Presentations -
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「米／稲」の栄養とその改良 Invited
齋藤彰宏
第80回 日本伝統食品研究会 2026.04 日本伝統食品研究会
Event date： 2026.04
Language：Japanese Presentation type：Oral presentation (invited, special)
Venue：学習院大学（東京） Country：Japan
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Efficient Quenching by Phosphorylated Lhcb1–Enriched PSI–PSII Megacomplexes Formed in Thylakoid Membranes of Iron-Deficient Barley International conference
Akihiro Saito, Suzuha Hirayama, Miku Arakaki, Kai Nakano, Makio Yokono, Yusuke Shikanai, Kyoko Higuchi
67th Annual Meeting of the Japanese Society of Plant Physiologists in Tokyo 2026.03 the Japanese Society of Plant Physiologists
Event date： 2026.03
Language：English Presentation type：Poster presentation
Venue：Meiji University, Surugadai Campus Country：Japan
Barley varieties commonly enhance nonphotochemical quenching (NPQ), a thermal dissipation mechanism, under Fe deficiency to protect against photodamage. In this process, phosphorylated Lhcb1 (pLhcb1) plays an essential role in NPQ induction. However, the mechanism underlying pLhcb1 function in Fe-deficiency-induced NPQ has remained unclear. We recently discovered novel pLhcb1–PSII–PSI megacomplexes that are constitutively formed in the stroma lamellae of Fe-deficient barley. In barley chlorina mutants lacking Lhcb1 and the ability to enhance Fe-deficiency-induced NPQ, these megacomplexes were almost absent, suggesting that pLhcb1-mediated NPQ is associated with these complexes. To elucidate the energy-transfer pathways within the megacomplexes, we performed fluorescence decay–associated spectra (FDAS) using a variety whose megacomplexes remain stable during isolation. FDAS revealed that the megacomplexes mediate rapid energy transfer from PSII to PSI via LHCII, mainly composed of Lhcb1, resulting in highly efficient thermal dissipation. We are currently isolating large quantities of the megacomplexes to clarify their protein composition and to prepare for structural analysis.
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Analyses of Cell Wall-Related and Disease-Responsive Gene Mutants in Low-Calcium-Induced Cell Death in Arabidopsis International conference
Yamada Koharu, Saito Akihiro, Higuchi Kyoko, Shikanai Yusuke
67th Annual Meeting of the Japanese Society of Plant Physiologists in Tokyo 2026.03 the Japanese Society of Plant Physiologists
Event date： 2026.03
Language：English Presentation type：Poster presentation
Venue：Meiji University, Surugadai Campus Country：Japan
Calcium (Ca) deficiency symptom is a serious problem in crop production because it leads to necrosis, such as blossom end rot of fruits and tip burn of leafy vegetables. Ca deficiency alters cell wall composition and triggers defense responses, including cell death. Although much is known about pathogen-induced cell death, little is known about how Ca deficiency triggers necrosis or whether cell wall changes are involved.
