Hokkaido Agricultural Research Center

Abstract In 2013 QoI-resistant isolates of the rice blast fungus (MoO) emerged suddenly and spread in Hyogo Prefecture. To estimate factors associated with their spread and subsequent survival, the population structure of MoO isolates was monitored from 2013 through 2023 using DNA fingerprinting with Pot2 . Most of the QoI-resistant isolates collected in 2013 were classified into haplotype HY1, irrespective of areas of collection in Hyogo Prefecture. This result suggests that the sudden emergence and spread of the QoI-resistant isolates in 2013 were caused by almost the single haplotype HY1 probably through seed transmission. After discontinuance of the QoI fungicide application in 2014, however, the QoI-resistant isolates decreased over the course of several years, suggesting that genetic alternations conferring the QoI resistance may have caused a decrease in fitness. Conversely, QoI-sensitive isolates increased after 2015, but predominant haplotypes changed across years of collection. We suggest that it could be possible to re-use the QoI-fungicide if the disappearance of the resistant strains is confirmed by careful monitoring of QoI resistance throughout the prefecture, especially in and around fields for seed production.

Abstract A 333‐day‐old Holstein cow from a breeding farm in Hokkaido, Japan, exhibited lameness in the left hindlimb, which was caused by osteomyelitis. Despite systemic administration of antibiotics for 15 days, the cow continued to demonstrate lameness. However, gait had improved after 5 days of starting treatment with antibiotics, nonsteroidal anti‐inflammatory drugs and platelet‐rich plasma via regional limb perfusion. Treatment was discontinued after 26 days from the start of regional limb perfusion because the condition was treated. This case report demonstrates that systemic antibiotics were poorly effective, but local administration via regional limb perfusion and antibiotics, nonsteroidal anti‐inflammatory drugs and platelet‐rich plasma combination could accelerate the healing process of osteomyelitis in cattle.

Alterations in pest ecology due to climate change can affect crop production. Understanding the rate and period of pest development is essential for predicting population dynamics and determining the optimal timing for pesticide application to ensure stable crop production. In this study, we aimed to develop a mechanical method for determining the developmental periods of rice planthoppers and evaluate the impact of climate change on these periods over a 42-year period. We evaluated interannual variations in the developmental periods of two rice pests, Nilaparvata lugens (Stål) and Sogatella furcifera (Horváth), using light traps to capture data between 1980 and 2022 from 20 areas in Kyushu, Japan, a region of East Asia severely affected by rice planthopper outbreaks. Meteorological data revealed a trend of increasing daily mean temperature (2.2-4.5 × 10-2 °C year-1). A significant correlation was also detected between the length of developmental period and temperature (P < 0.001). For both N. lugens and S. furcifera, a significant trend toward progressively shorter developmental periods was observed over time, even after accounting for differences in the starting dates of development (P < 0.01). These results indicate that for pests, developmental periods have been progressively shortening in response to warming associated with climate change. This study provides important insights for predicting future pest ecology under climate change conditions based on results obtained from rearing experiments conducted in laboratory. © 2026 Society of Chemical Industry.

Understanding the long-term dynamics of radiocesium (137Cs) in forests contaminated by the Fukushima nuclear accident requires determining when these dynamics reach a quasi-equilibrium state, in which the flux of 137Cs between soil and trees becomes approximately balanced. In this study, we analyzed time-series variations from 2011 to 2020 in the total 137Cs inventory and 137Cs distribution in aboveground compartments (needles/leaves, branches, bark, sapwood, and heartwood). Time-series analysis using a dynamic linear model indicated that the decay-corrected total 137Cs inventory (as of September 1, 2020) and its distribution in the aboveground compartments remained stable from 2017 onward, suggesting that a quasi-equilibrium state had been reached. Given this stability in both inventory and distribution, the aggregated transfer factor (Tag)—defined as the 137Cs activity concentration in aboveground tree tissues divided by the total 137Cs inventory in soil—measured approximately 6 years after the Fukushima nuclear accident can be considered representative of the long-term transfer of 137Cs from forest soil to trees. These findings on the stability of 137Cs in forests provide valuable insights for validating the accuracy of models that predict long-term 137Cs activity concentration in stem wood.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-34898-0.

