Faculty Profiles - KANO-NAKATA Mana

Papers - KANO-NAKATA Mana

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

Vol. 2 ( 4 ) page： 202 - 208 2023.12

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

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

AGRICULTURE-BASEL Vol. 13 ( 10 ) 2023.10

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：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 Reviewed International coauthorship

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

AGRICULTURE-BASEL Vol. 13 ( 8 ) 2023.8

Language：English Publishing type：Research paper (scientific journal) Publisher：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 Reviewed International coauthorship

Owusu-Nketia S., Suralta R.R., Inukai Y., Mitsuya S., Kano-Nakata M., Ofori P.A., Nguyen D.T.N., Yamauchi A.

Philippine Agricultural Scientist Vol. 106 ( 2 ) page： 131 - 142 2023.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Philippine Agricultural Scientist

In rainfed lowland rice fields characterized by sloping terrains and the presence of a hardpan in a flat topography, plants are often exposed to soil moisture fluctuation (SMF) stress due to erratic rainfall patterns. Root plasticity is one of the key traits that play important roles in plant adaptation under such conditions. In this study, two contrasting genotypes, KDML105 and IRAT109, were examined to quantify the expression of plasticity in root branching at different positions in the toposequence (TP) and in a flat topography with a hardpan, both without a groundwater table, and subjected to SMF. Results showed that KDML105 exhibited improved adaptation to SMF conditions due to its greater root system because of the promoted nodal root production and development of lateral roots in the upper soil layer (0 – 20 cm soil depth) along the TP and above the hardpan in a flat topography, which led to the maintenance of its stomatal conductance and dry matter production. IRAT109, on the other hand, did not express root plasticity in deep-rooting due to the absence of groundwater table, particularly in the upper TP, as well as branching ability above the hardpan in a flat topography, which resulted in less water uptake and reduced dry matter production under SMF. Overall, the results indicated that root plasticity in the upper soil layer could be an important trait for the adaptation of rice, both in a sloping TP without a hardpan or in a flat topography with a hardpan, experiencing SMF.

The outstanding rooting1 mutation gene maintains shoot growth and grain yield through promoting root development in rice under water deficit field environments

Tomomi Hasegawa, Cornelius Mbathi Wainaina, Akihide Shibata, Nonawin Lucob-Agustin, Daigo Makihara, Mayumi Kikuta, Daniel Makori Menge, Emily Waringa Gichuhi, Hiroaki Samejima, Mana Kano-Nakata, John Munji Kimani, Ruth Nzisa Musila, Akira Yamauchi, Yoshiaki Inukai

JOURNAL OF AGRONOMY AND CROP SCIENCE Vol. 208 ( 6 ) page： 815 - 829 2022.12

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

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 Reviewed International coauthorship

Khema Srun, Rin Soriya, Fujita Akiko, Kong Kea, Ngin Chhay, Kano-Nakata Mana, Yamauchi Akira, Ehara Hiroshi

SUSTAINABILITY Vol. 14 ( 17 ) 2022.9

Language：English Publishing type：Research paper (scientific journal) Publisher：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 (Metroxylon sagu Rottb.) at Seedling Stages Reviewed International coauthorship

Azhar Aidil, Asano Koki, Sugiura Daisuke, Kano-Nakata Mana, Ehara Hiroshi

PLANTS-BASEL Vol. 11 ( 5 ) 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：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

WUSCHEL-related homeobox family genes in rice control lateral root primordium size Reviewed International coauthorship

Kawai Tsubasa, Shibata Kyosuke, Akahoshi Ryosuke, Nishiuchi Shunsaku, Takahashi Hirokazu, Nakazono Mikio, Kojima Takaaki, Nosaka-Takahashi Misuzu, Sato Yutaka, Toyoda Atsushi, Lucob-Agustin Nonawin, Kano-Nakata Mana, Suralta Roel R., Niones Jonathan M., Chen Yinglong, Siddique Kadambot H. M., Yamauchi Akira, Inukai Yoshiaki

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Vol. 119 ( 1 ) 2022.1

Language：English Publishing type：Research paper (scientific journal) Publisher：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 Reviewed International coauthorship

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 Vol. 66 ( 4 ) page： 139 - 149 2022

Language：English Publishing type：Research paper (scientific journal) Publisher：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 Reviewed International coauthorship