In this study, we investigated the involvement of cell wall-related and disease-responsive genes in low Ca tolerance and the development of cell death in Arabidopsis. To date, we have measured the shoot fresh weights under low Ca conditions in 14 mutants defective in genes related to cell death and cell wall regulation. As a result, Ca channel deletion mutants (cngc2 and cngc4) and lignin-deficient mutants (myb15) showed a tendency of growth improvement compared with the wild-type plants under low Ca conditions, suggesting the possible involvement of Ca channels and lignin in low-Ca sensitivity. We are now going to clarify whether the mutants are involved in the occurrence of cell death in new leaves using trypan blue staining. -
Distribution of Iron Among Protein Complexes in Thylakoid Membrane of the Barley Cultivar ‘Sarab-1’ and Redistribution of Iron Under Iron-Deficient Conditions International conference
Kai Nakano, Akihiro Saito, Yusuke Shikanai, Kyoko Higuchi
67th Annual Meeting of the Japanese Society of Plant Physiologists in Tokyo 2026.03 the Japanese Society of Plant Physiologists
Event date： 2026.03
Language：English Presentation type：Poster presentation
Venue：Meiji University, Surugadai Campus Country：Japan
The Fe-deficiency-tolerant barley cultivar ‘Sarab-1’ accumulates more Fe in its thylakoids than other cultivars, despite having relatively lower amounts of Fe-rich photosystem I, suggesting the presence of additional Fe-containing molecules in ‘Sarab-1’. To explore these possible Fe-containing molecules in ‘Sarab-1’ thylakoid membranes, we are currently undertaking two complementary approaches: (1) sucrose density gradient ultracentrifugation followed by graphite furnace AAS, and (2) large-pore Clear Native (lpCN)-PAGE followed by LA-ICP-MS for Fe quantification from gels. The first method enables simultaneous detection of Fe-rich thylakoid fractions and proteome analysis. In contrast, lpCN-PAGE coupled with LA-ICP-MS may enable high-resolution analysis of Fe distribution. To integrate isotopic Fe labeling with these methods to quantify trace Fe distribution, we also conducted a ⁵⁷Fe pulse–chase experiment. As a result, when ⁵⁷Fe-labeled plants were subjected to Fe deficiency, ⁵⁷Fe was redistributed from the latest expanded leaves to the newly developing leaves in ‘Sarab-1’. We are now planning to perform lpCN-PAGE and LA-ICP-MS using ⁵⁷Fe-labeled thylakoid proteins.
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Spatiotemporal Analysis of Calcium Transport Into Tomato Fruits Using Real-Time ⁴⁵Ca Monitoring International conference
Takuma Hirashima, Yusuke Shikanai, Yong-Gen Yin, Nobuo Suzui, Mitsutaka Yamaguchi, Yuto Nagao, Akihiro Saito, Naoki Kawachi, Kyoko Higuchi
67th Annual Meeting of the Japanese Society of Plant Physiologists in Tokyo 2026.03 the Japanese Society of Plant Physiologists
Event date： 2026.03
Language：English Presentation type：Poster presentation
Venue：Meiji University, Surugadai Campus Country：Japan
Calcium (Ca) deficiency symptoms, such as blossom-end rot, often occur in fruits due to weak transpiration. It has been generally believed that Ca is primarily transported through the xylem via transpiration flow, with limited redistribution through the phloem.
To elucidate the mechanism of Ca transport to tomato fruit, we performed real-time monitoring using radioactive Ca (⁴⁵Ca) and a compact positron multi-probe system. A ⁴⁵Ca solution was injected directly into the main stem either in the daytime or at night, and its radioactivity was monitored by detectors placed on the stem, pedicel, and petiole.
The arrival order of ⁴⁵Ca depended on distance from the injection site, without an apparent day–night difference. Time–Activity–Curve profiles were classified into two patterns: (1) decline after a peak, (2) continuous increase or stable. Pattern (1) was likely observed in the main stem close to the injection site, and pattern (2) in the distal or terminal parts, suggesting successful detection of the spatiotemporal movement of ⁴⁵Ca from the main stem to the distal parts. We will discuss the dynamics of ⁴⁵Ca together with the proportions of mobile and immobile ⁴⁵Ca in each plant part. -
Relationship Between High-pH Responsive NRT2 Expression in Root Tips and Root Elongation Maintenance in Barley Under High-pH Conditions International conference
Hosono Taiga, Shikanai Yusuke, Saito Akihiro, Higuchi Kyoko
67th Annual Meeting of the Japanese Society of Plant Physiologists in Tokyo 2026.03 the Japanese Society of Plant Physiologists
Event date： 2026.03
Language：English Presentation type：Poster presentation
Venue：Meiji University, Surugadai Campus Country：Japan
Plant root elongation and nutrient uptake commonly require a moderately acidic apoplastic environment; however, some plant species can maintain root elongation even under high-pH conditions. We previously reported that barley can maintain root elongation even under alkaline conditions, and that a group of uncharacterized high-affinity nitrate transporter genes (termed NRT2uc group) are induced by high pH in the root meristematic and elongation zones. However, this finding was based on only one barley cultivar, ‘Ehimehadaka 1’. In this study, we compared the cultivars ‘Ehimehadaka 1’ and ‘Igri’ or ‘Shirohadaka 1’ and ‘Barke’, which can/cannot maintain root elongation under high-pH conditions, respectively, to examine whether the ability to maintain root elongation under high-pH conditions is associated with the expression of the NRT2uc genes. In addition, we are investigating whether MADS-box genes which could regulate the expression of NRT2 genes are also induced by high pH.
