Effects of cesium (Cs) on plant growth and accumulation of radioactive Cs by higher plants are surveyed as the first step of phytoremediation for radionuclide removal from contaminated soil and water environments. Cs is taken up dominantly from roots and translocated to shoot as an analog for potassium (K). Cs is a strong inhibitor of plant growth at the concentration of more than 10μM and an antagonistic agent to K. There are interspecific differences in radioactive Cs accumulation and several Chenopodiaceae species such as qinoa and beet accumulate higher radioactive cesium in shoots. These results indicate that radioactive Cs can be removed by plants from contaminated soil, but it is important how plant materials which were absorbed radioactive Cs are processed. The facts that external K application reduces Cs toxicity and uptake suggest the avoidance of Cs contamination in crops by excess K nutrition.

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The production of metal-containing grains through the leaf trichomes is observed when tobacco (Nicotiana tabacum L.) plants were exposed to toxic levels of cadmium (Cd) or zinc (Zn). Synchrotron-radiation based X-ray microanalyses were used to elucidate the mineral phases. Micro X-ray diffraction (μ-XRD) revealed that the large majority of the grains were composed essentially of Cd or Zn-substituted calcite (calcium carbonate). The presence of metal-substituted calcite was confirmed by micro-extended X-ray absorption fine structure (μ-EXAFS) spectroscopy. cDNA libraries were constructed from control and Cd-treated leaf trichomes. Almost 2,000 expressed sequence tag cDNA clones were sequenced to analyze gene expression in control and Cd-treated leaf trichomes. Confocal laser scanning microscopy (CLSM) showed that glutathione levels in tip cells of both long and short trichomes were higher than those in other types of leaf cells, indicating the presence of an active sulfur-dependent protective system in trichomes. Some cysteine-rich pathogenesis-related proteins harboring secretion signals in N-terminal were expressed specifically or dominantly in trichomes and are possible candidates for the sequestration of metals. Our results show the formation of metal-containing biogenic calcite through the trichomes is a novel mechanism involved in metal detoxification. The trichome-specific transcriptome approach was revealed to be a powerful tool to investigate the defensive functions of trichomes against both abiotic and biotic stress, and a better understanding of the biochemical and genetic regulations of biomineralization.

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We tried to produce new varieties of sweet potato, Ipomoea batatas (L.) Lam. which are superior in taste and rich in functional pigments. This was carried out through cell fusion between sweet potato cultivars, Ariakeimo, Purple sweet lord and Benihayato. First, the density of protoplasts at the fusion stage and the composition of initial culture medium were investigated. As a result, through the fusion between Ariakeimo and Purple sweet lord at a density of 1.0×10⁵ protoplasts/ml in dark at 25℃, the visible micro-callus of about 2〜3 mm in diameter, was formed on N6 medium supplemented with 0.1 mg/l 2,4-dichlorophenoxyacetic acid, 0.5 mg/l kinetin, 0.2 M sucrose and 0.6 M mannitol, pH5.8. Second, the composition of efficient regeneration medium was investigated in the plant regeneration from petiole callus of Ariakeimo, Purple sweet lord and Benihayato. Eventually it became obvious that individual shoot induced from the callus have grown into young plant at a high rate on the MS medium supplemented with 0.03 mg/l α-naphthaleneacetic acid, 0.01〜0.09 mg/l 6-benzyladenine, 0.087 M sucrose and 1.2% agar.

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The standard rice cultivars for ripening capability under high temperature conditions (RCHTC) were selected in Shiga Prefecture. Twenty five rice cultivars were cultured in green house on a paddy field to evaluate the RCHTC. Among extremely early cultivars and early cultivars, the varietal differences in the percentage of whole grain and white immature grain influenced with husked rice quality were observed. The order of cultivars in RCHTC was fairly consistent between 2009 and 2011. Therefore, we selected following cultivars as standard: 'Fusaotome' for "strong", 'Tentakaku', 'Hanaechizen' and 'Kosijiwase' for "moderate strong" (for extreme early cultivar), 'Etsunan222', 'Koshiibuki' and 'Lake65' for "moderate strong" (for early cultivar). Among medium and late cultivars, the order of cultivars in RCHTC differed annually. Therefore, it was thought that further study was needed to select standard for medium and late cultivar, including testing new cultivars.

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An efficient gene transformation is a crucial for complementation test to identify the agronomically important genes. However, significant varietal difference was observed in the efficiency of Agrobacterium-mediated transformation in rice. Gimbozu has become a valuable research material for its highly activated transposable element, mPing. With the use of mPing SCAR markers and mPing tagging system, we have successfully identified several mutant genes induced in Gimbozu. However, the very low transformation efficiency in Gimbozu prevents the complementation test and functional analysis of the candidate genes. Here, we report an effective Agrobacterium-mediated transformation method applicable to Gimbozu. It was very difficult to recover viable calli from Gimbozu after the co-cultivation with Agrobacterium to obtain the transformants, as it is very sensitive to the Agrobacterium infection. To overcome this difficulty, we used a very low density of Agrobacterium (OD600=0.001) for infection and a high amount of meropenem at first screening. It was also important to keep infected calli dry by blotting a callus on paper towel and air drying very carefully at the time of co-cultivation. As a result, we got a sufficient number of transgenic plants in a time (90 plants from 5 resistant calli). Transformation efficiency became 14.3% and the regeneration efficiency was more than 90%.

