研究者詳細 - 仲田（狩野）　麻奈

論文 - 仲田（狩野）　麻奈

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Revealing the influences of organic amendment-derived dissolved organic matter on growth and nutrient accumulation in lettuce seedlings (<i>Lactuca sativa</i> L.) Open Access

Sonsri, K; Phankamolsil, N; Kano-Nakata, M; Watanabe, A

OPEN AGRICULTURE 9 巻 ( 1 ) 2024年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Open Agriculture

Although the application of organic amendment (OA) is a well-established agricultural practice, the effectiveness, optimal concentration, and key characteristics of OA-derived dissolved organic matter (DOM) in promoting the growth and nutrient accumulation of lettuce are not fully understood. To gain a better understanding, the effect of OA-derived DOM that was prepared from rapeseed oil cake (ROC) on the growth of lettuce was examined. Lettuce seedlings (7 days old) were transplanted into a hydroponic nutrient solution with varying DOM concentrations (10, 20, and 30 mg C L–1) along with the control treatment (no DOM addition), and shoot and root growth of lettuce was recorded and nutrient accumulation in lettuce was analyzed after 14 days. Compared to the control treatment, the soil and plant analyzer development value, shoot fresh weight, shoot dry weight, and leaf area were significantly greater (P < 0.05) in 20 mg C L–1 DOM concentration, while the maximum leaf width was significantly higher (P < 0.05) in 10 mg C L–1 DOM concentration. The root fresh weight, root dry weight, root length, root surface area, and number of lateral roots were significantly greater (P < 0.05) in 20 mg C L–1 DOM concentration than in the control treatment. DOM concentrations of 20 and/or 10 mg C L–1 also resulted in enhanced carbon, phosphorus, potassium, sulfur, silicon, and boron contents in lettuce. Overall, these findings suggest that ROC-derived DOM can promote growth and nutrient accumulation in lettuce seedlings, with 20 and/or 10 mg C L–1 being suitable concentrations.

DOI： 10.1515/opag-2022-0397

Rice Yield and Grain Quality under Fluctuating Soil Moisture Stress

Deshabandu, KHST; Noda, Y; Marcelo, VAC; Ehara, H; Inukai, Y; Kano-Nakata, M

AGRONOMY-BASEL 14 巻 ( 9 ) 2024年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Agronomy

In rainfed lowlands and water-saving cultivation systems, rice plants are often exposed to soil moisture fluctuation (SMF). Improving yield as well as grain quality is the main target for breeding under water-stressed environments. This study investigated the effects of different water treatment on yield, growth parameters, and grain quality under field conditions in Japan for 2 years. Two rice genotypes, Nipponbare (japonica) and G3-3 (derived from Nipponbare and KDML105, indica), were grown under continuous waterlogging (CWL) and SMF conditions. As the grain quality characteristics, grain appearance, dimension, and taste parameters were evaluated as well as yield and yield components. SMF reduced the yield, and G3-3 showed a higher yield than Nipponbare under SMF, which was attributed to the higher number of spikelets per panicle. G3-3 showed a better taste score (mark) with lower protein and amylose contents compared to Nipponbare. However, G3-3 had a higher percentage of broken grains, indicating a trade-off in grain quality traits. Non-structural carbohydrate dynamics may be involved as one of the grain quality characteristics. G3-3 demonstrated a superior yield under SMF conditions and have potential to show superior grain quality, indicating that the introgressed segments of G3-3 may be responsible for the grain quality traits associated with root plasticity.

DOI： 10.3390/agronomy14091926

Nitrogen-fixing bacterial community in sago palm roots in different soil environments of East Malaysia and South Thailand Open Access

SAGO PALM 32 巻 ( 1 ) 頁： 15 - 29 2024年9月

Dipping vigorous seedling roots in phosphorus-enriched slurry at transplanting efficiently increases lowland rice yields

Rakotoarisoa, NM; Tsujimoto, Y; Oo, AZ; Tashiro, T; Kano-Nakata, M; Ehara, H

CROP AND ENVIRONMENT 2 巻 ( 4 ) 頁： 202 - 208 2023年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Crop and Environment

