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Oyamada K.,Tochigi Prefectural Agricultural Experiment Station | Oyamada K.,Tochigi Prefectural Sustainable Agriculture Extension Center
Japanese Journal of Applied Entomology and Zoology | Year: 2013

Two spotted spider mites, Tetranychus urticae Koch the most important pests of strawberry, have developed resistance to chemical pesticides. We investigated the effects of high carbon dioxide atmospheres on two-spotted spider mites and strawberry plants just before transplanting. Percent mortality of adult female mites, young eggs(24 h after laying), and old eggs(48-72h) exposed to 60% CO2 at different temperatures(25,30, and 35oC) was evaluated over time. Mortality of all spider mite stages increased with exposure duration at each temperature, and the time required to achieve 100% mortality decreased as temperature increased. Exposure to 60% CO2 at 30oC for 16 h was 100% lethal to every developmental stage tested. Furthermore, 24 h of 60% CO2 treatment did not induce external damage or adversely affect flowering of the primary flower clusters on strawberry plants. In a large-scale test of elevated-CO2 atmospheres, the two spotted spider mite population was greatly suppressed relative to untreated fields, and strawberry plants remained healthy. Thus, our findings suggested that CO2 treatment could be used to propagate spider-mite-free plants in strawberry nurseries and enhance strawberry integrated pest management systems.


Himi E.,Okayama University | Yamashita Y.,Okayama University | Haruyama N.,Tochigi Prefectural Agricultural Experiment Station | Haruyama N.,Tochigi Prefectural Sustainable Agriculture Extension Center | And 3 more authors.
Euphytica | Year: 2012

A number of anthocyanin- and proanthocyanidin-free mutants (ant mutants) in barley were induced and selected because of breeding interest to reduce proanthocyanidins, which could cause haze and degrade the quality of beer. Ant loci, known as anthocyanin or proanthocyanidin synthesis genes, are classified into Ant1 to Ant30 through allelism tests. However, only the Ant18 gene has been molecularly shown to encode dihydroflavonol 4-reductase (DFR), which is involved in both anthocyanin and proanthocyanidin synthesis. In this study, an R2R3 MYB gene of barley was isolated by PCR and named Hvmyb10 due to its similarity to Tamyb10 of wheat, which is a candidate for the R-1 gene grain color regulator. The predicted amino acid sequences of Hvmyb10 showed high similarity not only to Tamyb10 but also to TT2, the proanthocyanidin regulator of Arabidopsis. Non-synonymous nucleotide substitutions in the Hvmyb10 gene were found in all six ant28 mutants tested. Mapping showed that a polymorphism in Hvmyb10 perfectly cosegregated with the ant 28 phenotype on the distal region of the long arm of chromosome 3H. These results demonstrate that ant28 encodes Hvmyb10, the R2R3 MYB domain protein that regulates proanthocyanidin accumulation in developing grains. The reduced grain dormancy of ant28 mutants compared with those of the respective wild types indicates that Hvmyb10 is a key factor in grain dormancy in barley. © 2011 Springer Science+Business Media B.V.


Kato N.,Japan National Agriculture and Food Research Organization | Kihou N.,Japan National Institute for Agro - Environmental Sciences | Fujimura S.,Fukushima Agricultural Technology Center | Ikeba M.,Agricultural Research Institute | And 4 more authors.
Soil Science and Plant Nutrition | Year: 2015

Huge amounts of radionuclides, particularly radiocesium, were discharged from the Fukushima Daiichi Nuclear Power Plant (FDNPP), and widespread of contamination of the land, including paddy fields, was observed. Because rice is a staple food in Japan, contamination of paddy fields is a serious problem, and practical countermeasures to reduce radiocesium contamination of rice are urgently required. Potassium (K) fertilization was previously shown to be an effective countermeasure in fields contaminated by the Chernobyl accident, but researchers did not study the effects on rice (Oryza sativa L.). In the present study, we performed urgent field experiments to test the use of K fertilization, as well as other soil amendments, to reduce radiocesium contamination of rice. We found that K fertilization was an effective and practical countermeasure to reduce radiocesium uptake by rice from several soil types in Japanese paddy rice culture. Other treatments, including the application of expanded vermiculite or manure, were effective, and the effect appears to be explained by their K content. Based on these results, the recommended level of exchangeable soil potassium to lower the radiocesium content of rice to acceptable levels is about 200 mg K kg–1 soil before the usual fertilization. This K fertilizer application criterion was applied in a wide, low-contaminated area from the 2012 cropping season, and satisfactory results have been obtained generally. © 2014 Japanese Society of Soil Science and Plant Nutrition


Yamashita K.,Japan National Agriculture and Food Research Organization | Nakazawa Y.,Tochigi Prefectural Agricultural Experiment Station | Namai K.,Tochigi Prefectural Agricultural Experiment Station | Amagai M.,Tochigi Prefectural Agricultural Experiment Station | And 3 more authors.
Breeding Science | Year: 2012

