Western Region Agricultural Research Center

Lythrum anceps (Koehne) Makino (Japanese common name: "Misohagi") is an edible plant belonging to the Lythraceae family. It is mainly distributed in Asia, Northern Africa, and Europe. Plants of the genus Lythrum exhibit a broad range of biological activities including anti-inflammatory and antimicrobial activities. Because of this, the plants are used in traditional medicine to treat hemorrhage, infected wounds, and dysentery. The activation of peroxisome proliferator-activated receptor-gamma (PPARγ) is an effective target for improving insulin resistance and anti-inflammatory activity. However, PPARγ activation by the genus Lythrum remains unclear. Aiming to evaluate PPARγ activation by L. anceps, we generated a reporter cell line using an artificial chromosome vector that stably expresses dual-color beetle luciferases. Dual-color real-time bioluminescence monitoring revealed marked PPARγ activation in L. anceps extracts. Moreover, ellagic acid was identified as a PPARγ activator present in L. anceps by a bioassay-guided fractionation approach.

中山間地域の水田転換畑における多収栽培技術の確立は国内の農地の生産性向上において重要である．一方で，ダイズやムギ類では排水不良による湿害が問題となっている．これまでに中山間地域において，圃場造成時の切土箇所と盛土箇所で土壌水分量の傾向が異なっていることが示唆されており，平坦地よりも切土盛土による元地形からの変化量が相対的に大きい中山間地域においては，圃場造成履歴に着目することで多収に有効な排水対策を講じられる可能性がある．本研究は中山間地域における本暗渠未施工の水田転換畑を対象に，圃場内の排水不良を補助暗渠の利用により改善する技術の開発を目的として行った．試験は2020年から2022年に広島県東広島市の中山間地域において水田輪作を実施している農家圃場において行った．過去の航空写真を用いて当該圃場の切土盛土の分布地図を作成し，もみ殻暗渠施工機と弾丸暗渠施工機を使用して切土箇所と盛土箇所間の水の流れを改善する目的で，切土箇所と盛土箇所を接続する方向に補助暗渠の施工を行った．施工時に測量したところ，盛土箇所において地表面の沈降が見られ，盛土箇所に水が集まりやすいことが示唆された．2022年に，盛土箇所に深さ35 cmの排水口を設けた上で，補助暗渠を排水口から放射状に施工したところ，ダイズのm2当たり株数が向上し，全刈収量において有意な増収効果がみられた．これらの結果は，中山間地域においては，圃場の造成履歴に基づき排水口を検証し，盛土への集水を利用することで，排水対策の効果が高まることを示唆している．

Abstract In this study, we evaluated the effect of disinfecting agricultural materials contaminated with Pseudocercospora fuligena on tomato black leaf mold (BLM) using two methods: spraying with benzothiazole solution (referred to as "spraying") and smoking with Tetrachloroisophthalonitrile (TPN) smoke agent (referred to as "smoking"). Meta-analysis of the conidial germination data showed a combined relative risk (RR) of 0.20 (95% CI: 0.14–0.27) for spraying and 0.06 (95% CI: 0.04–0.08) for smoking, indicating significant inhibition of conidial germination. The effect of material disinfection using both methods on BLM occurrence were investigated in 14 greenhouses across four fields. In two experiments conducted in 2014, the survival period of tomato plants in the disinfected greenhouses was extended by 11 and 32 days using the spraying method and by 11 and 26.5 days using the smoking method (Kaplan–Meier) ,compared with ones in non-disinfected greenhouses. The general linear mixed model (GLMM) analysis of disease incidence data from tomato leaves during the late cultivation period from experiments in 2014, 2015, and 2021 revealed significant associations between disinfection and BLM occurrence. Subsequently, the meta-analysis results revealed an RR of 0.66 (95% CI: 0.63–0.70) in two experiments of spraying and an RR of 0.80 (95% CI: 0.74–0.87) in four experiments of smoking. In conclusion, disinfection of P. fuligena-contaminated agricultural materials effectively eliminated primary BLM infection and tended to slightly reduce disease occurrence during tomato cultivation. This study is the first to evaluate the impact of disinfecting conidia-contaminated materials on BLM occurrence in field experiments.

