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Sakai H.,Japan National Agriculture and Food Research Organization | Takeda A.,Chiba Prefectural Agriculture and Forestry Research Center | Mizukubo T.,Japan National Agriculture and Food Research Organization
ZooKeys | Year: 2011

Mixed populations of Xiphinema americanum-group species were detected from a root zone soil sample of Japanese holly, Ilex crenata, during a survey for plant-parasitic nematodes of commercial ornamental plant nurseries in Chiba Prefecture, Japan. From the result of the morphological study, the species were identifed as X. brevicolle and Xiphinema sp. Tis is the frst record of X. brevicolle in Japan. Morphometrics of X. brevicolle generally agree with those of the type specimens and the topotype specimens. Xiphinema sp. morphometrically resembles X. paramonovi except for tail length. Te mitochondrial COI region, the nuclear 18S rDNA and the nuclear large subunit rDNA D2/D3 region of the species were sequenced and compared in the molecular study. For the COI region, PCR primers were newly designed to obtain longer sequences, ca. 900 bp, than previously used. Sequence identities of COI, 18S and D2/D3 regions between these two populations were 84.0-84.1%, 99.9% and 98.1-98.2%, respectively. Phylogenetic analyses of maximum likelihood trees were carried out to compare genetic relationships among the group and some suggestions were made on the X. brevicolle-subgroup. © Hiromichi Sakai et al.


Takahashi M.,Tokyo University of Agriculture and Technology | Takahashi M.,Chiba Prefectural Agriculture and Forestry Research Center | Nakai M.,Tokyo University of Agriculture and Technology | Saito Y.,Tokyo University of Agriculture and Technology | And 3 more authors.
Viruses | Year: 2015

The smaller tea tortrix, Adoxophyes honmai (Lepidoptera: Tortricidae), is an economically important pest of tea in Japan. Previous work showed that a fast-killing nucleopolyhedrovirus (NPV) isolated from A. orana (AdorNPV) and a slow-killing NPV isolated from A. honmai (AdhoNPV) are both infectious to A. honmai larvae. Field application of these different NPVs was conducted against an A. honmai larval population in tea plants, and the control efficacy and transmission rate of the two NPVs were compared. The slow-killing AdhoNPV showed lower field efficacy, in terms of preventing damage caused by A. honmai larvae against the tea plants, than the fast-killing AdorNPV. However, AdhoNPV had a significantly higher horizontal transmission rate than AdorNPV. These results show that AdorNPV is suitable as an inundative agent, while AdhoNPV is an appropriate inoculative agent. © 2015 by the authors; licensee MDPI, Basel, Switzerland.


Kakui H.,Chiba University | Kakui H.,Nagoya University | Kato M.,Chiba University | Ushijima K.,Okayama University | And 3 more authors.
Plant Journal | Year: 2011

The S-RNase-based gametophytic self-incompatibility (SI) of Rosaceae, Solanaceae, and Plantaginaceae is controlled by at least two tightly linked genes located at the complex S locus; the highly polymorphic S-RNase for pistil specificity and the F-box gene (SFB/SLF) for pollen. Self-incompatibility in Prunus (Rosaceae) is considered to represent a 'self recognition by a single factor' system, because loss-of-function of SFB is associated with self-compatibility, and allelic divergence of SFB is high and comparable to that of S-RNase. In contrast, Petunia (Solanaceae) exhibits 'non-self recognition by multiple factors'. However, the distribution of 'self recognition' and 'non-self recognition' SI systems in different taxa is not clear. In addition, in 'non-self recognition' systems, a loss-of-function phenotype of pollen S is unknown. Here we analyze the divergence of SFBB genes, the multiple pollen S candidates, of a rosaceous plant Japanese pear (Pyrus pyrifolia) and show that intrahaplotypic divergence is high and comparable to the allelic diversity of S-RNase while interhaplotypic divergence is very low. Next, we analyzed loss-of-function of the SFBB1 type gene. Genetic analysis showed that pollen with the mutant haplotype S 4sm lacking SFBB1-S 4 is rejected by pistils with an otherwise compatible S 1 while it is accepted by other non-self pistils. We found that the S 5 haplotype encodes a truncated SFBB1 protein, even though S 5 pollen is accepted normally by pistils with S 1 and other non-self haplotypes. These findings suggest that Japanese pear has a 'non-self recognition by multiple factors' SI system, although it is a species of Rosaceae to which Prunus also belongs. © 2011 Blackwell Publishing Ltd.