P-dipping refers to the placement of phosphorus (P) fertilizer at the root system during transplanting of rice by adhering P-enriched slurry to the seedling roots. This approach is beneficial for smallholder farmers in sub-Saharan Africa who apply small amounts of P to highly P-fixing soils. This study aimed to identify the optimum seedling age for maximizing the impact of P-dipping. Pot experiments revealed that the adhered amounts of slurry to the roots with P-dipping increased in a sigmoidal pattern against seedling age. Correspondingly, the effect of P-dipping on the initial biomass was enlarged with older seedlings in a sigmoidal pattern, increasing slowly during the young seedling age (2.9–4.5 leaves), sharply during the intermediate seedling age (4.5–6.3 leaves), and plateauing during the old seedling age (6.3–7.0 leaves). Combining P-dipping with much older seedlings (> 7.0 leaves) resulted in severe transplanting shock and plant death. On-farm trials on 90 fields in Madagascar demonstrated a significant interaction between seedling age and P treatment on grain yield. The highest yield gains over the control from P-dipping were observed in seedlings with intermediate age (1.0 t ha−1), followed by old (0.7 t ha−1) and young (0.6 t ha−1) seedlings. These results suggested that vigorous and intermediate seedlings with higher slurry adherence than young seedlings and a lower risk of transplanting shock than old seedlings benefited most from P-dipping. This finding provides smallholder farmers with practical knowledge on how to apply the P-dipping more efficiently for achieving improved P management for sustainable rice production.

DOI： 10.1016/j.crope.2023.10.002

Specialty Rice (Oryza sativa L.) with High and Stable Grain Yield under Rainfed Lowland Conditions

Agustin, AML; Ordonio, JL; Natividad, MBS; Lucob-Agustin, NB; Suralta, RR; Ehara, H; Mitsuya, S; Kano-Nakata, M

AGRICULTURE-BASEL 13 巻 ( 10 ) 2023年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Agriculture (Switzerland)

This study aimed to identify superior genotypes of specialty rice (SR) with comparable or higher grain yield than the drought-tolerant check variety under rainfed and controlled-drought conditions. A total of 17 SR varieties (six aromatic, six pigmented, five glutinous) and a drought-tolerant check variety with ordinary grain quality were evaluated under rainfed lowland and controlled-drought conditions from 2019 to 2021 at Central Luzon State University in the Philippines. Among the SR varieties, aromatic NSIC Rc344, pigmented Black rice, and glutinous NSIC Rc15 had comparable or higher grain yield than the drought-tolerant check variety under both rainfed and controlled-drought conditions. These selected genotypes were classified as the highest yielding, with a more stable yield than the drought-tolerant check variety across the hydrological conditions based on the BLUPs productivity and stability test and drought tolerance indices. The selected SR varieties had a greater panicle number (NSIC Rc344), more grains per panicle (NSIC Rc15), and a higher 1000-grain weight and harvest index (Black rice). In comparison to a higher yield but with a higher market price due to the superior grain quality of the identified SR than the drought-tolerant check variety, the net income in rainfed lowland conditions significantly increased by 69–108%. These results suggest that planting good-performing SR in rainfed lowlands can increase profitability in this ecosystem due to the higher market price compared to ordinary drought-tolerant varieties.

DOI： 10.3390/agriculture13101985

Growth Performance of Photoperiod-Sensitive Rice (<i>Oryza sativa</i> L.) Varieties in Different Soil Types under Rainfed Condition in Cambodia

Uch, C; Roeurn, S; Ro, S; Kano-Nakata, M; Yamauchi, A; Ehara, H

AGRICULTURE-BASEL 13 巻 ( 8 ) 2023年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Agriculture (Switzerland)

In Cambodia, rice is predominantly produced in areas with rainfed lowland conditions where photoperiod-sensitive varieties are cultivated. A number of varieties have been released for rainfed lowland areas, and the rice grain yield has reportedly increased by approximately 12% over the past ten years. Moreover, great fluctuations in yield performance have been observed across different soil types of the rainfed ecosystems of Cambodia. Therefore, the present study aimed to analyze the grain yield and stability among ten popular varieties that were released for rainfed lowland ecosystems across the four different soil types in Cambodia in two years. The grain yield varied 566 g m−2 as the highest in clay soil and about 220 g m−2 as the lowest in sandy soil. A combined ANOVA revealed significant differences for the main effect of genotype, environment, and genotype-by-environment interaction (GEI) for all yield-related traits and grain yield per square meter. The principal component test results showed that the heterogeneity of grain yield was mainly attributable to the effect of environment, followed by the effect of genotype. In fertile conditions, a higher percentage of filled grains was supported by higher leaf N until the late stage with a wider flag leaf. In conditions of moderate fertility, larger numbers of panicles were supported by a higher percentage of productive culms with higher leaf N until the late stage. In conditions of poor fertility, a higher percentage of filled grains was supported by higher leaf N until the late stage, which is considered to be important for higher grain yield. The variety Phka Rumduol showed these preferable traits and produced higher yields in fertile to poor natural soil fertility conditions with moderate variation. This variety is considered to be more desirable and ideal due to its stability and higher grain yield. The other varieties, namely, Phka Mealdei, Phka Rumdeng, and CAR4, were identified as above-average yielders. Therefore, those varieties potentially may be recommended for cultivation in rainfed lowland rice ecosystems in Cambodia due to their high yields. CAR4 showed moderate variation at the same level as Phka Rumduol. From the point of stability, Phka Rumduol and CAR4 can be expected to excel.

