Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, 266101, People's Republic of China.
Institute of Agricultural Resources and Regional Planning of Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China.
J Plant Res. 2020 Jan;133(1):35-48. doi: 10.1007/s10265-019-01151-5. Epub 2019 Nov 19.
Plants can change leaf forms, adjusting light conditions on their adaxial and abaxial surfaces, to adapt to light environments and enhance their light use efficiencies. The difference between photosynthesis on the two leaf sides (dorsoventral asymmetry) is an important factor that affects light use efficiency. However, photosynthetic dorsoventral asymmetry is rarely compared under direct and diffuse light conditions. To estimate the impacts of recently reported alterations in direct and diffuse light in the sky radiation on plant carbon assimilation, variations in morphology between the two leaf sides in tobacco (Nicotiana tabacum L.) were investigated, and the dorsoventral responses of photosynthesis to illuminating directions were compared in direct and diffuse light. Dorsoventral asymmetry was reflected in stomatal densities, anatomic structures, and photochemical traits, which caused markedly different photosynthetic rates as well as stomatal conductances both in direct and diffuse light. However, the degree of photosynthetic asymmetry was weakened in diffuse light. The diffuse light caused a greater stomatal conductance on the abaxial side than direct light, which resulted in reduced photosynthetic asymmetry. In addition, the photosynthetic dorsoventral asymmetry could be affected by the photosynthetic photon flux density. These results contribute to understanding the dorsoventral regulation of photosynthesis in bifacial leaves, and provide a reference for breeding to cope with the increase in the proportion of diffuse light in the future.
植物可以改变叶片形态，调节其腹背两面的光照条件，以适应光照环境并提高其光能利用效率。两面光合作用的差异（背腹不对称性）是影响光能利用效率的一个重要因素。然而，在直射光和散射光条件下，很少比较光合作用的背腹不对称性。为了估计天空辐射中直射光和散射光最近报道的变化对植物碳同化的影响，研究了烟草（Nicotiana tabacum L.）两面形态的变化，并在直射光和散射光下比较了光合作用对光照方向的背腹响应。气孔密度、解剖结构和光化学特性反映了背腹不对称性，这导致了在直射光和散射光下光合作用速率以及气孔导度都有明显的不同。然而，在散射光下，光合作用的不对称性程度减弱。散射光在叶片背面引起的气孔导度大于直射光，从而降低了光合作用的不对称性。此外，光合作用的背腹不对称性可能受到光合光子通量密度的影响。这些结果有助于理解双面叶光合作用的背腹调节，并为未来应对散射光比例增加的育种提供参考。
