岡山大学農学部 Acta Medica Okayama 2186-7755 113 2024 水稲における窒素利用効率の品種間差異 17 24 EN Kuniyuki Saitoh The Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Yoshifumi Iwame The Graduate School of Natural Science and Technology, Okayama University Masahiko Maekawa Institute of Plant Science and Resources （IPSR）, Okayama University Kazuyoshi Takeda Institute of Plant Science and Resources（IPSR）, Okayama University We investigated the effects of fertilizer-free and fertilizer-applied cultivation on growth, yield and nitrogen (N) utilization of rice cultivars in our Kurashiki paddy fields (Institute of Plant Science and Resources, Okayama Univ.), which have been cultivated without fertilizer since 1970, and also in our Okayama paddy fields, which are conventionally cultivated. In 2001, the cultivars Nipponbare (NIP) and Nourin 18 (N18) were cultivated in the Kurashiki fields, with a “0N plot” (no fertilizer application), a “1N plot” (standard fertilizer application), and a “2N plot” (double fertilizer application). In 2002, five cultivars were grown without fertilizer in the Kurashiki fields, and 51cultivars were tested in 0N and 1N plots in the Okayama fields. Yield (2001) in the Kurashiki fields was higher in the 0N plot for N18 (379g m–2), which had a higher number of spikelets per m2, than NIP (300 g m–2), while in the 1N and 2N plots it was higher for NIP, which had a higher percentage of ripening, and N18 had high yield potential even without fertilizer application, but low fertilizer tolerance. The differences in yield were related to N-uptake (NU), and the differences in N use efficiency (NUE, yield/NU) between cultivars were small. The pot experiment showed that the yield of 0N plot was higher for N18 than NIP grown in Kurashiki soil because of the higher number of spikelets per hill, and the yield in the Okayama soil was higher than that in the Kurashiki soil. Long-term non-fertilized soils are of poor soil fertility, which also decreases the NUE, and the NUE of N18 is higher than that of NIP under isolated conditions. The difference in yields is closely related to sink capacity (SC). In 2002, yields in the Kurashiki fields were highest in Takanari (TAK, 494g m–2) and lowest in NIP (350g m–2), and differences in yields were closely related to SC. NUE was highest in TAK (68.6) and lowest in Akebono (48.1). TAK had high NUE and high sink production efficiency (SPE, SC/NU), while N18 had low NUE but high SC due to higher NU, ensuring high yield even under unfertilized cultivation. Yields in the 0N and 1N plots cultivated in 2002 varied between 244–631g m–2 and 199–769g m–2, respectively. A close positive correlation was observed between yield and SC, and between NU and SC, suggesting that the SC through NU is involved in determining yield. A positive correlation was also observed between NUE and yield. It was found that yield increased with an increase in NUE, and that NUE decreased although yield increased with fertilizer application. Through selection of cultivars with high SPE, it is expected that it will be possible to breed low-input, high-yielding cultivars with high NUE in the future. No potential conflict of interest relevant to this article was reported.

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.

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.