DOI： 10.3390/agriculture13081602

Dry Matter Production of Two Rice Cultivars with Contrasting Root Plasticity Expression Under Different Topographic Conditions Subjected to Soil Moisture Fluctuation

Owusu-Nketia, S; Suralta, RR; Inukai, Y; Mitsuya, S; Kano-Nakata, M; Ofori, PA; Nguyen, DTN; Yamauchi, A

PHILIPPINE AGRICULTURAL SCIENTIST 106 巻 ( 2 ) 頁： 131 - 142 2023年6月

The <i>outstanding rooting1</i> mutation gene maintains shoot growth and grain yield through promoting root development in rice under water deficit field environments 査読有り国際共著

Hasegawa, T; Wainaina, CM; Shibata, A; Lucob-Agustin, N; Makihara, D; Kikuta, M; Menge, DM; Gichuhi, EW; Samejima, H; Kano-Nakata, M; Kimani, JM; Musila, RN; Yamauchi, A; Inukai, Y

JOURNAL OF AGRONOMY AND CROP SCIENCE 208 巻 ( 6 ) 頁： 815 - 829 2022年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Agronomy and Crop Science

Drought is one of the most serious constraints to rice cultivation, even under alternate wetting and drying (AWD), which is a water-saving management practice. In rice, enhanced root development is essential for stable shoot growth, adaptability and productivity under water deficit environments. We identified and characterized outstanding rooting1 (our1) rice mutant using hydroponics. The present study sought to examine morphological root traits of the our1 mutant and the role of the mutation gene in shoot growth and yield under AWD. Thus, we evaluated the growth performance of the our1 rice mutant in pot experiments and under field AWD conditions in Kenya. The experiments were conducted with our1 mutant, its wild type and their progenies under both AWD and continuously waterlogged (CWL) conditions. The our1 mutant possessed a well-developed root system and exhibited particularly enhanced thin root development, which was maintained from the early vegetative stage through the reproductive stage under both pot and field AWD management. This enhanced root development promoted shoot growth through increased water uptake during rewatered conditions between drought periods in AWD. In addition, the our1 mutant showed enhanced shoot growth during the reproductive stage, resulting in the maintenance of yield under AWD fields. Genotypes harbouring our1 mutation gene showed higher yields compared to wild-type genotypes which was attributed to their higher photosynthetic ability as a result of enhanced root activity. These results suggest the important role of a well-developed root system architecture and enhanced root function in stabilizing rice yields under water-limited environments. Our findings indicate that the our1 mutation gene can serve as a novel breeding material to mitigate the impact of transient drought stress on yield under AWD.

DOI： 10.1111/jac.12524

Grain Yield and Gross Return above Fertilizer Cost with Parameters Relating to the Quality of White Rice Cultivated in Rainfed Paddy Fields in Cambodia

Khema, S; Rin, S; Fujita, A; Kong, K; Ngin, C; Kano-Nakata, M; Yamauchi, A; Ehara, H

SUSTAINABILITY 14 巻 ( 17 ) 2022年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Sustainability (Switzerland)