Oida H.,Chiba Prefectural Agriculture and Forestry Research Center | Oida H.,Chiba University | Kadono F.,Chiba Prefectural Agriculture and Forestry Research Center | Kadono F.,Hosei University
Japanese Journal of Applied Entomology and Zoology | Year: 2011

We investigated the number of prey consumed in 24 h by 3rd and 5th instars of 2 species of polyphagous predators, Geocoris varius and G. proteus, provided with 4 prey species: Tetranychus urticae adult females, Frankliniella occidentalis 2nd instar, Aphis gossypii apterous adults, and Helicoverpa armigera eggs or 1st instar. The number of prey consumed differed significantly among prey densities in all predator×prey combinations, except in 3rd instar of G. varius provided with T. urticae or A. gossypii. Geocoris varius consumed prey maximally at higher prey density than G. proteus in 3rd instar with F. occidentalis larvae or H. armigera eggs, and in 5th instar, except with F. occidentalis larvae. Maximum numbers of prey consumed differed significantly between predator instars. Geocoris varius consumed more prey than G. proteus at 5th instar for all prey species. They also consumed more F. occidentalis larvae and H. armigera eggs than G. proteus at 3rd instar. These results show the higher predatory potential of G. varius and its promise as a biological control agent against major horticultural pests.


Oida H.,Chiba Prefectural Agriculture and Forestry Research Center | Oida H.,Chiba University | Kadono F.,Chiba Prefectural Agriculture and Forestry Research Center | Kadono F.,Hosei University
Applied Entomology and Zoology | Year: 2012

We studied the development of Geocoris varius (Uhler) and Geocoris proteus Distant reared on Ephestia kuehniella Zeller eggs at 20, 24, 26, 30, 33, or 36 °C. The lower developmental thresholds (T0) and the thermal constants (K) of eggs and nymphs of G. varius were 13.3 °C, 151.1 degree-days and 13.4 °C, 433.0 degree-days, respectively; those of G. proteus were 16.1 °C, 98.3 degree-days and 16.9 °C, 226.9 degree-days, respectively. The hatch rate of G. varius eggs was significantly lower at 33 °C than at ≤30 °C, and no eggs hatched at 36 °C. That of G. proteus was lowest at 20 °C and did not decline significantly at 36 °C. The survival rate throughout the nymphal period increased with temperature up to 30 °C in G. varius, and it was lowest at 20 °C in G. proteus. Thus, the optimal rearing temperatures for immature stages appear to be about 24-30 °C for G. varius and 26-33 °C for G. proteus. It might be possible to improve the efficiency of their mass production by controlling the rearing temperature in the above ranges. This would also make the developmental stages of nymphs more uniform and so prevent cannibalism in mass rearing. © 2012 The Japanese Society of Applied Entomology and Zoology.


Ishii H.,Japan National Institute for Agro - Environmental Sciences | Ishii H.,University of Tsukuba | Miyamoto T.,Horticultural Research Institute | Ushio S.,Chiba Prefectural Agriculture and Forestry Research Center | Kakishima M.,University of Tsukuba
Pest Management Science | Year: 2011

Background: Recently in Japan, isolates resistant to boscalid, a succinate dehydrogenase inhibitor (SDHI), have been detected in Corynespora cassiicola (Burk & Curt.) Wei and Podosphaera xanthii (Castaggne) Braun & Shishkoff, the pathogens causing Corynespora leaf spot and powdery mildew disease on cucumber, respectively. Resistant isolates of C. cassiicola are widely distributed and represent a serious problem in disease control at present. Novel SDHI fungicides, including fluopyram, are now under development. Results: The growth of very highly boscalid-resistant, highly resistant and sensitive isolates of C. cassiicola was strongly suppressed on fluopyram-amended YBA agar medium. Although boscalid and another SDHI, penthiopyrad, hardly controlled Corynespora leaf spot and powdery mildew on cucumber plants when very highly or highly boscalid-resistant isolates were employed for inoculation, fluopyram still exhibited excellent control efficacy against these resistant isolates as well as sensitive isolates of C. cassiicola and P. xanthii. Conclusion: Differential sensitivity to boscalid, penthiopyrad and fluopyram, clearly found in these two important pathogens of cucumber, may indicate involvement of a slightly distinct site of action for fluopyram from the two other SDHIs. This finding may lead to the discovery of unique SDHIs in the future. Copyright © 2011 Society of Chemical Industry.