Asano Koki, Kagong Willy Vincent Anak, Mohammad Siraj Munir Bin, Sakazaki Kurumi, Abu Talip Muhamad Syukrie, Sahmat Siti Sahmsiah, Chan Margaret Kit Yok, Isoi Toshiyuki, Kano-Nakata Mana, Ehara Hiroshi

AGRICULTURE-BASEL Vol. 11 ( 11 ) 2021.11

Language：English Publishing type：Research paper (scientific journal) Publisher：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. Reviewed International coauthorship International journal

Tomomi Hasegawa, Nonawin Lucob-Agustin, Koki Yasufuku, Takaaki Kojima, Shunsaku Nishiuchi, Atsushi Ogawa, Misuzu Takahashi-Nosaka, Mana Kano-Nakata, Mayuko Inari-Ikeda, Moeko Sato, Hiroyuki Tsuji, Cornelius Mbathi Wainaina, Akira Yamauchi, Yoshiaki Inukai

Vol. 306 page： 110861 - 110861 2021.5

Language：English Publishing type：Research paper (scientific journal)

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 Reviewed International coauthorship

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

Plant Root Vol. 15 ( 0 ) page： 10 - 18 2021

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Root Research

<p>Water stress such as drought and waterlogging is considered to be a major limiting factor in crop production. Roots play important roles in crop adaptation to water stress. This study aimed to characterize the vertical root distribution patterns and analyze the root-shoot relationships of different cereal species with different water requirements in response to different soil moisture conditions. Sorghum, maize, and rice were grown under 5% w/w soil moisture content (SMC5), 20% w/w soil moisture content (SMC20) and in waterlogged soil (WL) for 35 days using root box pin-board method. For sorghum and maize, the optimal soil water condition was SMC20 which produced the greatest shoot and root growth, while rice had greatest shoot and root growth under WL. Sorghum significantly increased root to shoot ratio in both water stress conditions, suggesting that sorghum prioritizes carbon partitioning of assimilates towards the roots. Although whole root dry weight and total root length were reduced by water stress, vertical distribution of root traits varied with soil water conditions and promoted root response was observed in specific soil layer. A highly positive relationship between root and shoot traits was observed in rice, suggesting that root and shoot trait responses are coupled with changing soil water conditions. Further studies are needed to confirm root architectural changes focusing on different root component traits as well as other root traits related to root architectural structure.</p>

DOI： 10.3117/plantroot.15.10

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 Reviewed International coauthorship

Nguyen D.T.N., Suralta R.R., Kano-Nakata M., Mitsuya S., Owusu-Nketia S., Yamauchi A.

Philippine Agricultural Scientist Vol. 103 ( 4 ) page： 337 - 348 2020.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Philippine Agricultural Scientist

Rainfed lowland (RFL) fields generally experience soil moisture fluctuations (SMF) and have a hardpan layer that impedes deep rooting during episodes of drought. The development of root systems in response to SMF and the ability of roots to elongate through the hardpan when it becomes relatively soft during re-watering are key rice traits to efficiently extract water at the deep soil during subsequent periods of drought. Thus, this study aimed to identify their chromosome segment substitution lines (CSSLs) from Sasanishiki and Habataki crosses, which have root plasticity exhibited in response to SMF, which enables plants to penetrate the hardpan and develop deep root systems. Root plasticity was evaluated by comparing root traits between each of the 39 CSSLs and their recurrent parent, Sasanishiki, under water-stressed and well-watered (WW control) conditions in hydroponics and soil-filled pots. Among the 39 CSSLs, three (SL34, SL35 and SL39) had similar growth as Sasanishiki under WW, but were able to produce greater shoot dry weight than their recurrent parent under transient soil moisture stress in hydroponics and soil culture. Under SMF, in the rootbox-pinboard and rootbox-hardpan systems, only SL39 showed a significantly greater root system development than Sasanishiki. SL39 also had a more enhanced root aerenchyma formation than Sasanishiki in the shallow layer during drought-rewatered conditions under SMF, possibly facilitating atmospheric O2 diffusion to the root tips. As a consequence, SL39 promoted nodal root elongation through the hardpan during rewatering and subsequent greater deep root system development to access more water from the deep soil during the drought period of SMF, relative to Sasanishiki. The results implied that SL39 can be a good genetic material to study the QTLs associated with plasticity in root hardpan penetration and deep root system development in rice.