This study aims to compare the grain yield, gross return above fertilizer cost (GRAFC: (paddy sales)–(fertilizer cost)), and several parameters relating to the quality of white rice cultivated with different soil-specific nutrient management in 14 provinces where different soil types are distributed. The grain yield tended to increase with increased fertilizer application; however, the relationship between the fertilization rate and the yield was not linear in areas where clay soil dominates. In cases of popular varieties cultivated from the northern to southern province, the amount of fertilizer applied was up to 163 kg ha−1 (sum of N-P2O5-K2O), and the GRAFC and the fertilization rate showed a nonlinear relationship, with a peak of around 120 kg ha−1 fertilization. The nitrogen concentration recognized as a negative factor for the quality of rice tended to increase with an increasing fertilization rate, and the carbohydrate concentration and carbohydrate/protein ratio that are a positive factor for the quality were related negatively with the fertilizer rate. The amylopectin concentration in white rice was positively related with the carbohydrate concentration, which decreased with an increasing fertilization rate. The levels of fertilizer application required to achieve a higher yield, GRAFC, and the maintenance and improvement of parameters relating to grain quality were different.

DOI： 10.3390/su141710708

Waterlogged Conditions Influence the Nitrogen, Phosphorus, Potassium, and Sugar Distribution in Sago Palm (<i>Metroxylon sagu</i> Rottb.) at Seedling Stages

Azhar, A; Asano, K; Sugiura, D; Kano-Nakata, M; Ehara, H

PLANTS-BASEL 11 巻 ( 5 ) 2022年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plants

Sago palm (Metroxylon sagu Rottb.) grows in well-drained mineral soil and in peatland with high groundwater levels until complete submersion. However, the published information on nutrient uptake and carbohydrate content in sago palms growing under waterlogging remains un-reported. This experiment observed sago palm growth performance under normal soil conditions (non-submerged conditions) as a control plot and extended waterlogged conditions. Several parameters were analyzed: Plant morphological growth traits, nitrogen, phosphorus, potassium, and sugar concentration in the plant organ, including sucrose, glucose, starch, and non-structural car-bohydrate. The analysis found that sago palm morphological growth traits were not significantly affected by extended waterlogging. However, waterlogging reduced carbohydrate levels in the up-per part of the sago palm, especially the petiole, and increased sugar levels, especially glucose, in roots. Waterlogging also reduced N concentration in roots and leaflets and P in petioles. The K level was independent of waterlogging as the sago palm maintained a sufficient level in all of the plant organs. Long duration waterlogging may reduce the plant’s economic value as the starch level in the trunk decreases, although sago palm can grow while waterlogged.

DOI： 10.3390/plants11050710

<i>WUSCHEL</i>-<i>related</i> <i>homeobox</i> family genes in rice control lateral root primordium size

Kawai, T; Shibata, K; Akahoshi, R; Nishiuchi, S; Takahashi, H; Nakazono, M; Kojima, T; Nosaka-Takahashi, M; Sato, Y; Toyoda, A; Lucob-Agustin, N; Kano-Nakata, M; Suralta, RR; Niones, JM; Chen, YL; Siddique, KHM; Yamauchi, A; Inukai, Y

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 119 巻 ( 1 ) 2022年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Proceedings of the National Academy of Sciences of the United States of America

The development of a plastic root system is essential for stable crop production under variable environments. Rice plants have two types of lateral roots (LRs): S-type (short and thin) and L-type (long, thick, and capable of further branching). LR types are determined at the primordium stage, with a larger primordium size in L-types than S-types. Despite the importance of LR types for rice adaptability to variable water conditions, molecular mechanisms underlying the primordium size control of LRs are unknown. Here, we show that two WUSCHEL-related homeobox (WOX) genes have opposing roles in controlling LR primordium (LRP) size in rice. Root tip excision on seminal roots induced L-type LR formation with wider primordia formed from an early developmental stage. QHB/OsWOX5 was isolated as a causative gene of a mutant that is defective in S-type LR formation but produces more L-type LRs than wild-type (WT) plants following root tip excision. A transcriptome analysis revealed that OsWOX10 is highly up-regulated in L-type LRPs. OsWOX10 overexpression in LRPs increased the LR diameter in an expression-dependent manner. Conversely, the mutation in OsWOX10 decreased the L-type LR diameter under mild drought conditions. The qhb mutants had higher OsWOX10 expression than WT after root tip excision. A yeast one-hybrid assay revealed that the transcriptional repressive activity of QHB was lost in qhb mutants. An electrophoresis mobility shift assay revealed that OsWOX10 is a potential target of QHB. These data suggest that QHB represses LR diameter increase, repressing OsWOX10. Our findings could help improve root system plasticity under variable environments.