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Analysis of Quantitative Trait Loci Associated With Photosynthetic Adaptation to Iron Deficiency in Barley International conference
Karin Irie, Soichiro Matsuoka, Takehiro Kobayashi, Mayuko Furuhata, Nobuhiro Tanaka, Yusuke Shikanai, Akihiro Saito, Kyoko Higuchi
67th Annual Meeting of the Japanese Society of Plant Physiologists in Tokyo 2026.03 the Japanese Society of Plant Physiologists
Event date： 2026.03
Language：English Presentation type：Poster presentation
Venue：Meiji University, Surugadai Campus Country：Japan
A barley variety, ‘Sarab-1’, exhibits excellent tolerance to iron deficiency, showing a smaller reduction in photosynthetic rate than other varieties despite possessing relatively low amounts of iron-rich photosystem I. To quantitatively evaluate this trait of maintaining photosynthesis with minimal iron, we previously established a robust method to determine photosynthetic iron-use efficiency (PIUE) by calculating the carbon assimilation rate per mole of iron. In this study, we performed QTL analysis using an F₂ population derived from a cross between ‘Sarab-1’ (high PIUE variety) and ‘Musashinomugi’ (low PIUE). As the F₂ population segregated widely into high- and low-PIUE phenotypes under iron deficiency, we conducted GRAS-Di genotyping on individuals representing these phenotypic extremes. From the initial 6,507 genome-wide markers, quality control filtering and linkage-map construction yielded 477 highly reliable markers, which were then used for QTL analysis. Interval mapping detected a significant peak and several moderate-effect QTLs. We are currently increasing the F₂ population size to improve mapping accuracy and resolution.
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Exploration of Relationship Between Blossom-End Rot and Fruit Ionome in Tomato Authors International conference
Yusuke Shikanai, Yuka Takata, Amiri Watanabe, Akihiro Saito, Kyoko Higuchi
67th Annual Meeting of the Japanese Society of Plant Physiologists in Tokyo 2026.03 the Japanese Society of Plant Physiologists
Event date： 2026.03
Language：English Presentation type：Poster presentation
Venue：Meiji University, Surugadai Campus Country：Japan
Blossom-end rot (BER) often occurs in tomato under high-EC cultivation for high brix due not only to local calcium (Ca) deficiency but also to ionic imbalances. To achieve stable high-quality production, it is important to identify BER-tolerant cultivars/genes and clarify physiological factors, including fruit ionome, underlying BER tolerance. However, few studies have compared BER severity in relation to fruit ionomes across many cultivars grown under high-EC conditions.
To explore BER-tolerant cultivars and genes, we cultivated ~20 cultivars under normal and BER-inductive conditions (high EC, low Ca, and added NaCl) and analyzed BER incidence, brix, fruit weight, and fruit ionome (green/red stage; basal/tip regions; by ion chromatography or ICP-AES). Cultivars ‘Reiyoh’ and ‘House Momotaro’ have previously been reported as highly and less susceptible to BER, respectively. In our results as well, Reiyoh and House Momotaro showed high and low BER incidence, respectively, confirming that our cultivation reflects cultivar differences in BER susceptibility. In this poster, we present the relationships between BER and each trait examined, along with preliminary GWAS results. -
鉄欠乏オオムギのチラコイド膜に形成される巨大複合体中のリン酸化Lhcb1の機能
〇齋藤彰宏、新垣未来、中野快、山田涼子、角木柊平、鹿内勇佑、横野牧生、樋口恭子
日本植物学会・第89回大会（福岡国際会議場） 2025.09