Salmonella enterica serovar Senftenberg (S. Senftenberg) is one of the most prevalent Salmonella serovars and can be isolated from various animals and humans. According to the White-Kauffmann-Le Minor (WKL) scheme, the antigenic formula of S. Senftenberg is defined as 1,3,19:g,[s],t:-. Although the antigenic formula 1,3,19:z27:- was formerly designated as serovar Simsbury, this name was later removed from the WKL scheme due to reports of interconvertibility between serovars Senftenberg and Simsbury. The H:z27 antigen is currently recognized as one of the R-phase H antigens of S. Senftenberg. To elucidate the genetic basis of H:z27 antigen expression in S. Senftenberg, we determined the whole-genome sequences of isolates expressing the H:z27 antigen. These isolates belonged to sequence type (ST) 185 and harbored a horizontally acquired chromosomal region containing the fljA, fljB, and pinR genes, which are predicted to encode a translational repressor of fliC mRNA, a phase 2 flagellin, and an invertase, respectively. A deletion mutant lacking this region expressed the H:g,s,t antigen instead of H:z27, as confirmed by serotyping and Western blot analysis. Phylogenetic analysis based on S. Senftenberg genome archives, together with the sequences obtained in this study, suggested that the S. Senftenberg ST185 lineage acquired the fljAB-pinR locus around 1867. In contrast, our broader phylogenetic analysis of Salmonella serovars indicated that S. Senftenberg ST14 is genetically closer to certain other serovars than to ST185, while ST185 shows a closer relationship to a different serovar than to ST14. These findings suggest that S. Senftenberg comprises at least two distinct genomic lineages.

Cancer in dogs remains a major challenge in modern veterinary medicine. Immunotherapyusing immune checkpoint inhibitors (ICIs) is available for various human tumor types, andrecent veterinary clinical studies have shown that ICIs are a promising approach fortreating canine cancers. A canine chimeric anti-PD-L1 antibody, c4G12 (HFC-L1), has beeninvestigated for canine cancer immunotherapy; however, its clinical benefits have not beenwell characterized in tumors other than pulmonary metastatic (stage IV) oral malignantmelanoma (OMM). To explore the efficacy and safety of HFC-L1, we conducted a clinicalstudy in dogs with stage I–III OMM or other tumor types (n=12). HFC-L1treatment at a dose of 5 mg/kg every 2 weeks was well tolerated, and no grade 3 or highertreatment-related adverse events were reported. Among the dogs eligible for responseevaluation (n=10), a partial response was observed in one dog withsquamous cell carcinoma, resulting in an objective response rate of 10%. In addition, in adog with ceruminous cell carcinoma, clinical evidence of a tumor response was observed inmetastatic lung lesions. Together, these results suggest that the HFC-L1 therapy isapplicable for the treatment of various tumor types, although its clinical benefits shouldbe further evaluated in clinical studies involving a larger number of dogs with each tumortype.

Immunoglobulins in ruminant mammary secretions play a central role in active immune protection of the mammary gland against infections. Ig are present in both colostrum and milk from cows, and interest in routinely quantifying the Ig content in milk for herd management and genetic improvement of disease resistance is increasing. Therefore, the objective of this study was to develop a prediction equation for Ig (IgA, IgG, and IgM) concentrations in milk from Holstein cows using milk Fourier-transform infrared (FTIR) spectral data and to evaluate the practical feasibility of the predicted Ig concentration in milk. First, we developed prediction equations for Ig concentrations in milk using 1,633 milk samples comprising both Ig concentrations in milk and milk FTIR spectral data. We then evaluated the predictive accuracy of the developed equations using 3 different factors: derivative preprocessing, spectral wavenumber ranges, and regression models. Our results demonstrated that the prediction equations based on the partial least squares regression and 4 machine learning regression models exhibited the highest predictive accuracy for all traits under the conditions of nonderivative preprocessing and spectral wavenumber range related to milk quality traits. Their predictive accuracies were moderate, with the R2 ranging from 0.41 to 0.42, 0.50 to 0.52, and 0.38 to 0.39 for IgA, IgG, and IgM, respectively. Second, we evaluated the practical applicability of the predicted Ig concentration by comparing the trends of both the observed and predicted Ig concentrations with respect to several environmental effects. A linear model was applied using the observed and predicted Ig concentrations, and the LSM of the levels for each environmental effect (lactation stage, SCS, parity, and milk yield) was estimated. Our results showed that the estimated environmental effects of the observed and predicted values showed similar trends for all traits. These results indicate that it is possible to estimate environmental effects using the predicted values obtained via the prediction equation with moderate accuracy. Although the predictive accuracy obtained here may be effective for estimating effects at the herd level, further improvement in predictive accuracy is necessary for estimating effects at the cow level.