DOI： 10.1073/pnas.2101846119

Utilization of Sensing and Image-processing Devices for Evaluating the Grain Quality of Cambodian Rice Varieties

SRUN Khema, FUJITA Akiko, KONG Kea, NGIN Chhay, NEOU Ratana, ASANO Koki, AUDIA Fitri, YAMADA Shuto, KANO-NAKATA Mana, YAMAUCHI Akira, TASHIRO Toru, EHARA Hiroshi

Tropical Agriculture and Development 66 巻 ( 4 ) 頁： 139 - 149 2022年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Society for Tropical Agriculture

<p>The export of Cambodian milled rice to the international market has been increasing in volume remarkably. Consumer demands for rice in terms of cooking and eating quality are different from country to county. To contribute to the promotion of Cambodian rice exports, evidence-based information about rice quality is very important. This study aims to compare the quality of eight rice samples including six different indica lowland rice varieties from different producers/suppliers in Cambodia. Some sensing equipment analyzers such as a grain scanner (image-processing device), a rice taste analyzer for white rice, and a taste analyzer unit for cooked rice that measures freshness, hardness, and stickiness using a near-infrared transmission sensor were employed with conventional chemical analyses. The percentage of head rice as analyzed by the grain scanner was over 70% in all samples, and they were evaluated as being a higher grade according to the Cambodian standard (≧ 60%). Although the analyzers were developed originally for temperate japonica, short-grain rice varieties, the taste mark detected by the analyzer for white rice showed a negative relationship with the protein and amylose content in white rice. The taste value detected by the analyzer unit for cooked rice showed a highly negative relationship with the nitrogen concentration in white rice and a highly positive relationship with the carbon/nitrogen concentration ratio—the C/N ratio—in white rice and the stickiness/hardness ratio in cooked rice.</p>

DOI： 10.11248/jsta.66.139

Arbuscular Mycorrhizal Communities in the Roots of Sago Palm in Mineral and Shallow Peat Soils

Asano, K; Kagong, WVA; Mohammad, SMB; Sakazaki, K; Abu Talip, MS; Sahmat, SS; Chan, MKY; Isoi, T; Kano-Nakata, M; Ehara, H

AGRICULTURE-BASEL 11 巻 ( 11 ) 2021年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Agriculture (Switzerland)

Communities of arbuscular mycorrhizal fungi (AMF) in plant roots improve host plant growth. In this study, AMF communities in the roots of the sago palm (Metroxylon sagu Rottb.) were investigated in mineral soil (MS) and shallow peat soil (SPS) in Sarawak, Malaysia. MS exhibited lower moisture content (MS, 38.1; SPS, 79.8%), higher pH (H2 O) (MS, 4.6; SPS, 4.1), higher soil bulk density (MS, 1.03; SPS, 0.20 g cm−3 ), and higher nitrogen content (MS, 16.9; SPS, 2.7 kg m−3 ) than SPS at the same soil depth, while the phosphorus (P) content (Bray II) (MS, 1.6; SPS, 1.9 g P2 O5 m−3 ) was similar. The AMF colonization rate was significantly lower in SPS (39.2 ± 12.5%) than in MS (73.2 ± 4.6%). The higher number of AMF operational taxonomic units (OTUs) was detected by amplicon sequencing of the partial small-subunit rRNA gene (MS, 78; SPS, 50). A neighbor-joining tree of obtained OTUs revealed that they belonged to Acaulosporaceae, Ambisporaceae, Claroideoglomeraceae, Gigasporaceae, and Glomeraceae. The lower abundance and diversity of AMF in SPS are possibly caused by abiotic factors, including soil physicochemical properties. Glomus and Acaulospora species detected in SPS might have strong tolerance against acidity and high soil moisture content.

DOI： 10.3390/agriculture11111161

Mutation of OUR1/OsbZIP1, which encodes a member of the basic leucine zipper transcription factor family, promotes root development in rice through repressing auxin signaling 査読有り国際誌

Hasegawa, T; Lucob-Agustin, N; Yasufuku, K; Kojima, T; Nishiuchi, S; Ogawa, A; Takahashi-Nosaka, M; Kano-Nakata, M; Inari-Ikeda, M; Sato, M; Tsuji, H; Wainaina, CM; Yamauchi, A; Inukai, Y

PLANT SCIENCE 306 巻頁： 110861 - 110861 2021年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plant Science

