Springer Science and Business Media LLC Acta Medica Okayama 0014-2336 220 2 2024 Tamyb10-D1 restores red grain color and increases grain dormancy via suppressing expression of TaLTP2.128, non-specific lipid transfer protein in wheat 16 EN Eiko Himi Kibi International University Shiho Kurihara-Yonemoto Hokkaido Agricultural Research Center, National Agriculture and Food Research Organization Fumitaka Abe Institute of Crop Science, National Agriculture and Food Research Organization Hidekazu Takahashi Fukushima University Keisuke Tanaka NODAI Genome Research Center, Tokyo University of Agriculture Takakazu Matsuura Institute of Plant Science and Resources, Okayama University Masahiko Maekawa Institute of Plant Science and Resources, Okayama University Takuji Sasaki NODAI Research Institute, Tokyo University of Agriculture Kazuhide Rikiishi Institute of Plant Science and Resources, Okayama University Grain dormancy of wheat is closely associated with grain color: red-grained lines show higher dormancy than white-grained lines. The production of red pigments is regulated by R-1, Tamyb10 gene. However, the relation between grain color and dormancy remains unknown. For this study, we generated transgenic lines which were introduced a DNA fragment containing Tamyb10-D1 gene and its a 2 kb promoter including the 5′ untranslated region into white-grained wheat. Transgenic lines showed red-grained and higher dormant traits. Contents of plant hormones and gene expression of embryos at 30 days after pollination were examined in a wild type and a transgenic line. No differences were observed in the contents of plant hormones, but several genes are differentially expressed between these lines. One differentially expressed gene, TaLTP2.128, is a member of non-specific lipid transfer proteins. It was expressed higher in white grains than in red grains. A putative amino acid sequence showed similarity to that of OsHyPRP5, which is identified as QTL controlling low-temperature germinability in rice. Expression of TaLTP2.128 was increased by grain imbibition. The increasing levels were higher not only in other white-grained lines, but also in non-dormant red-grained lines. TaLTP2.128 was expressed at a quite early stage of germination. These study findings indicate that Tamyb10 regulates dormancy release by the modification of TaLTP2.128 acting as trigger of germination. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2076-3921 11 9 2022 Rice Nudix Hydrolase OsNUDX2 Sanitizes Oxidized Nucleotides 1805 EN Yuki Kondo Institute of Plant Science and Resources, Okayama University Kazuhide Rikiishi Institute of Plant Science and Resources, Okayama University Manabu Sugimoto Institute of Plant Science and Resources, Okayama University Nudix hydrolase (NUDX) hydrolyzes 8-oxo-(d)GTP to reduce the levels of oxidized nucleotides in the cells. 8-oxo-(d)GTP produced by reactive oxygen species (ROS) is incorporated into DNA/RNA and mispaired with adenine, causing replicational and transcriptional errors. Here, we identified a rice OsNUDX2 gene, whose expression level was increased 15-fold under UV-C irradiation. The open reading frame of the OsNUDX2 gene, which encodes 776 amino acid residues, was cloned into Escherichia coli cells to produce the protein of 100 kDa. The recombinant protein hydrolyzed 8-oxo-dGTP, in addition to dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP), as did Arabidopsis AtNUDX1; whereas the amino acid sequence of OsNUDX2 had 18% identity with AtNUDX1. OsNUDX2 had 14% identity with barley HvNUDX12, which hydrolyzes 8-oxo-dGTP and diadenosine tetraphosphates. Suppression of the lacZ amber mutation caused by the incorporation of 8-oxo-GTP into mRNA was prevented to a significant degree when the OsNUDX2 gene was expressed in mutT-deficient E. coli cells. These results suggest that the different substrate specificity and identity among plant 8-oxo-dGTP-hydrolyzing NUDXs and OsNUDX2 reduces UV stress by sanitizing the oxidized nucleotides. No potential conflict of interest relevant to this article was reported.