To investigate the mode of inheritance of apomixis in Chinese chive, the degrees of diplospory and partheno- genesis were evaluated in F1 and BC1 progenies derived from crosses between amphimictic and apomictic diploids (2n = 16, 2x). The F1 population was generated by crossing three amphimictic diploids 94Mo13, 94Mo49 and 94Mo50 with an apomictic diploid KaD2 and comprised 110 diploids and 773 triploids. All the diploid F1 plants examined were completely or highly eusporous and completely syngamic. All the triploid F1 plants examined were highly diplosporous and highly parthenogenetic. KaD2 could not transmit its high level of apomixis via monoploid pollen grains. The BC1 population, generated by crossing 94Mo49 with apomictic triploids found in the F1 offspring, exhibited heteroploidy; it comprised haploid, diploid, triploid, tetraploid and various aneuploid individuals. In this generation, clear segregation was observed between diplospory and parthenogenesis. Analysis of the BC1 population suggests that diplospory and parthenogenesis are each controlled by single dominant genes, D and P, respectively. However, all the BC1 plants character- ized as parthenogenetic were diplosporous. The absence of phenotypically eusporous parthenogenetic plants can be explained by assuming that the presence of diplospory gene is a prerequisite for the parthenogenesis gene expression in Chinese chive.


Yagi M.,Japan National Agriculture and Food Research Organization | Shirasawa K.,Kazusa DNA Research Institute | Waki T.,Tochigi Prefectural Agricultural Experiment Station | Kume T.,Aichi Agricultural Research Center | And 3 more authors.
Plant Molecular Biology Reporter | Year: 2016

A high-density genetic map, an essential tool for comparative genomic studies and quantitative trait locus fine mapping, can also facilitate genome sequence assembly. The sequence-based marker technology known as restriction site-associated DNA (RAD) enables synchronous, single nucleotide polymorphism marker discovery, and genotyping using massively parallel sequencing. We constructed a high-density linkage map for carnation (Dianthus caryophyllus L.) based on simple sequence repeat (SSR) markers in combination with RAD markers developed by double-digest RAD sequencing (ddRAD-seq). A total of 2404 (285 SSR and 2119 RAD) markers could be assigned to 15 linkage groups spanning 971.5 cM, with an average marker interval of 0.4 cM. The total length of scaffolds with identified map positions was 95.6 Mb, which is equivalent to 15.4 % of the estimated genome size. The generated map is the first SSR and RAD marker-based high-density linkage map reported for carnation. The ddRAD-seq pipeline developed in this study should also help accelerate genetic and genomics analyses and molecular breeding of carnation and other non-model crops. © 2016 Springer Science+Business Media New York


Horita M.,Japan National Institute for Agro - Environmental Sciences | Tsuchiya K.,Kyushu University | Suga Y.,Nagasaki Pest Control Station | Yano K.,Kochi Agricultural Research Center | And 3 more authors.
Journal of General Plant Pathology | Year: 2014

Ralstonia solanacearum is the causal organism of bacterial wilt of more than 200 species representing 50 families of plants in tropical, subtropical, and warm temperate regions in the world. Traditionally classified into five races based on differences in host range, R. solanacearum has also been grouped into six biovars on the basis of biochemical properties. With recent developments in molecular biology, various DNA-based analyses have been introduced and used to confirm that this binary system does not completely represent the diversity within R. solanacearum strains. Therefore, a new hierarchical classification scheme has been suggested, which defines R. solanacearum as a species complex and reorganized the concept of the species as a monophyletic cluster according to a phylogenetic analysis based on genomic sequence data. Here we discuss the current bacterial wilt situation and genetic relationships based on the recent classification system of Japanese R. solanacearum strains as well as worldwide strains. We also review the genetic, biochemical, and pathological characteristics of R. solanacearum strains, in particular, those affecting potato and Zingiberaceae plants as distinctly important pathogens in relation to continuously problematic and recent emergent diseases in Japan. © 2014, The Phytopathological Society of Japan and Springer Japan.


