Mechanistic Modeling Reveals Adaptive Photosynthetic Strategies of <i>Pontederia crassipes</i>: Implications for Aquatic Plant Physiology and Invasion Dynamics
The invasive aquatic macrophyte <i>Pontederia crassipes</i> (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 i...
Saved in:
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
|
| Series: | Biology |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2079-7737/14/6/600 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The invasive aquatic macrophyte <i>Pontederia crassipes</i> (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 <i>P. crassipes</i>. The Ye model provided superior accuracy (<i>R</i><sup>2</sup> > 0.996) in simulating the net photosynthetic rate (<i>P</i><sub>n</sub>) and electron transport rate (<i>J</i>), outperforming empirical models that overestimated <i>P</i><sub>nmax</sub> by 36–46% and <i>J</i><sub>max</sub> by 1.5–24.7% and failed to predict saturation light intensity. Mechanistic analysis revealed that <i>P. crassipes</i> maintains high photosynthetic efficiency in low light (<i>LUE</i><sub>max</sub> = 0.030 mol mol<sup>−1</sup> at 200 µmol photons m<sup>−2</sup> s<sup>−1</sup>) and robust photoprotection under strong light (<i>NPQ</i><sub>max</sub> = 1.375, PSII efficiency decline), supported by a large photosynthetic pigment pool (9.46 × 10<sup>16</sup> molecules m<sup>−2</sup>) and high eigen-absorption cross-section (1.91 × 10<sup>−21</sup> m<sup>2</sup>). 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 (<i>CE</i><sub>max</sub> = 0.085 mol m<sup>−2</sup> s<sup>−1</sup>) and water-use efficiency (<i>WUE</i><sub>i-max</sub> = 45.91 μmol mol<sup>−1</sup> and <i>WUE</i><sub>inst</sub> = 1.96 μmol mmol<sup>−1</sup>) highlighted its flexible energy management strategies. These results establish the Ye model as a reliable tool for characterizing aquatic photosynthesis and reveal how <i>P. crassipes</i> balances light harvesting and dissipation to thrive in fluctuating environments. These resulting insights have implications for both understanding invasiveness and managing eutrophic aquatic systems. |
|---|---|
| ISSN: | 2079-7737 |