to one-month, three-month, and six-month low-temperature treatment using in situ hybridization. After one month of low-temperature treatment, strong CSVd signals were detected in leaf primordia (LP) and the apical dome (AD); after three months, weak CSVd signals were detected in LP and the AD; while after six months, CSVd signals were not detected in LP or the AD, but only in tissues within the vascular bundle directly beneath viroid-free LP and AD areas. These changes in the distribution of CSVd in shoot tips subjected to low-temperature treatment might result from a reduction in viroid replication and/or the inhibition of viroid intra- and intercellular movement. © 2015, Springer Science+Business Media Dordrecht.

Ashizawa T.,Japan National Agricultural Research Center | Takahashi M.,Japan National Agricultural Research Center | Moriwaki J.,Forestry and Fisheries Research Center | Hirayae K.,Japan National Agricultural Research Center
Journal of General Plant Pathology | Year: 2011

False smut, caused by Ustilaginoidea virens, is a serious disease of rice worldwide. To evaluate false smut resistance in rice, we developed a method combining the cultivation of the main culm of rice plants in the greenhouse and rapid preparation of a conidial suspension to inject into the leaf sheath. The method was used to evaluate false smut resistance in 18 varieties/lines of rice. For comparison, field trials were also carried out in 2007 and 2008. The results indicated that the greenhouse method was more reproducible than field trials: commercial varieties tested were resistant; almost all the forage varieties were highly susceptible; and blast-resistant varieties/lines were mostly resistant to false smut. Thus, this inoculation method will be useful for determining the level of false smut resistance in rice and for breeding resistant varieties. © 2010 The Phytopathological Society of Japan and Springer.

Okuda S.,Kagoshima University | Okuda M.,Chiyoda Corporation | Matsuura S.,Hiroshima Prefectural Agriculture Research Center | Okazaki S.,Forestry and Fisheries Research Center | Iwai H.,Kagoshima University
European Journal of Plant Pathology | Year: 2013

The vector competence of Frankliniella occidentalis for Chrysanthemum stem necrosis virus (CSNV) was evaluated. Three vector strains with distinct competences for Tomato spotted wilt virus (TSWV) transmission were investigated, including an artificially selected strain (TsH) that has a particularly high competence (>90 %). Newly hatched larvae of F. occidentalis were given an acquisition access period of 5 days on CSNV-infected D. stramonium leaves, and reared to maturity. Their transmission efficiencies were examined using a leaf disk assay using Petunia x hybrida leaves. Following the leaf disk assay, the virus accumulation in the vectors was examined via a double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) of their bodies. The results showed that the CSNV acquisition and transmission efficiency of the TsH strain did not differ from those of the others, indicating that the competence of F. occidentalis as a vector for CSNV is not related to that for TSWV. The CSNV transmission and acquisition efficiencies of two F. intonsa strains (Hiroshima and Fukuoka) were also evaluated. In Hiroshima strain, 35 % of adults were viruliferous, but only two transmitters (3 %) were observed. In Fukuoka strain, 6 % were viruliferous, and no transmitters were observed. These results indicate that F. intonsa cannot be a major vector for CSNV. The accumulation of CSNV in the adults of F. occidentalis and F. intonsa evaluated using DAS-ELISA showed a significant difference in ELISA values among transmitter, viruliferous non-transmitter, and non-viruliferous individuals. These results clearly demonstrated that only transmitters that accumulated a threshold quantity of virus can transmit CSNV to plants. © 2013 KNPV.

Encarnacion A.B.,Tokyo University of Marine Science and Technology | Fagutao F.,Tokyo University of Marine Science and Technology | Shozen K.-I.,Forestry and Fisheries Research Center | Hirono I.,Tokyo University of Marine Science and Technology | Ohshima T.,Tokyo University of Marine Science and Technology
Food Chemistry | Year: 2011

We investigated the effects of decreasing phenoloxidase (PO) activity and prophenoloxidase (proPO) gene expression on the inhibition of postharvest melanosis formation in the red queen crab, Chionoecetes japonicus. The cDNA of proPO from hemocytes of C. japonicus was partially cloned and sequenced. Immersion of live crabs in a 1.0% ergothioneine (ESH)-rich mushroom extract (Flammulina velutipes; ME) solution resulted in significant inhibition of haemolymph PO activity and a reduction of the proPO gene expression in hemocytes that consequently controlled melanosis in the crabs during ice storage. Treatments with a 0.05% w/v sodium sulphite solution or a 0.05% w/v 4-hexyl-1,3-benzenediol solution had similar positive effects as the treatment with a 1.0% ME solution in vivo. In vitro experiments showed that authentic l-(+)-ESH inhibited PO activity and decreased proPO gene expression in crab hemocytes. Thus, the application of ESH-rich ME can be a novel alternative to synthetic melanosis-inhibiting agents to control postharvest melanosis in crabs. © 2011 Elsevier Ltd. All rights reserved.

Matsuzuka K.,Tohoku University | Kimura E.,Japan National Agricultural Research Center | Nakagawa K.,Tohoku University | Murata K.,Forestry and Fisheries Research Center | And 2 more authors.
Food Chemistry | Year: 2013

Rice tocotrienol (T3) has gained attention due to its physiological activities (e.g.; antiangiogenesis). However, the biosynthetic pathway for T3 production in rice grain has not been well studied. We hypothesized that T3 biosynthesis enzymes and/or precursors play an important role in T3 production in whole grain. This proposal was evaluated in rice (Oryza sativa L.) by PCR and HPLC techniques. Grain tocopherol as well as flag leaf vitamin E levels were also investigated for comparison. For rice samples 14 days after flowering, grain was abundant in T3, but not in flag leaf. Expression of a gene encoding homogentisate geranylgeranyltransferase (HGGT, which has long been believed to be important for T3 production) differed significantly between grain and flag leaf. We then investigated rice samples during the grain maturation period, and found that grain T3 and HGGT levels increased in the early stage and then reached a plateau. T3 precursors such as homogentisate and geranylgeranyl pyrophosphate decreased during maturation. No increase in grain T3 from the middle to late stages of maturation and a decrease in T3 precursors during maturation suggest that HGGT would be an essential, but not limiting factor for T3 biosynthesis, and T3 precursors could regulate the T3 level in grain. The results of this study would be useful for nutraceutical purposes (e.g.; development of T3-overproducing rice for the prevention of angiogenic disorders). © 2013 Elsevier Ltd. All rights reserved.

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