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Nonfunctional Rurm1 (Rice ubiquitin-related modifier-1) mutant line IM294 shows various aberrant phenotypes, such as a slender glume, a delay in heading date, an increase in the sterility rate, and a decrease in the germination rate. Like other ubiquitin-like proteins, the RURM1 protein is considered to be involved in these phenotypes by regulating the activity or function of target proteins. However, protein-modification function of RURM1 is not well understood. In order to elucidate the molecular function of the RURM1 protein, we aimed to identify the target proteins for RURM1 using transgenic rice overexpressing the Rurm1 gene. We obtained ten transgenic rice plants overexpressing the Rurm1 gene from 253 calli derived from the matured seeds of Nipponbare. When we performed western blot analysis against the RURM1 protein using crude protein extracted from transgenic rice plants, we detected four bands of 110, 52, 39, and 24 kDa. This indicates that the RURM1 protein harbors protein-modification function in rice.

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Root growth in rice seedlings was measured using a bi-layered agar medium, the upper half of which was nitrate free and the lower half of which contained different concentrations of nitrate. When the primary root grew up to approximately 15 mm in length, each germinated seed was transferred to a glass tube containing the bi-layered medium and cultivated at 25℃ under continuous lighting. In the japonica rice cultivars, Nipponbare and Kinmaze, the relative growth rate (RGR) of primary roots was highest between the first and second days after transplanting and gradually decreased. Although nitrate concentration had no effect on RGR in either cultivars, the bi-layered medium presented in this experiment would be useful for detecting nitrate sensing in roots, as change in root growth and proliferation of secondary roots were easily detected.

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Few knowledge of growth and yield on soybean 'Tanbaguro' were obtained by analyzing the results of the observation in Sasayama, Hyogo. First, we examined a positive correlation between the number of pods or pod weight (total 12 indicators) and the indicators for annual growth of 2010, and found more significant positive correlation between the number of pods or the pod fresh weight and the root fresh weight. Further, there existed a significant positive correlation between the root fresh weight and the aerial part fresh weight (at the 1% level), between the aerial part fresh weight and the total number of pods (at the 5% level) and between the aerial part fresh weight and the total pod fresh weight (at the 5% level). This positive correlation was also observed in the nine-year average data (2002-2010) as well as the data at 2010. Also, in the same conditions, with the growth of roots, the aerial part weight and the total number of pods increased. Then we surveyed the relationship between the annual soil moisture of 2010 and the growth and yield using simple soil moisture meter, as a result, the proper water level in summer soil moisture becomes many pod wearing and high-yield, the low water level in summer soil moisture becomes little pod wearing and low-yield. However, there are proper water level in case of low yields, that was brought about by multiple pests caused by inadequate pest control, growth defects and associated working poor tillage of furrow in the growing season. Therefore, increasing the amount of roots, preservation of the proper water level in summer soil moisture and enforcement of basic field management were considered to be the point of increasing the yield of soybean 'Tanbaguro'.

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Accurate and complete phenotypic data are essential to fields in crop science, plant breeding, and genetic researches. Often phenotyping and management becomes complicated due to large population sizes and the measurements of multiple traits. The vast amount of data require much time and labor, simultaneously leading to human errors. Technology can be exploited to improve the phenotypic data collection process through better tools or information management systems. "FieldBook" is a system we have developed to collect phenotypic data quickly and accurately in maize and rice, with a little manual data entry using data capture tools.

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In the process of disease protection, we encounter numerous problems such as breakdown of disease resistance cultivar and emergence of fungicide tolerant pathogen. For the success of durable disease protection, we have to study the infection strategies and lifecycles of pathogen, and prepare multiple disease protection measures. Most of the disease resistance (R) genes function as a receptor for pathogen. However, most of the R genes sense dispensable factor for life or pathogenicity. Once the dispensable factors mutate, the disease resistance cultivars carrying R genes fail to sense pathogen, causing the breakdown of disease resistance. If an R gene senses essential factor for life or pathogenicity, that is Achilles' heel of the pathogen, it would be a durable R gene. I present a possibility to create novel R gene by directed evolution.

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[in Japanese]

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Yamato-mana (Brassica rapa L. Oleifera Group), a traditional vegetable of Yamato, has some weak points: its growth is not uniform, and its outer leaves are liable to turn yellow after harvest. To overcome these disadvantages, we bred F₁ cultivars by use of the S haplotype, which controls self-incompatibility. By three-way crossing, we succeeded in the breeding of 'Natsunarana', which is suited for cultivation during the high-temperature season, and 'Fuyunarana', which is suited for the cultivation in the low-temperature season. Both cultivars were characterized by their uniform plant shapes; moreover, they were somewhat effective in preventing the yellowing of leaves than conventional cultivars. The period required for breeding of F₁ cultivars by three-way crossing was reduced by use of the S haplotype from the beginning of breeding.

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To resolve food problems and energy problems, it is necessary to improve the genetic potential of crops at a faster rate. Called genomic selection (GS), the selection method is getting a lot of attention as a technology accelerating breeding. In GS, the potential of plants is predicted based on whole-genome marker genotypes, and selection is performed on the predicted potential. GS has advantages over conventional marker assisted selection: (1) GS does not require QTL analysis for determining markers used for selection (2) GS has the potential to improve quantitative traits controlled by many polygenic QTL. Because GS uses a large number of DNA markers that are distributed throughout the entire genome, the use of a high-throughput genotyping technology is absolutely necessary. Here, I present an overview of GS and its related technologies.

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