Wang Xiaolin, Wu Tao, Asim Muhammad, Ling Aifen, Sun Yanguo, Shi Yi, Yan Huifeng
Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao, China.
Research and Development of Center, Liangshan Branch of Sichuan Tobacco Company, Xichang, China.
Front Plant Sci. 2023 Jul 13;14:1218076. doi: 10.3389/fpls.2023.1218076. eCollection 2023.
The difference between photosynthesis on the two leaf sides (dorsoventral asymmetry) of photosynthesis is important for light-use patterns, but the asymmetry is environment dependent. Its role in photosynthetic regulation has been intensively studied, but little is known about the impacts of direct and diffuse light on the asymmetry. Because of the current changing fraction of diffuse light in sky radiation, this study investigated the dorsoventral asymmetry of photosynthetic traits under direct and diffuse light conditions in an important food and energy crop, . A unique method was used to investigate the specific gas exchange of each leaf surface. Anatomical and morphological traits were different between the two surfaces of sorghum leaves, which might result in photosynthetic asymmetry. The variations in photosynthetic rates and stomatal conductance were significant between the two surfaces in direct and diffuse light, but the degree of dorsoventral asymmetry decreased in diffuse light. The integrated and of the adaxial illumination were significantly higher than that of abaxial illumination both in direct and diffuse light in sorghum leaves, but the of the integrated was 2.83 in direct light, while significantly dropped to 1.69 in diffuse light. Significant morphological differences between the two surfaces might cause photosynthetic asymmetry in the sorghum leaves. The variations of specific gas exchange were significant between direct and diffuse light, including in the incident and self-transmitted light. Compared with direct light, diffuse light reduced the stomatal sensitivity, with the degree of decline being greater in the adaxial surface, which caused weak dorsoventral asymmetry in photosynthesis. The specific photosynthetic characteristics in sorghum leaves varied obviously in direct and diffuse light, including in the incident and self-transmitted light, which contributed to the different overall gas exchange. Compared with direct light, the decline of stomatal sensitivity, which showed positive correlation with stomatal density, caused weakened dorsoventral asymmetry in photosynthesis in diffuse light. The findings provide new insights into dorsoventral asymmetry and the impact of diffuse light on photosynthesis in isobilateral leaves.
光合作用在叶片两侧（背腹不对称性）的差异对于光利用模式很重要，但这种不对称性取决于环境。其在光合调节中的作用已得到深入研究，但关于直射光和漫射光对这种不对称性的影响却知之甚少。由于当前天空辐射中漫射光比例不断变化，本研究调查了一种重要的粮食和能源作物在直射光和漫射光条件下光合特性的背腹不对称性。采用一种独特的方法来研究每片叶表面的特定气体交换。高粱叶片的两个表面在解剖学和形态学特征上存在差异，这可能导致光合不对称。在直射光和漫射光下，两个表面的光合速率和气孔导度变化显著，但在漫射光下背腹不对称程度降低。在高粱叶片中，无论是直射光还是漫射光，近轴面光照的光合有效辐射积分和光合有效辐射均显著高于远轴面光照，但直射光下光合有效辐射积分的光合有效辐射为2.83，而在漫射光下显著降至1.69。两个表面之间显著的形态差异可能导致高粱叶片的光合不对称。直射光和漫射光之间特定气体交换的变化显著，包括入射光和自透射光。与直射光相比，漫射光降低了气孔敏感性，近轴面下降程度更大，这导致光合作用中背腹不对称性减弱。高粱叶片在直射光和漫射光下，包括入射光和自透射光下，特定光合特性明显不同，这导致了不同的整体气体交换。与直射光相比，气孔敏感性的下降与气孔密度呈正相关，导致漫射光下光合作用中背腹不对称性减弱。这些发现为等面叶的背腹不对称性以及漫射光对光合作用的影响提供了新的见解。
