Liu Lihua, Yang Xiaolong, Robakowski Piotr, Ye Zipiao, Wang Fubiao, Zhou Shuangxi
College of Safety Engineering and Emergency Management, Nantong Institute of Technology, Nantong 226002, China.
School of Life Sciences, Nantong University, Nantong 226019, China.
Biology (Basel). 2025 May 25;14(6):600. doi: 10.3390/biology14060600.
The invasive aquatic macrophyte (water hyacinth) exhibits exceptional adaptability across a wide range of light environments, yet the mechanistic basis of its photosynthetic plasticity under both high- and low-light stress remains poorly resolved. This study integrated chlorophyll fluorescence and gas-exchange analyses to evaluate three photosynthetic models-rectangular hyperbola (RH), non-rectangular hyperbola (NRH), and the Ye mechanistic model-in capturing light-response dynamics in . The Ye model provided superior accuracy ( > 0.996) in simulating the net photosynthetic rate () and electron transport rate (), outperforming empirical models that overestimated by 36-46% and by 1.5-24.7% and failed to predict saturation light intensity. Mechanistic analysis revealed that maintains high photosynthetic efficiency in low light ( = 0.030 mol mol at 200 µmol photons m s) and robust photoprotection under strong light ( = 1.375, PSII efficiency decline), supported by a large photosynthetic pigment pool (9.46 × 10 molecules m) and high eigen-absorption cross-section (1.91 × 10 m). Unlike terrestrial plants, its floating leaves experience enhanced irradiance due to water-surface reflection and are decoupled from water limitation via submerged root uptake, enabling flexible stomatal and energy regulation. Distinct thresholds for carboxylation efficiency ( = 0.085 mol m s) and water-use efficiency ( = 45.91 μmol mol and = 1.96 μmol mmol) highlighted its flexible energy management strategies. These results establish the Ye model as a reliable tool for characterizing aquatic photosynthesis and reveal how balances light harvesting and dissipation to thrive in fluctuating environments. These resulting insights have implications for both understanding invasiveness and managing eutrophic aquatic systems.
入侵性水生大型植物（凤眼莲）在广泛的光照环境中表现出非凡的适应性，然而其在高光和低光胁迫下光合可塑性的机制基础仍未得到很好的解决。本研究结合叶绿素荧光和气体交换分析，评估了三种光合模型——直角双曲线（RH）、非直角双曲线（NRH）和叶机理模型——以捕捉凤眼莲的光响应动态。叶模型在模拟净光合速率（Pn）和电子传递速率（ETR）方面提供了更高的准确性（R²>0.996），优于经验模型，经验模型高估Pn 36 - 46%，高估ETR 1.5 - 24.7%，且未能预测饱和光强。机理分析表明，凤眼莲在低光下保持高光合效率（200 μmol光子·m⁻²·s⁻¹时α = 0.030 mol CO₂·mol⁻¹），在强光下具有强大的光保护能力（NPQ = 1.375，PSII效率下降），这得益于大量的光合色素库（9.46×10⁻⁶分子·m⁻²）和高特征吸收截面（1.91×10⁻²⁰ m²）。与陆生植物不同，其浮叶因水面反射而光照增强，通过水下根系吸收与水分限制解耦，从而实现灵活的气孔和能量调节。羧化效率（CE = 0.085 mol CO₂·m⁻²·s⁻¹）和水分利用效率（WUE = 45.91 μmol CO₂·mol⁻¹和LUE = 1.96 μmol CO₂·mmol⁻¹）的不同阈值突出了其灵活的能量管理策略。这些结果确立了叶模型作为表征水生光合作用的可靠工具，并揭示了凤眼莲如何平衡光捕获和光耗散以在波动环境中茁壮成长。这些结果对于理解入侵性和管理富营养化水生系统都具有重要意义。
