令和5年度 研究成果

1. 第1四半期研究成果情報について

(1) 研究成果

1 Genetic architecture underlying proanthocyanidin composition in American hybrid grapes アメリカ系品種の果実におけるプロアントシアニジン組成の遺伝的構造

KOYAMA Kazuya, KONO Atsushi, BAN Yusuke, IWASHITA Kazuhiro, FUKUDA Hisashi, and GOTO-YAMAMOTO Nami

Background and goals
Grapes accumulate proanthocyanidins (PAs), complex polymer mixtures of flavan-3-ol units, in the skin and seeds. The composition of PAs, including subunit ratio and polymer length, and total concentration, is important because of their relationship to sensory properties of grape and wine. It is known that the grape species Vitis vinifera and Vitis labruscana have remarkably different PA concentration and composition. A mapping population derived from a cross between V.labruscana and V.vinifera was used to provide insight into the genetic architecture of PAs, as well as that of PA skin and seed properties.
Methods and key findings
The composition of PA subunits at the terminal and extension positions in the hybrid population’s skin and seeds was examined in great detail. Hierarchical clustering analysis of PA profiles grouped PA variables into five main clusters. There were distinct clusters related to compositional differences in skin and seeds, such as the percentage of galloylated or trihydroxylated subunits, polymer length, and the total PA concentration. A quantitative trait locus (QTL) analysis revealed several different minor loci between skin and seeds, each contributing to the phenotypic variation of total PA concentration. A few major QTLs on linkage groups 1 and 17 were discovered to contribute to the phenotypic variation of PA composition in both skin and seeds.
Conclusions and significance
A distinct genetic architecture between PA composition and total PA concentration in interspecific hybrid grapes was found. In contrast to PA concentration, a similar genetic architecture of PA composition was observed between skin and seeds.


American Journal of Enology and Viticulture, 74, 0740016 (2023)

2 Impact of storage conditions on the volatile aroma compounds of aged sake 貯蔵環境の熟成酒の香気成分への影響

BOERZHIJIN Surina, ISOGAI Atsuko, and MUKAI Nobuhiko

The current study reports the effect of storage length and temperature on the key aroma compounds of aged Japanese sake. In total, 41 bottles of commercial aged sake aged between 3 and 53 years, including 20 bottles of low-temperature (controlled at ≤ 15℃) aged sake and 21 bottles of ambient-temperature aged sake, were analyzed. The concentrations of sotolon, dimethyl trisulfide (DMTS) and 3-methylbutanal were greatly enhanced in ambient-temperature and peaked after 11–20 years of aging. While in low-temperature, the concentration of isoamyl acetate and ethyl caproate, the main compounds that contribute to the freshness of Japanese sake, were maintained above their odor thresholds (0.27 mg/L and 0.12 mg/L, respectively) in 3–30 years aging. Methional concentration decreased along with the aging time in ambient-temperature, while in low-temperature it increased up to 30 years of aging and declined afterwards. The results obtained in this study can be applied as a useful tool to regulate and optimize the aging methods of sake, furthermore, to predict the effects of storage time when applying different temperatures in the sake aging field.


Journal of Food Composition and Analysis, 121, 105351 (2023)

3 精米条件が酒造用原料米の酒造適性変化に及ぼす影響 ~扁平精米条件と通常精米条件の比較~ Changes in sake making properties of rice grains during the two ways of rice polishing

OKUDA Masaki, TAKAHASHI Kei, BAO Hong-Bin, KOHNO Hiromi, JOYO Midori, MUKAI Nobuhiko, KINOSHITA Yasuaki, ENOMOTO Yasuhiro, YOSHIOKA Toshiaki, IWAMOTO Osamu, EBI Katsuya, and TAMEHISA Hirobumi


The influences of rice polishing conditions on the rice properties for sake making were investigated. The rice grains were polished in the following two ways: a (#90 program) fine grind stone roll (#90), and a lower roll rotation speed and higher electric current, a (#60 program) usual grind stone (#60), and a normal roll rotation speed and normal electric current. The shapes of polished rice grains became flat in the #90 program, while grains remained close to the original, spherical shape in the #60 program. The ratios of cracked rice and residual embryos were higher in the #90 program than those in the #60 program. The rice protein content was lower in the #90 program than that in the #60 program. The contents of crude fat, Na, Mg, P and Ca decreased rapidly until rice polishing ratio of 80% in both programs, but the degree of decrease differed between the two programs. The contents of crude fat, Na, Mg, P and Ca were higher in the #90 program than that in the #60 program until the 70% polishing ratio. The water absorption ratio and the ratio of cracked rice during steeping at early stages were higher in the #90 program than that in the #60 program. The enzyme digestibility (Brix) was slightly higher in the #90 program than that in the #60 program; the contents of amino acids in digested solutions were lower and the contents of mineral contents in digested solutions were higher in the #90 program than in the #60 program. The data from the 70% polishing rice analyzed by the national standard methods of rice used for sake making correlated significantly with the data from various rice-polishing ratios. This result indicated that the data from 70% polishing rice analyzed by the national standard methods of rice used for sake making are useful to evaluate the rice properties, even in the case of a lower rice-polishing ratios.

日本醸造協会誌, 118(5), 340-364 (2023)

4 Targeted mutations produce divergent characteristics in pedigreed sake yeast strains 標的変異は、系統の明らかな清酒酵母菌株に様々な特性をもたらす


Modification of the genetic background and, in some cases, the introduction of targeted mutations can play a critical role in producing trait characteristics during the breeding of crops, livestock, and microorganisms. However, the question of how similar trait characteristics emerge when the same target mutation is introduced into different genetic backgrounds is unclear. In a previous study, we performed genome editing of AWA1, CAR1, MDE1, and FAS2 on the standard sake yeast strain Kyokai No. 7 to breed a sake yeast with multiple excellent brewing characteristics. By introducing the same targeted mutations into other pedigreed sake yeast strains, such as Kyokai strains No. 6, No. 9, and No. 10, we were able to create sake yeasts with the same excellent brewing characteristics. However, we found that other components of sake made by the genome-edited yeast strains did not change in the exact same way. For example, amino acid and isobutanol contents differed among the strain backgrounds. We also showed that changes in yeast cell morphology induced by the targeted mutations also differed depending on the strain backgrounds. The number of commonly changed morphological parameters was limited. Thus, divergent characteristics were produced by the targeted mutations in pedigreed sake yeast strains, suggesting a breeding strategy to generate a variety of sake yeasts with excellent brewing characteristics.


Microorganisms, 11(5), 1274 (2023)