Japanese Society of Breeding Acta Medica Okayama 1344-7610 71 2 2021 Transcriptomic analysis of developing seeds in a wheat (Triticum aestivum L.) mutant RSD32 with reduced seed dormancy 155 166 EN Kazuhide Rikiishi Manabu Sugimoto Institute of Plant Science and Resources, Okayama University Masahiko Maekawa Institute of Plant Science and Resources, Okayama University Seed dormancy, a major factor regulating pre-harvest sprouting, can severely hinder wheat cultivation. Reduced Seed Dormancy 32 (RSD32), a wheat (Triticum aestivum L.) mutant with reduced seed dormancy, is derived from the pre-harvest sprouting tolerant cultivar, 'Norin61'. RSD32 is regulated by a single recessive gene and mutant phenotype expressed in a seed-specific manner. Gene expressions in embryos of 'Norin61' and RSD32 were compared using RNA sequencing (RNA-seq) analysis at different developmental stages of 20, 30, and 40 days after pollination (DAP). Numbers of up-regulated genes in RSD32 are equivalent in all developmental stages. However, down-regulated genes in RSD32 are more numerous on DAP20 and DAP30 than on DAP40. In central components affecting the circadian clock, homologues to the morning-expressed genes are expressed at lower levels in RSD32. However, higher expressions of homologues acting as evening-expressed genes are observed in RSD32. Homologues of Ca2+ signaling pathway related genes are specifically expressed on DAP20 in 'Norin61'. Lower expression is shown in RSD32. These results suggest that RSD32 mutation expresses on DAP20 and earlier seed developmental stages and suggest that circadian clock regulation and Ca2+ signaling pathway are involved in the regulation of wheat seed dormancy. No potential conflict of interest relevant to this article was reported.

Public Library Science Acta Medica Okayama 1932-6203 9 9 2014 Seed Maturation Regulators Are Related to the Control of Seed Dormancy in Wheat (Triticum aestivum L.) EN Kazuhide Rikiishi Masahiko Maekawa In Arabidopsis, the regulation network of the seed maturation program controls the induction of seed dormancy. Wheat EST sequences showing homology with the master regulators of seed maturation, LEAFY COTYLEDON1 (LEC1), LEC2 and FUSCA3 (FUS3), were searched from databases and designated respectively as TaL1L (LEC1-LIKE), TaL2L (LEC2-LIKE), and TaFUS3. TaL1LA, TaL2LA and TaFUS3 mainly expressed in seeds or embryos, with the expression limited to the early stages of seed development. Results show that tissue-specific and developmental-stage-dependent expressions are similar to those of seed maturation regulators in Arabidopsis. In wheat cultivars, the expression level of TaL1LA is correlated significantly with the germination index (GI) of whole seeds at 40 days after pollination (DAP) (r = -0.83**). Expression levels of TaFUS3 and TaL2LA are significantly correlated respectively with GIs at 40 DAP and 50 DAP, except for dormant cultivars. No correlation was found between the expression level of TaVP1, orthologue of ABA INSENSITIVE3 (ABI3), and seed dormancy. DELAY OF GERMINATION1 (DOG1) was identified as a quantitative trait locus (QTL) for the regulation of seed dormancy in Arabidopsis. Its promoter has RY motif, which is a target sequence of LEC2. Significant correlation was found between the expression of TaDOG1 and seed dormancy except for dormant cultivars. These results indicate that TaL1LA, TaL2LA, and TaFUS3 are wheat orthologues of seed maturation regulators. The expressions of these genes affect the level of seed dormancy. Furthermore, the pathways, which involve seed maturation regulators and TaDOG1, are important for regulating seed dormancy in wheat. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 3 1 1995 オオムギの近辺野生種と栽培種における未熟胚由来カルスからの再分化能の比較 55 62 EN Kazuhide Rikiishi Kazuyoshi Takeda Shozo Yasuda The variation in shoot regeneration obility of calli derived from immature embryos was examined in 95 wild strains, 82 of which were of Hordeum spontaneum and 13 of which were H. agriocrithon, and 87 cultivated varieties collected from various countries or regions of the world. In 85 strains of the wild species, a number of calli regenerated shoots, and their proportion ranged from 1.2% to 75.7%. The average percentage of shoot regenerating calli was 21.7% among the strains that formed calli, 11.5% of which