林业科学2019，Vol.55Issue(3)：36-42,7.DOI:10.11707/j.1001-7488.20190304
旱柳枝条叶绿体光化学特征的径向异质性
Radical Heterogeneity of Photochemical Characteristics of Chloroplasts in Current-year Twigs of Salix matsudana
摘要
Abstract
[Objective]Stem photosynthesis plays an important role in growth, defense, reproduction and survival for woody plant, especially for deciduous trees. In this study, we investigate dradical heterogeneity and tissue specificity of chloroplast photochemical characteristics in branches, which can provide a basis for quantifying the contribution of different tissue to stem photosynthesis, and alsolay a foundation for revealing the adaptation mechanism of chloroplast to the heterogeneous light environment in twigs.[Methods]The CO2 release rates of current-year twigs of Salix matsudana clones were measured under light and dark conditions, and the contribution of stem photosynthesis to carbon recycle was evaluated. Besides, the photosynthetic pigment content, light absorption coefficient, photochemical efficiency and electron transport rate of bark, xylem and pith were determined, and the differences inphotochemical characteristics of chloroplasts between distinct tissues were analyzed. [Results]When exposed to the saturation light intensity, the stem photosynthesis rate of twig was 1.27 μmolCO2·m-2s-1, which was able to recover and fix 77％ of the carbon consumed by respiration. In the internal of twig, the total chlorophyll content of bark was highest, and was15.90 and 1.83 times higher than that of xylem and pith, respectively.The ratio of chlorophyll b to chlorophylla increased from bark to pith with the increase of radial depth. The carotenoid content and the ratio of carotenoid to chlorophyll in bark were significantly higher than those in xylem.The absorptivity coefficient of different tissues of the current-year-old branches significantly decreased along the radial direction.The maximum photochemical efficiency, effectively photochemical efficiency and relative electrontransport rate of PSII of bark were significantly higher than xylem and pith.[Conclusion]Stem photosynthesis in current-year-old twigs of Salix matsudana was able to recover and fix 77％ of the carbon consumed byrespiration. The photosynthetic pigment content and photochemical efficiency of chloroplasts decreased significantly with the increase of radial depth.Barkchlorenchyma was the major contributor to stem photosynthesis, and had a stronger capacity for quenching excess excitation energy. Xylem and pith chloroplasts maximized the limited light energy in the tissue by regulating the proportion of photosynthetic pigments.关键词
枝条光合/叶绿素/光化学效率/异质性Key words
stem photosynthesis/chlorophyll/photochemical efficiency/heterogeneity分类
农业科技引用本文复制引用
刘俊祥,于永畅,郎蓬蓬,孙振元..旱柳枝条叶绿体光化学特征的径向异质性[J].林业科学,2019,55(3):36-42,7.基金项目
中央级公益性科研院所基本科研业务费专项资金项目(RIF2013-04和CAFYBB2018SY003) （RIF2013-04和CAFYBB2018SY003）
国家自然科学基金青年科学基金项目(31600489) （31600489）