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

Neang Sarin, de Ocampo Marjorie, Egdane James A., Platten John Damien, Ismail Abdelbagi M., Seki Masahide, Suzuki Yutaka, Skoulding Nicola Stephanie, Kano-Nakata Mana, Yamauchi Akira, Mitsuya Shiro

ANNALS OF BOTANY Vol. 126 ( 7 ) page： 1193 - 1202 2020.11

Language：English Publishing type：Research paper (scientific journal) Publisher：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

WEG1, which encodes a cell wall hydroxyproline-rich glycoprotein, is essential for parental root elongation controlling lateral root formation in rice Reviewed International coauthorship

Lucob-Agustina Nonawin, Kawai Tsubasa, Takahashi-Nosaka Misuzu, Kano-Nakata Mana, Wainaina Cornelius M., Hasegawa Tomomi, Inari-Ikeda Mayuko, Sato Moeko, Tsuji Hiroyuki, Yamauchi Akira, Inukai Yoshiaki

PHYSIOLOGIA PLANTARUM Vol. 169 ( 2 ) page： 214 - 227 2020.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Physiologia Plantarum

Lateral roots (LRs) determine the overall root system architecture, thus enabling plants to efficiently explore their underground environment for water and nutrients. However, the mechanisms regulating LR development are poorly understood in monocotyledonous plants. We characterized a rice mutant, wavy root elongation growth 1 (weg1), that produced higher number of long and thick LRs (L-type LRs) formed from the curvatures of its wavy parental roots caused by asymmetric cell growth in the elongation zone. Consistent with this phenotype, was the expression of the WEG1 gene, which encodes a putative member of the hydroxyproline-rich glycoprotein family that regulates cell wall extensibility, in the root elongation zone. The asymmetric elongation growth in roots is well known to be regulated by auxin, but we found that the distribution of auxin at the apical region of the mutant and the wild-type roots was symmetric suggesting that the wavy root phenotype in rice is independent of auxin. However, the accumulation of auxin at the convex side of the curvatures, the site of L-type LR formation, suggested that auxin likely induced the formation of L-type LRs. This was supported by the need of a high amount of exogenous auxin to induce the formation of L-type LRs. These results suggest that the MNU-induced weg1 mutated gene regulates the auxin-independent parental root elongation that controls the number of likely auxin-induced L-type LRs, thus reflecting its importance in improving rice root architecture.

DOI： 10.1111/ppl.13063

Morphological and histological differences among three types of component roots and their differential contribution to water uptake in the rice root system Reviewed International coauthorship

Watanabe Yumika, Kabuki Takuya, Kakehashi Takahiro, Kano-Nakata Mana, Mitsuya Shiro, Yamauchi Akira

PLANT PRODUCTION SCIENCE Vol. 23 ( 2 ) page： 191 - 201 2020.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Plant Production Science

The rice root system consists of three types of roots; main root, L-type and S-type lateral root (LR). These component roots are morphologically and histologically different, which is termed as heterorhizy. Root system hydraulic architecture is related to the unique features of component roots. We hypothesized that each component root contributes in different degrees to water uptake of the whole root system. Rice varieties IRAT 109 and Taichung 65 were grown in pots filled with soil under continuous waterlogged (CWL) and drought (CD) conditions until two weeks after heading. Morphology and histological structures of roots, which may regulate radial water movement, were compared among the three component roots. Moreover, hydraulic conductivity (Lpr) of the root system, which represents the water uptake ability, were measured with a pressure chamber. Based on a model that Lpr of the whole root system is a product of Lpr of each of the component roots and their surface areas, we found that the differences in Lpr between the two varieties and the plants grown under different soil water conditions for any of the component roots did not support the corresponding differences in the measured Lpr of the whole root system. In contrast, a significant and positive correlation was found between Lpr of the whole root system and the percentage of surface area of S-type LR but not for the other component roots. These results indicate S-type LR might have a higher contribution to Lpr of the whole root system than the other component roots.