We aimed to determine the effects of maternal nutrient restriction (MNR) on the DNA methylation and gene expression patterns associated with metabolism and immunopoiesis in the thymuses of fetal Wagyu cattle. Pregnant cows were allocated to two groups: a low-nutrition (LN; 60% nutritional requirement; n = 5) and a high-nutrition (HN; 120% nutritional requirement, n = 6) group, until 8.5 months of gestation. Whole-genome bisulfite sequencing (WGBS) and RNA sequencing were used to analyze DNA methylation and gene expression, while capillary electrophoresis–Fourier transform mass spectrometry assessed the metabolome. WGBS identified 4566 hypomethylated and 4303 hypermethylated genes in the LN group, with the intergenic regions most frequently being methylated. Pathway analysis linked hypoDMGs to Ras signaling, while hyperDMGs were associated with Hippo signaling. RNA sequencing found 94 differentially expressed genes (66 upregulated, 28 downregulated) in the LN group. The upregulated genes were tied to metabolic pathways and oxidative phosphorylation; the downregulated genes were linked to natural killer cell cytotoxicity. Key overlapping genes (GRIA1, CACNA1D, SCL25A4) were involved in cAMP signaling. The metabolomic analysis indicated an altered amino acid metabolism in the MNR fetuses. These findings suggest that MNR affects DNA methylation, gene expression, and the amino acid metabolism, impacting immune system regulation during fetal thymus development in Wagyu cattle.

Meteorological data are essential components of decision-making systems for agriculture. Fine-resolution meteorological datasets are important where crops are grown in hilly areas with variable microclimates. A method for compiling daily surface air temperature (SAT) with 50 m resolution was previously developed. The compiled daily air temperature forecasts are available to farmers who produce Ujicha, tea via a web application. However, the complex terrain affects the accuracy of these forecasts. Our goal was to develop a practical system to provide hourly SAT data with 50 m resolution for a day-to-day decision-making system for agriculture. We applied two methods: a method for developing forecast models to forecast potential temperature differences between each grid and an observation site to compile 50 m resolution grid data; and a method for correcting SAT differences between the global spectral model output and observations (referred to as GSM_error). In both these methods, SAT was continuously forecast using the radiative cooling scale (RCS) computed near a public observation site. The RCS is a meteorological factor defined as the difference in potential temperature between an upper air pressure level and that at ground level. Forecast models for GSM_error were developed from observation data using a stepwise multiple regression (SMR), with geographic factors as independent variables in each group classified by the RCS. Statistical techniques were used for observation data to develop forecast models using machine learning, including lasso, ridge, random forest, support vector and deep neural network regression techniques. The SMR produced better forecast models for GSM_error than the other techniques. We found that SMR was better because it selected features relevant to GSM_error compared with machine learning, which fitted all features. Our grid data were compiled for hourly SAT with 50 m resolution and had a root mean square error of 1.67 °C.

Tailocins are headless phage tail structures that mediate interbacterial antagonism. Although the prototypical tailocins, R- and F-pyocins, in Pseudomonas aeruginosa, and other predominantly R-type tailocins have been studied, their presence in Alphaproteobacteria remains unexplored. Here, we report the first alphaproteobacterial F-type tailocin, named rhizoviticin, as a determinant of the biocontrol activity of Allorhizobium vitis VAR03-1 against crown gall. Rhizoviticin is encoded by a chimeric prophage genome, one providing transcriptional regulators and the other contributing to tail formation and cell lysis, but lacking head formation genes. The rhizoviticin genome retains a nearly intact early phage region containing an integrase remnant and replication-related genes critical for downstream gene transcription, suggesting an ongoing transition of this locus from a prophage to a tailocin-coding region. Rhizoviticin is responsible for the most antagonistic activity in VAR03-1 culture supernatant against pathogenic A. vitis strain, and rhizoviticin deficiency resulted in a significant reduction in the antitumorigenic activity in planta. We identified the rhizoviticin-coding locus in eight additional A. vitis strains from diverse geographical locations, highlighting a unique survival strategy of certain Rhizobiales bacteria in the rhizosphere. These findings advance our understanding of the evolutionary dynamics of tailocins and provide a scientific foundation for employing rhizoviticin-producing strains in plant disease control.