Hisaka H.,Chiba Prefectural Agriculture and Forestry Research Center
Nippon Shokuhin Kagaku Kogaku Kaishi | Year: 2011

Retort pouch peanuts are a new product manufactured with the aim of increasing peanut production and consumption. Retort pouch peanuts are produced using raw pods and have a soft texture, similar to when boiled. This product is ready-to-eat and can be stored for long periods at room temperature. Cultivation controls and low temperature maintenance of raw pods, from harvest to retort treatment, are important for the manufacture of high quality products, both in appearance and taste. Retort pouch peanuts are a food produced by close co-operation of the grower and manufacturer, and since its introduction over 10 years ago, it has maintained a stable presence in the peanut-processing sector.


Suetsugu K.,Kyoto University | Fukushima S.,Chiba Prefectural Agriculture and Forestry Research Center
Plant Species Biology | Year: 2014

Pollination biology studies of the endangered orchid Cypripedium japonicum were conducted in its natural habitat using pollinator observation and hand-pollination experiments. The observed fruit set was as follows: artificial outcross-pollinated, 100%; artificial self-pollinated, 100%; pollinator-excluded, 0%; and emasculated flowers, 0%. These results show that this species, although self-compatible, is neither autogamous nor agamospermous. The fruit set for open-pollinated flowers was 14.9%, which suggests that the study population was subject to pollinator limitation. The nectarless flowers of C.japonicum were exclusively visited and pollinated by the queens of two bumblebee species (Bombus ardens and B.diversus diversus). It is probable that the nectarless flowers of C.japonicum attract pollinators through a generalized food deceptive system. © 2013 The Society for the Study of Species Biology.


Shirasawa K.,Kazusa DNA Research Institute | Hirakawa H.,Kazusa DNA Research Institute | Tabata S.,Kazusa DNA Research Institute | Hasegawa M.,Chiba Prefectural Agriculture and Forestry Research Center | And 6 more authors.
Theoretical and Applied Genetics | Year: 2012

Miniature inverted-repeat transposable elements (MITEs), some of which are known as active non-autonomous DNA transposons, are found in the genomes of plants and animals. In peanut (Arachis hypogaea), AhMITE1 has been identified in a gene for fatty-acid desaturase, and possessed excision activity. However, the AhMITE1 distribution and frequency of excision have not been determined for the peanut genome. In order to characterize AhMITE1s, their genomic diversity and transposition ability was investigated. Southern blot analysis indicated high AhMITE1 copy number in the genomes of A. hypogaea, A. magna and A. monticola, but not in A. duranensis. A total of 504 AhMITE1s were identified from the MITE-enriched genomic libraries of A. hypogaea. The representative AhMITE1s exhibited a mean length of 205. 5 bp and a GC content of 30. 1%, with AT-rich, 9 bp target site duplications and 25 bp terminal inverted repeats. PCR analyses were performed using primer pairs designed against both flanking sequences of each AhMITE1. These analyses detected polymorphisms at 169 out of 411 insertional loci in the four peanut lines. In subsequent analyses of 60 gamma-irradiated mutant lines, four AhMITE1 excisions showed footprint mutations at the 109 loci tested. This study characterizes AhMITE1s in peanut and discusses their use as DNA markers and mutagens for the genetics, genomics and breeding of peanut and its relatives. © 2012 The Author(s).


Suetsugu K.,Kyoto University | Fukushima S.,Chiba Prefectural Agriculture and Forestry Research Center
Plant Systematics and Evolution | Year: 2014

Calanthe discolor is a Japanese terrestrial orchid that is cultivated for its beautiful flowers arranged in racemose inflorescences. Although its propagation for horticultural purposes has been studied extensively resulting in the successful production of seedlings, little is known about the pollinators and breeding system of C. discolor in its natural habitat. The current study, which combined field observations and pollination experiments, was conducted to gain further insight into the reproduction of this important orchid species. Three bee species: Eucera nipponensis, Osmia cornifrons and Apis cerana japonica, were found to be effective pollinators, transferring the pollinaria on their heads. Pollination experiments also revealed that this species was self-compatible, although it was neither autogamous nor apogamous. The fruit set for the open-pollinated flowers was less than 10 %, suggesting a high degree of pollinator limitation, possibly as a result of the deceptive nature of this species. These results provide evidence that pollinator specificity is the primary mechanism of reproductive isolation between C. discolor and its close relative Calanthe striata, because the latter species is known to be exclusively pollinated by carpenter bee. © 2013 Springer-Verlag Wien.

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