A well-developed root system is essential for efficient water uptake, particularly in drought-prone environments. However, the molecular mechanisms underlying the promotion of root development are poorly understood. We identified and characterized a rice mutant, outstanding rooting1 (our1), which exhibited a well-developed root system. The our1 mutant displayed typical auxin-related phenotypes, including elongated seminal root and defective gravitropism. Seminal root elongation in the our1 mutant was accelerated via the promotion of cell division and elongation. In addition, compared with the wild type, the density of short and thin lateral roots (S-type LRs) was reduced in the our1 mutant, whereas that of long and thick LRs (L-type LRs) was increased. Expression of OUR1, which encodes OsbZIP1, a member of the basic leucine zipper transcription factor family, was observed in the seminal root tip and sites of LR emergence, wherein attenuation of reporter gene expression levels controlled by the auxin response promoter DR5 was also observed in the our1 mutant. Taken together, our results indicate that the our1 gene promotes root development by suppressing auxin signaling, which may be a key factor contributing to an improvement in root architecture.

DOI： 10.1016/j.plantsci.2021.110861

Root system characteristics under different water regimes in three cereal species 査読有り国際共著

Natsumi Ueda, Shiro Mitsuya, Akira Yamauchi, Maria Corazon J. Cabral and Mana Kano-Nakata

PLANT ROOT 15 巻頁： 9 - 17 2021年4月

Morpho-physiological and molecular mechanisms of phenotypic root plasticity for rice adaptation to water stress conditions

Lucob-Agustin, N; Kawai, T; Kano-Nakata, M; Suralta, RR; Niones, JM; Hasegawa, T; Inari-Ikeda, M; Yamauchi, A; Inukai, Y

BREEDING SCIENCE 71 巻 ( 1 ) 頁： 20 - 29 2021年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：日本育種学会

Different types of water stress severely affect crop production, and the plant root system plays a critical role in stress avoidance. In the case of rice, a cereal crop cultivated under the widest range of soil hydrologic conditions, from irrigated anaerobic conditions to rainfed conditions, phenotypic root plasticity is of particular relevance. Recently, important plastic root traits under different water stress conditions, and their physiological and molecular mechanisms have been gradually understood. In this review, we summarize these plastic root traits and their contributions to dry matter production through enhancement of water uptake under different water stress conditions. We also discuss the physiological and molecular mechanisms regulating the phenotypic plasticity of root systems.

DOI： 10.1270/jsbbs.20106

The <i>promoted lateral root 1</i> (<i>plr1</i>) mutation is involved in reduced basal shoot starch accumulation and increased root sugars for enhanced lateral root growth in rice 国際誌

Lucob-Agustin, N; Sugiura, D; Kano-Nakata, M; Hasegawa, T; Suralta, RR; Niones, JM; Inari-Ikeda, M; Yamauchi, A; Inukai, Y

PLANT SCIENCE 301 巻頁： 110667 - 110667 2020年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Plant Science

Lateral roots (LRs) are indispensable for plant growth, adaptability and productivity. We previously reported a rice mutant, exhibiting a high density of thick and long LRs (L-type LRs) with long parental roots and herein referred to as promoted lateral root1 (plr1). In this study, we describe that the mutant exhibited decreased basal shoot starch accumulation, suggesting that carbohydrates might regulate the mutant root phenotype. Further analysis revealed that plr1 mutation gene regulated reduced starch accumulation resulting in increased root sugars for the regulation of promoted LR development. This was supported by the exogenous glucose application that promoted L-type LRs. Moreover, nitrogen (N) application was found to reduce basal shoot starch accumulation in both plr1 mutant and wild-type seedlings, which was due to the repressed expression of starch biosynthesis genes. However, unlike the wild-type that responded to N treatment only at seedling stage, the plr1 mutant regulated LR development under low to increasing N levels, both at seedling and higher growth stages. These results suggest that plr1 mutation gene is involved in reduced basal shoot starch accumulation and increased root sugar level for the promotion of L-type LR development, and thus would be very useful in improving rice root architecture.

