記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Physiologia Plantarum  

Tracer injection has long been recognized as a valuable tool for delineating tree hydraulics and assessing water transport pathways. Recently, isotope tracers have emerged as innovative instruments for investigating tree hydraulics, providing new insights into tree water dynamics. Nevertheless, there is a critical need for further research to comprehensively grasp water movement and distribution within trees. A previously introduced technique for analyzing the isotopic ratio of water in wet tissues, offering millimeter-scale resolution for visualizing tracer movement, faces challenges due to its underdeveloped sample preparation techniques. In this study, we introduced an H218O tracer into S. gracilistyla samples, exclusively comprising indeterminate roots, stems, and leaves, cultivated through hydroponics and grown within the current year. Our objective was to assess the axial distribution of the tracer in the xylem. Additionally, we devised a novel method for preparing frozen wet tissue samples, enhancing the repeatability and success rate of experiments. The results demonstrated that all frozen wet tissue samples exhibited an average water loss rate of less than 0.6%. Isotopic analysis of these samples unveiled a consistent decline in tracer concentration with increasing height in all Salix specimens, with three out of five samples revealing a significant isotope gradient. Our findings affirm the efficacy and practicality of combining isotopic labeling with freezing, stabilization, and preparation techniques. Looking ahead, our isotopic labeling and analysis methods are poised to transcend woody plants, finding extensive applications in plant physiology and ecohydrology.

DOI： 10.1111/ppl.14292

Scopus

PubMed

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Annals of Forest Science  

Key message: We elucidated the age trends of narrow-sense heritability and phenotypic/genetic correlations and the age–age genetic correlation of growth ring components of Cryptomeria japonica D. Don by investigating progenies of controlled crossings by soft X-ray densitometry analysis. Wood density in the C. japonica breeding program can be efficiently improved by selecting trees with a higher earlywood density and latewood percentage as early as forest stand ages of 5–9 years. Context: Wood density within the trunk is affected by the intra-ring wood density profile and its age trend from pith to bark. Wood density can be efficiently improved by clarifying whether wood density and highly correlated intra-ring components are under additive genetic control. Aims: The aim of this study was to elucidate the age trends of narrow-sense heritability and phenotypic/genetic correlations of growth ring components and investigate the possibility of early selection for improving wood density in Cryptomeria japonica. Methods: We quantified seven growth ring components (width, density, earlywood/latewood width, average earlywood/latewood density, and latewood percentage) for 5112 annual rings of 342 18-year-old trees derived from 24 controlled pollinated full-sib families of C. japonica plus tree clones by soft X-ray densitometry analysis. Genetic parameters and correlations among the seven growth ring components were analyzed using a linear mixed model and the breedR package. Results: Earlywood density and latewood percentage exhibited a higher phenotypic and genetic correlation with ring density than the other ring components at almost all ages. Earlywood density and latewood percentage exhibited a lower correlation with ring width than the other ring components after a stand age of 5 years. The age–age genetic correlation of earlywood density and latewood percentage was 0.70 for a stand age of 17 years and was strong at stand ages of 5 and 9 years. Conclusion: Efforts focusing on improving earlywood density and latewood percentage may contribute to improving wood density efficiently in tree breeding programs for C. japonica. Traits related to the ring density of C. japonica trees can possibly be selected as early as stand ages of 5–9 years, and the required period for progeny selection may be substantially shortened when selecting trees with high wood density.

DOI： 10.1186/s13595-023-01212-9

Scopus

その他リンク： https://link.springer.com/article/10.1186/s13595-023-01212-9/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Tree Physiology  

The dye injection method has been applied to many species to analyze the xylem water transport pathway in trees. However, traditional dye injection methods introduced dye tracers from the surface of cut stems, including several annual rings. Furthermore, the traditional dye injection method did not evaluate radial water movement from the outermost annual rings to the inner annual rings. In this study, we assessed the difference in radial water movement visualized by an injected dye, between stem base cut and current-year root cut samples of Salix gracilistyla Miq., with current-year roots grown hydroponically. The results showed that the number of stained annual rings in the root cut samples was smaller than that in the stem cut samples, and the percentage of stained vessels in the root cut samples was significantly smaller than that in the stem base cut samples in the second and third annual rings. In the current-year root cut samples, water transport mainly occurred in the outermost rings from the current-year roots to leaves. In addition, the theoretical hydraulic conductivity of stained vessels in the stem cut samples was higher in the current-year root cut samples in the second and third annual rings. These findings indicate that the previously reported dye injection method using stem cut samples overestimated the water transport pathway in the inner part of the stems. Moreover, previous hydraulic conductivity measurement methods might not have considered the effects of radial resistance through the annual ring boundary, and they might have overestimated the hydraulic conductivity in the inner annual rings.

DOI： 10.1093/treephys/tpad056

Scopus

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media SA  

Compared to trees, little is known about the respiratory characteristics of bamboo, especially culm respiration. In this study, we measured the respiration rates of current year, 2, 3, and above 4-year-old Moso bamboo (Phyllostachys pubescens) culms and examined its relation to culm morphology and anatomical structure. Current year culms had substantially higher respiration rates (1.9 ± 0.46 μmol m^–2 s^–1) compared to older culms (2, 3, and above 4-year-old average: 0.17 ± 0.09 μmol m^–2 s^–1). Culm wood density increased with age, with the concurrent thickening of parenchyma cell walls in the culm tissue. Nitrogen content in the culm tissue decreased with culm age. Both culm wood density and nitrogen content had significant relationships with culm respiration rate. On the other hand, culm height, wall thickness, and circumference did not affect culm respiration rate. Although bamboo culms did not change in size through the year, anatomical changes in the culm tissue that accompanied the aging of a culm affected the respiration. The culm age would have a significant effect on the evaluation of the respiratory characteristics of the bamboo forest. Our results suggested that young culms required a large amount of respiration to grow “inward” as cell wall thickening and also to maintain the relatively large amount of active tissue.

DOI： 10.3389/ffgc.2022.868732

Web of Science

記述言語：日本語   掲載種別：記事・総説・解説・論説等（大学・研究所紀要）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：記事・総説・解説・論説等（その他）  

開催年月日： 2022年5月

記述言語：英語  

長い年月を要する林木育種において交配設計の最適化や次世代候補木の選抜などの効率化を進めるため、個体の遺伝子型を用いて形質を予測する技術の開発を進めてきた。これまでに茨城県日立市の育種集団林一ヵ所の精英樹F₁集団576個体の遺伝子型を決定し、計15の成長・材質関連形質のゲノミック予測モデルを構築している。これらの形質のゲノミック予測モデルの予測精度に影響を与える要因を明らかにするため、本研究では集団内の遺伝的構造を考慮して集団をサブグループに分けてモデル作成を行うとともに、モデルの予測精度に対する形質分散の影響を調べた。その結果、形質によっては全個体を対象としたモデルよりも特定のサブグループを対象としたモデルでの予測精度の方が高い場合が見られた。また、サブグループ間のゲノミック予測モデルの精度の差異と形質分散の関係を解析したところ、10の形質でサブグループ内の形質分散が小さい場合にモデルの予測精度が低い傾向が認められた。これらの知見はゲノミック予測を行う際に集団内の遺伝的構造と形質分散を考慮する必要があることを示唆している。

開催年月日： 2021年3月

記述言語：日本語   会議種別：ポスター発表  

記述言語：日本語   会議種別：ポスター発表  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：ポスター発表