有機水稲作においては雑草防除に係る労力負担が非常に大きく，雑草害が主要な減収要因であることから省力・安定的な雑草防除技術の開発が求められている．本研究では，太陽光を動力としてGPSで水田内を無人航行する水田用自動抑草ロボット（以下，抑草ロボット）の雑草抑制効果および水稲収量への影響を2か年計 36地点の有機水稲圃場で検証した．抑草ロボットの導入により，生産者慣行の機械除草回数は平均で58％減少した．一方，抑草ロボット走行後の平均推定雑草乾物重は16.6 g m–2で，水稲の収量には影響しない程度の防除水準であった．抑草ロボットの防除効果は一年生雑草であるノビエやアゼナで高く，多年生雑草であるクログワイやオモダカで低くなる傾向であった．抑草ロボットの稼働期間が水稲移植直後から3週間程度であるため，発生期間が長い多年生雑草には効果が低く，多年生雑草の発生圃場では抑草ロボット引き上げ後に機械除草等の物理的な防除が必要であると考えられた．また，実証試験地の水稲平均収量は424 g m–2であり，生産者慣行と比較して平均10％の増収が確認された．以上より，抑草ロボットは除草労力を削減しつつ有機水稲作の収量を確保する新たな除草ツールとして有効であると考えられた．ただし，抑草ロボットが安定的に稼働するためには圃場水位を一定以上に保つ必要があり，圃場の均平化や用水の安定供給が導入条件として重要であった．今後は，抑草ロボットの雑草防除メカニズムや水稲収量の増加に寄与した要因を解析し，効果的な抑草ロボットの運用法や適用範囲の解明を目指す．

In general, either high or low branching may contribute to the yield potential of a cultivated crop. In this study, we evaluated the varietal differences in branching characteristics in asparagus crowns and examined the relationship between branching types and harvest characteristics among six varieties tested by careful observation. ‘UC 157’ developed numerous tillers and shoot apical meristems 6 months after sowing; thus, it was considered to be a high-branching type variety. In contrast, ‘All-male Gulliver’ and ‘Ryuryoku’ developed few tillers or shoot apical meristems and, were therefore considered to be low-branching type varieties. The final order of sympodial shoots and composition of sympodial shoots by order were similar between the varieties. ‘UC 157’ had fewer scale leaves attached to the underground shoots than other varieties, which may have been advantageous for developing underground shoots more rapidly. The total spear yield of ‘UC 157’ was high, but the marketable spear yield was similar to that of other varieties owing to the large number of thin spears. Although further studies are needed to determine whether high-branching or low-branching type asparagus varieties are more high-yielding, we determined that high-branching type varieties have lower labor productivity under unimproved growing conditions such as non-sparsely planted growing conditions.

Abstract Deep-water (DW) management in rice fields is a promising technique for efficient control of paddy weeds with reduced herbicide use. Maintaining a water depth of 10–20 cm for several weeks can largely suppress the weed growth, though it also inhibits rice growth because the DW management is usually initiated immediately after transplanting. Improving the DW resistance of rice during the initial growth stage is essential to avoid suppressing growth. In this study, we demonstrate a large genetic variation in the above-ground biomass (AGB) after the end of DW management among 165 temperate japonica varieties developed in Japan. Because the AGB closely correlated with plant length (PL) and tiller number (TN) at the early growth stage, we analyzed genomic regions associated with PL and TN by conducting a genome-wide association study. For PL, a major peak was detected on chromosome 3 (qPL3), which includes a gene encoding gibberellin biosynthesis, OsGA20ox1. The rice varieties with increased PL had a higher expression level of OsGA20ox1 as reported previously. For TN, a major peak was detected on chromosome 4 (qTN4), which includes NAL1 gene associated with leaf morphological development and panicle number. Although there was less difference in the expression level of NAL1 between genotypes, our findings suggest that an amino acid substitution in the exon region is responsible for the phenotypic changes. We also found that the rice varieties having alternative alleles of qPL3 and qTN4 showed significantly higher AGB than the varieties with the reference alleles. Our results suggest that OsGA20ox1 and NAL1 are promising genes for improving DW resistance in rice.

To promote the use of waxy barley bran, an underutilized resource, samples of waxy barley were divided into three parts: polished waxy barley powder (PWBP), inner bran layer powder (IBLP), and outer bran layer powder (OBLP). The color and appearance, general properties, minerals, vitamins, β-glucan, antioxidant properties, and aroma of each part were compared. In terms of appearance and color, IBLP and OBLP appeared more yellow than PWBP; general components that were more abundant in IBLP and OBLP compared with PWBP were protein, fat, and ash. IBLP and OBLP had characteristically high values of Mg and Zn, monounsaturated and polyunsaturated fatty acids, vitamin B1, total polyphenol content, H-ORAC, and DPPH. In particular, the vitamin B1 content of OBLP was approximately 10 times higher than that of PWBP, and Mg and Zn content was more than five times higher than in PWBP. The β-glucan content of IBLP and OBLP was lower than that of PWBP, but relatively high. GC-MS analysis revealed that hexanal was the aroma component common to all three samples, and the peak areas were in the order of PWBP > OBLP > IBLP.