DOI： 10.1016/j.plantsci.2020.110667

A GWAS approach to find SNPs associated with salt removal in rice leaf sheath

Neang, S; de Ocampo, M; Egdane, JA; Platten, JD; Ismail, AM; Seki, M; Suzuki, Y; Skoulding, NS; Kano-Nakata, M; Yamauchi, A; Mitsuya, S

ANNALS OF BOTANY 126 巻 ( 7 ) 頁： 1193 - 1202 2020年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Annals of Botany

Background and Aims: The ability for salt removal at the leaf sheath level is considered to be one of the major mechanisms associated with salt tolerance in rice. Thus, understanding the genetic control of the salt removal capacity in leaf sheaths will help improve the molecular breeding of salt-tolerant rice varieties and speed up future varietal development to increase productivity in salt-affected areas. We report a genome-wide association study (GWAS) conducted to find single nucleotide polymorphisms (SNPs) associated with salt removal in leaf sheaths of rice. Methods: In this study, 296 accessions of a rice (Oryza sativa) diversity panel were used to identify salt removal-related traits and conduct GWAS using 36 901 SNPs. The sheath:blade ratio of Na+ and Cl- concentrations was used to determine the salt removal ability in leaf sheaths. Candidate genes were further narrowed via Gene Ontology and RNA-seq analysis to those whose putative function was likely to be associated with salt transport and were up-regulated in response to salt stress. Key results: For the association signals of the Na+ sheath:blade ratio, significant SNPs were found only in the indica sub-population on chromosome 5. Within candidate genes found in the GWAS study, five genes were upregulated and eight genes were downregulated in the internal leaf sheath tissues in the presence of salt stress. Conclusions: These GWAS data imply that rice accessions in the indica variety group are the main source of genes and alleles associated with Na+ removal in leaf sheaths of rice under salt stress.

DOI： 10.1093/aob/mcaa139

Tissue-specific expression analysis of Na<SUP>+</SUP> and Cl<SUP>-</SUP> transporter genes associated with salt removal ability in rice leaf sheath 国際誌

Neang, S; Goto, I; Skoulding, NS; Cartagena, JA; Kano-Nakata, M; Yamauchi, A; Mitsuya, S

BMC PLANT BIOLOGY 20 巻 ( 1 ) 頁： 502 - 502 2020年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：BMC Plant Biology

Background: A significant mechanism of salt-tolerance in rice is the ability to remove Na+ and Cl− in the leaf sheath, which limits the entry of these toxic ions into the leaf blade. The leaf sheath removes Na+ mainly in the basal parts, and Cl− mainly in the apical parts. These ions are unloaded from the xylem vessels in the peripheral part and sequestered into the fundamental parenchyma cells at the central part of the leaf sheath. Results: This study aimed to identify associated Na+ and Cl− transporter genes with this salt removal ability in the leaf sheath of rice variety FL 478. From 21 known candidate Na+ and Cl− transporter rice genes, we determined the salt responsiveness of the expression of these genes in the basal and apical parts, where Na+ or Cl− ions were highly accumulated under salinity. We also compared the expression levels of these transporter genes between the peripheral and central parts of leaf sheaths. The expression of 8 Na+ transporter genes and 3 Cl− transporter genes was up-regulated in the basal and apical parts of leaf sheaths under salinity. Within these genes, OsHKT1;5 and OsSLAH1 were expressed highly in the peripheral part, indicating the involvement of these genes in Na+ and Cl− unloading from xylem vessels. OsNHX2, OsNHX3, OsNPF2.4 were expressed highly in the central part, which suggests that these genes may function in sequestration of Na+ and Cl− in fundamental parenchyma cells in the central part of leaf sheaths under salinity. Furthermore, high expression levels of 4 candidate genes under salinity were associated with the genotypic variation of salt removal ability in the leaf sheath. Conclusions: These results indicate that the salt removal ability in rice leaf sheath may be regulated by expressing various Na+ or Cl− transporter genes tissue-specifically in peripheral and central parts. Moreover, some genes were identified as candidates whose expression levels were associated with the genotypic variation of salt removal ability in the leaf sheath. These findings will enhance the understanding of the molecular mechanism of salt removal ability in rice leaf sheath, which is useful for breeding salt-tolerant rice varieties.

DOI： 10.1186/s12870-020-02718-4

Plasticity in Nodal Root Hardpan Penetration, Deep Soil Water Uptake, and Shoot Dry Matter Production under Soil Moisture Fluctuations Using Chromosome Segment Substitution Lines of Rice

Nguyen, DTN; Suralta, RR; Kano-Nakata, M; Mitsuya, S; Owusu-Nketia, S; Yamauchi, A

PHILIPPINE AGRICULTURAL SCIENTIST 103 巻 ( 3 ) 頁： 214 - 234 2020年9月

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