Monden Y.,Okayama University | Fujii N.,National Institute of Genetics Research Organization of Information and Systems | Yamaguchi K.,Okayama University | Ikeo K.,National Institute of Genetics Research Organization of Information and Systems | And 5 more authors.
Genome | Year: 2014

Retrotransposons have been used frequently for the development of molecular markers by using their insertion polymorphisms among cultivars, because multiple copies of these elements are dispersed throughout the genome and inserted copies are inherited genetically. Although a large number of long terminal repeat (LTR) retrotransposon families exist in the higher eukaryotic genomes, the identification of families that show high insertion polymorphism has been challenging. Here, we performed an efficient screening of these retrotransposon families using an Illumina HiSeq2000 sequencing platform with comprehensive LTR library construction based on the primer binding site (PBS), which is located adjacent to the 5′ LTR and has a motif that is universal and conserved among LTR retrotransposon families. The paired-end sequencing library of the fragments containing a large number of LTR sequences and their insertion sites was sequenced for seven strawberry (Fragaria × ananassa Duchesne) cultivars and one diploid wild species (Fragaria vesca L.). Among them, we screened 24 families with a "unique" insertion site that appeared only in one cultivar and not in any others, assuming that this type of insertion should have occurred quite recently. Finally, we confirmed experimentally the selected LTR families showed high insertion polymorphisms among closely related cultivars. © 2014 Published by NRC Research Press.


Waki T.,Tochigi Prefectural Agricultural Experiment Station | Horita M.,Japan National Institute for Agro - Environmental Sciences | Kurose D.,Japan National Institute for Agro - Environmental Sciences | Mulya K.,Indonesian Center for Agricultural Biotechnology | Tsuchiya K.,Kyushu University
Japan Agricultural Research Quarterly | Year: 2013

Asia-Pacific region was assessed by examining their biochemical properties, discriminating the phylogeny by polymerase chain reaction (PCR), and analyzing the egl and mutS gene sequences. These data were compared with those of reference strains covering the known diversity within the R. solanacearum species complex. Fifty-two of the Zingiberaceae plant isolates belong to either biovar 3 or biovar 4. Multiplex PCR analyses indicated that these strains belong to phylotype I. Phylogenetic analyses revealed that the investigated strains could be further divided into five or more groups and three major groups, based on the egl and mutS gene sequences, respectively. These groups were closely correlated with the host species and/or geographical origin. Our findings suggest that R. solanacearum strains affecting Zingiberaceae plants have multiple origins from within the Asia-Pacific region, and may have been disseminated with seed rhizomes.


Kamewada K.,Tochigi Prefectural Agricultural Experiment Station | Nakayama M.,Tochigi Prefectural Agricultural Experiment Station
Soil Science and Plant Nutrition | Year: 2011

We developed a method for predicting the total cadmium (Cd) concentration [Cd T] in soil solution. Disregarding minor ion pairs, [Cd T] was approximated by [Cd T] = [Cd 2+] + [CdCl +]. We assumed that Cd 2+ activity (Cd 2+) is dominated by the adsorption-desorption equilibrium, expressed stoichiometrically as, From this, we derived the balance equation, We calculated (CdCl +) as the product of (Cd 2+), chloride activity (Cl -), and a production constant. Our proposed prediction model was, We conducted an experiment using six types of soil and manipulated the Cd content, pH, and chloride concentration [Cl -] to determine the effect on Cd concentration in the soil solution. The soil solution measurements produced rectilinear regression relationships between log(Cd 2+) and logQ Cd - 0.6pH with slopes of 1.0 in all soil types, which validated the proposed Cd adsorption-desorption stoichiometry; the y-intercept of the regression lines represented log(K Cd/C Cd) and depended on the soil type. Furthermore, we were able to predict log(K Cd/C Cd) as a function of cation exchange capacity (CEC), and the activity coefficient (f Cd) as a function of electrical conductivity (EC) alone. Substituting these functions into the proposed prediction model, we obtained [Cd T]=0.288Q Cd10 -0.6pHCEC -2.37{1+2.23EC 0.490+95.5[Cl -]}. The model provided a high goodness-of-fit (r 2=0.956) between the predicted and measured values over a concentration range of more than five-orders of magnitude. This prediction equation therefore appears to have wide applicability, suggesting that Cd concentration in soil solution can be reliably predicted from measurements of Cd content, pH, CEC, EC, and [Cl -]. © 2011 Japanese Society of Soil Science and Plant Nutrition.


Katoh H.,Utsunomiya University | Fukuda T.,Tochigi Prefectural Agricultural Experiment Station | Nishigawa H.,Utsunomiya University | Natsuaki T.,Utsunomiya University
Journal of General Plant Pathology | Year: 2016

We developed a loop-mediated isothermal amplification (LAMP) assay for detecting Colletotrichum gloeosporioides, which causes anthracnose, in strawberry plants. Primer sets targeted the region from the gene encoding 5.8S ribosomal RNA to internal transcribed spacer 2, which is highly conserved in 25 Colletotrichum species in GenBank. Our results indicated that the LAMP assay, which uses template DNA prepared using microwave irradiation, is a simple and sensitive tool for detecting C. gloeosporioides in infected strawberry plants. Further, our results showed that the LAMP assay could differentiate Colletotrichum species such as C. acutatum, C. aenigma, and C. siamense. © 2016, The Phytopathological Society of Japan and Springer Japan.

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