Buckwheat (Fagopyrum esculentum) is a heterostylous self-incompatible crop that requires outcrossing for seed formation. Pollen parents influence the traits of seeds in many plants, but their influence in buckwheat is unknown. Here, we crossed self-incompatible (SI) and self-compatible (SC) lines with different rutin contents. The average rutin contents of SI leading cultivars were all 0.15–0.21 mg/g, and a SI high rutin content line that we had developed was 0.6 mg/g, although it has wide range SDs (0.12–0.41). On the other hand, the average rutin contents of SC lines were 0.01–0.06 mg/g, with stable SDs (0.02–0.03). In crosses between high- and low-rutin parents, the average rutin content of F1 seeds was significantly lower than that of the high-rutin parent and higher than that of the low-rutin parent, indicating that the pollen parent influences the rutin content in seeds of buckwheat. RNA-seq analysis confirmed that alleles of several genes encoding enzymes involved in rutin synthesis derived from pollen parents were expressed during seed formation.

SummaryEclepins are root‐secreted compounds that induce the hatching of cyst nematodes. Solanoeclepin A (SEA) and B (SEB) have been isolated as potent hatching factors for potato cyst nematodes (PCNs). SEB is biosynthesized in roots, released into the rhizosphere, and converted into SEA by soil microorganisms. However, given that SEB and SEA exhibit comparable hatching‐inducing activity toward PCNs, the ecological significance of microbial solanoeclepin metabolism in eclepin‐mediated communication remains unclear.In this study, we identified solanoeclepin C (SEC), a previously unrecognized solanoeclepin secreted by tomato and potato roots. Structural analysis revealed that SEC is an acetylated derivative of SEB. Soil incubation experiments demonstrated that SEC is converted into SEB and subsequently into SEA. SEC exhibits 10 000‐fold lower hatching‐inducing activity than SEA.Gene expression analysis in hydroponically grown tomatoes showed that solanoeclepin biosynthesis is upregulated under nitrogen and phosphorus deficiencies, with nitrogen starvation having the strongest effect.Our results demonstrate that although SEC itself exhibits low hatching‐inducing activity, it is converted by soil microorganisms into SEB and SEA, which are then exploited by PCNs to trigger their hatching. These findings reveal a previously unrecognized three‐way interaction among plants, soil microbes, and nematodes mediated by solanoeclepins.

ホルスタイン種牛の代謝に関する指標形質として乳中β-ヒドロキシ酪酸および由来別脂肪酸組成に着目し，泌乳初期の指標形質と生産（305日乳量，乳脂量およびタンパク質量），繁殖（初回授精日数，空胎日数，初回授精受胎率），健康（乳期内の最大体細胞数）および長命性（生存能力，在群性）形質間の表型および遺伝的関連を調査した．生産形質等を従属変数，指標形質クラスを説明変数とする最小二乗分析から，指標形質の改善に伴い生産形質は減退しそれ以外の形質は向上する傾向にあった．多形質モデルによる遺伝分析から，指標形質の遺伝率は概ね0.2から0.3の範囲と推定された．推定された遺伝相関から，指標形質に対する選抜は生産形質に好ましくない相関反応，繁殖および健康形質に好ましい相関反応をもたらすと示唆された．指標形質による選抜は可能であるが，実用上は生産形質との拮抗関係も考慮する必要がある．