Event date： 2025.09
Language：Japanese Presentation type：Poster presentation
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マイクロトムにおける尻腐れ誘導条件の探索
鹿内勇佑、高井麻帆、山本菜月、齋藤彰宏、樋口恭子
日本土壌肥料学会（新潟大学・五十嵐キャンパス） 2025.09
Event date： 2025.09
Language：Japanese Presentation type：Poster presentation
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オオムギの鉄欠乏耐性品種間差と集光性クロロフィル結合タンパク質Lhcb1のチラコイド膜上の分布の関係
樋口恭子、矢野衣吹、鹿内勇佑、齋藤彰宏
日本土壌肥料学会（新潟大学・五十嵐キャンパス） 2025.09
Event date： 2025.09
Language：Japanese Presentation type：Poster presentation
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Ca-45トレーサーによる大玉トマト中のCa輸送の時空間解析
平島拓磨, 鹿内勇佑, 尹永根, 鈴井伸郎, 山口充孝, 長尾悠人, 齋藤彰宏, 河地有木, 樋口恭子
日本土壌肥料学会（新潟大学・五十嵐キャンパス） 2025.09
Event date： 2025.09
Language：Japanese Presentation type：Oral presentation (general)
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Spatiotemporal analysis of Ca transport dynamics in tomato using Ca-45 tracer and compact multiprobe system International conference
Yusuke Shikanai, Takuma Hirashima, Yong-Gen Yin, Nobuo Suzui, Mitsutaka Yamaguchi, Yuto Nagao, Akihiro Saito, Naoki Kawachi, Kyoko Higuchi
2025.09
Event date： 2025.09
Language：English Presentation type：Oral presentation (general)
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Analysis of thylakoid membrane proteins responsible for protection of photosystem I in barley cultivar “Sarab 1” with high Fe deficiency tolerance International conference
Akihiro Saito, Keisuke Kurita, Nobuo Suzui, Naoki Kawachi, Yusuke Shikanai, Kyoko Higuchi
20th International Plant Nutrition Colloquium (IPNC, Port, Portugal) 2025.07 International Plant Nutrition Colloquium
Event date： 2025.07
Language：English Presentation type：Poster presentation
Venue：Port, Portugal Country：Portugal
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Tracer experiments for estimation of contributions of phloem and xylem to influx of Ca into fruits in tomato International conference
Yusuke Shikanai, Takuma Hirashima, Yong-Gen Yin, Mitsutaka Yamaguchi, Yuto Nagao, Akihiro Saito, Naoki Kawachi, Kyoko Higuchi
20th International Plant Nutrition Colloquium (IPNC, Port, Portugal) 2025.07 International Plant Nutrition Colloquium
Event date： 2025.07
Language：English Presentation type：Poster presentation
Venue：Port, Portugal Country：Portugal
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オオムギ品種サラブ１と武蔵麦を用いた光化学系の鉄欠乏順応に関するQTL解析 International conference
入江夏鈴、松岡宗一郎、小林岳央、古幡万由子、鹿内勇佑、斎藤彰宏、樋口恭子
第66回日本植物生理学会年会（金沢） 2025.03
Event date： 2025.03
Language：English Presentation type：Poster presentation
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オオムギ集光性クロロフィル結合タンパク質HvLhcb1.12を導入した形質転換イネの、光化学系タンパク質組成の解析 International conference
今野彩音、上山舜平、鹿内勇佑、齋藤彰宏、樋口恭子
第66回日本植物生理学会年会（金沢） 2025.03
Event date： 2025.03
Language：English Presentation type：Poster presentation
Country：Japan
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土耕栽培でのマイクロトムにおける尻腐れ発生環境要因の検討 International conference
鹿内 勇佑，山本 菜月，齋藤 彰宏，樋口 恭子
第66回日本植物生理学会年会（金沢） 2025.03
Event date： 2025.03
Language：English Presentation type：Poster presentation
Country：Japan
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大玉トマトにおけるカルシウム時空間動態のストロンチウムを用いた推定 International conference
平島 拓磨・鹿内 勇佑・齋藤 彰宏・樋口 恭子
第66回日本植物生理学会年会（金沢） 2025.03
Event date： 2025.03
Language：English Presentation type：Poster presentation
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鉄欠乏耐性のイネ品種間差と耐性を左右する要因
樋口恭子、岡村美音、松岡宗一郎、鹿内勇佑、齋藤彰宏
2024年度日本土壌肥料学会関東支部大会（山梨県甲府市） 2024.11
Event date： 2024.11
Language：Japanese Presentation type：Poster presentation