regenerated green and 10.2% albino shoots. On average, 21.4% and 23.9% calli regenerated shoots in H. spontaneum and H. agriocrithon, respectively and there was no significant difference between these values. A significant difference in the percentage of shoot regenerating calli was found among six variants (dawense, ishnatherum, laguncliforme, paradoxon, proskowetzii, spontaneum) which were comprised in H. spontaneum. In 73 varieties of cultivated species, there were shoots regenerating calli likely to wild species, and their proportion ranged from 3.2% to 85.5%. The average percentage of shoot regenerating calli was 25.4%, 22.0% of which regenerated green and 3.4% of which regenerated albino shoots. There was a significant difference in percentage of green shoots regenerating calli against shoots regenerating ones between the wild (53.0%) and cultivated species 886.6%). The two kinds of non-brittle rachis genotypes, Bt bt2 and bt Bt2 are one of the key characters distinguishing the oriental and occidental types of cultivated barley. The average percentages of shoot regenerating calli were 16.2% and 32.3% for the genotypes Bt bt2 and bt Bt2, respectively, suggesting that there is a geographical variation in the shoot regeneration ability of calli in the cultivated species. By contrast, the oriental and occidental strains of wild species showed no difference in the shoot regeneration ability of calli. The geographical variation of shoot regeneration ability differed significantly between wild and cultivated species. This suggests that the geographical variation of shoot regeneration ability occurred after the cultivation of the barley was established. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 2 1 1994 オオムギ未熟胚培養系におけるカルス生長量及び植物体再分化能の遺伝解析 43 53 EN Yoshiro Mano Kazuhide Rikiishi Shozo Yasuda Immature embryos of 99 varieties of barley were cultured to investigate the ability of callus growth and plant regeneration. These two in vitro traits showed wide and continuous variations among the barley varieties tested. Ability of callus growth, which were evaluated by callus diameter ranged from 3.9mm to 11.2mm, and ability of plant regeneration from the calli ranged from 0% to 100%. A set of complete diallel crosses was made using six cultivars as the parents which differed in ability of callus growth and plant regeneration. The Vr/Wr graphical analysis showed that there were epistasis, or interaction among nonallelic genes for callus growth. As to ability of plant regeneration, no epistasis existed in the subdiallel without P1 (J232) which showed high specific combining ability, and it was controlled by a simple additive dominance genetic system. The mean degree of dominance(0.42) was relatively low and the broad(0.86) and narrow(0.78) sense heritabilities were high. No potential conflict of interest relevant to this article was reported.

岡山大学資源生物科学研究所 Acta Medica Okayama 0916-930X 2 1 1994 オオムギ品種における完熟胚および未熟胚由来カルスの再分化能の比較 33 42 EN Kazuhide Rikiishi Shozo Yasuda The callus forming ability and regenerating ability of the calli derived from mature and immature embryos of 132 barley varieties were examined. These materials were taken from a world-wide collection preserved at the Barley Germplasm Center of Okayama University. The callus forming ability varied widely according to genotype in both mature and immature embryos, but the varieties collected from Ethiopia showed low callus forming ability. Calli derived from mature embryos generally did not regenerate shoots, except for three Japanese varieties. The frequency of shoot regeneration from the calli derived from immature embryos was somewhat higher than that from those derived from mature embryos. Many of the Korean and Japanese varieties had a high shoot regenerating ability. However, few of the varieties from Ethiopia and Southwest Asia had a high shoot regenerating ability. No correlation was observed btween root regenerating ability and shoot regenerating ability of the varieties. No correlation was observed between callus proliferation and root regenerating ability between calli derived from mature and immature embryos. We could not find any difference in the shoot regenerating ability btween the two-rowed and six-rowed genotypes. No potential conflict of interest relevant to this article was reported.