DOI： 10.1080/1343943X.2020.1730701

‘Kasalath’ allele in nipponbare background is responsible for the plasticity in lateral root development of rice under soil moisture fluctuation stress Reviewed International coauthorship

Niones J.M., Suralta R.R., Inukai Y., Kano-Nakata M., Yamauchi A.

Philippine Agricultural Scientist Vol. 102 ( 3 ) page： 188 - 198 2019.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Philippine Agricultural Scientist

Soil moisture fluctuations (SMF) from wet to dry and vice-versa are common under field conditions, which influence root growth and functions and thus dry matter production and yield. In such condition, phenotypic plasticity in L-type lateral root (LLR) development is an adaptive mechanism of rice and the associated quantitative trait locus (QTL) was previously detected in chromosome 12, mainly contributed by the ‘Kasalath’ allele in Nipponbare x Kasalath chromosome segment substitution lines (CSSLs). In this study, we used +qLLRN-12 genotype of Nipponbare background to validate the functions for LR plasticity under SMF and progressive drought. Plants were subjected to well-watered, fluctuating soil moisture and progressive drought conditions for 38 d. There were no significant genotypic differences in shoot growth and root development under well-watered condition. On the other hand, +qLLRN-12 genotype showed greater shoot dry weight by 31% than Nipponbare, which was associated with larger root system of the former than the latter genotype under fluctuating soil moistures. The greater root system development of +qLLRN-12 genotype was attributed to the greater L-type LR development by 95% relative to Nipponbare. However, under progressive drought condition, +qLLRN-12 genotype had reduced shoot dry weight (SDW) due to its smaller root system relative to its fluctuating soil moisture and well-watered counterparts. These results indicate that the introgressed segment of Kasalath on the chromosome 12 region of Nipponbare was responsible for the plasticity in L-type LR, which contributed to greater root system development, increased water uptake and consequently increased dry matter production under fluctuating soil moisture conditions. The findings also suggest that the expression of this allele is unique and triggered only under fluctuating moisture stress conditions.

Fundamental parenchyma cells are involved in Na+ and Cl- removal ability in rice leaf sheath Reviewed International coauthorship

Neang Sarin, de Ocampo Marjorie, Egdane James A., Platten John D., Ismail Abdelbagi M., Skoulding Nicola S., Kano-Nakata Mana, Yamauchi Akira, Mitsuya Shiro

FUNCTIONAL PLANT BIOLOGY Vol. 46 ( 8 ) page： 743 - 755 2019

Language：English Publishing type：Research paper (scientific journal) Publisher：Functional Plant Biology

Salt sensitivity in rice plants is associated with the accumulated amount of Na+ and Cl- in shoots and, more significantly, in photosynthetic tissues. Therefore, salt removal ability at the leaf sheath level is an important mechanism of salt tolerance. In the present study we attempted to determine whether rice leaf sheaths excluded Cl- as well as Na+, and to identify the tissues that were involved in the removal ability of both ions. In two rice genotypes, salt-tolerant FL478 and -sensitive IR29, leaf sheaths excluded Na+ and Cl- under NaCl treatment as estimated using their sheath: blade ratios. The sheath: blade ratio of Na+ but not of Cl-, was increased by NaCl treatment. Under NaCl treatment, Na+ concentration was higher in the basal leaf sheath, whereas Cl- concentration was higher in the middle and tip parts. At the tissue level, fundamental parenchyma cells of leaf sheaths retained the highest amounts of Na and Cl when treated with high amount of NaCl. These results imply that the leaf sheath potentially functions to remove excess Na+ and Cl- from xylem vessels in different locations along the axis, with the fundamental parenchyma cells of leaf sheaths being involved in over-accumulation of both Na+ and Cl-.

DOI： 10.1071/FP18318

Drought-induced root plasticity of two upland NERICA varieties under conditions with contrasting soil depth characteristics. Reviewed International coauthorship

Menge, D.M., Kameoka, E., Kano-Nakata, M., Yamauchi, A., Asanuma, S., Asai, H., Kikuta, M., Suralta, R.R., Koyama, T., Tran, T.T., Siopongco, J.D.L.C., Mitsuya, S., Inukai, Y. and Makihara, D.

Plant Production Science Vol. 19 page： 389 - 400 2016

Root system characteristics under different water regimes in three cereal species Reviewed International coauthorship

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

PLANT ROOT Vol. 15 page： 9 - 17 2021.3

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