PDF(Pubmed)
Abstract：
The models used to describe the light response of electron transport rate in photosynthesis play a crucial role in determining two key parameters i.e., the maximum electron transport rate (J max) and the saturation light intensity (I sat). However, not all models accurately fit J-I curves, and determine the values of J max and I sat. Here, three models, namely the double exponential (DE) model, the non-rectangular hyperbolic (NRH) model, and a mechanistic model developed by one of the coauthors (Z-P Ye) and his coworkers (referred to as the mechanistic model), were compared in terms of their ability to fit J-I curves and estimate J max and I sat. Here, we apply these three models to a series of previously collected Chl a fluorescence data from seven photosynthetic organisms, grown under different conditions. Our results show that the mechanistic model performed well in describing the J-I curves, regardless of whether photoinhibition/dynamic down-regulation of photosystem II (PSII) occurs. Moreover, both J max and I sat estimated by this model are in very good agreement with the measured data. On the contrary, although the DE model simulates quite well the J-I curve for the species studied, it significantly overestimates both the J max of Amaranthus hypochondriacus and the I sat of Microcystis aeruginosa grown under NH4 +-N supply. More importantly, the light intensity required to achieve the potential maximum of J (J s) estimated by this model exceeds the unexpected high value of 105 μmol photons m-2 s-1 for Triticum aestivum and A. hypochondriacus. The NRH model fails to characterize the J-I curves with dynamic down-regulation/photoinhibition for Abies alba, Oryza sativa and M. aeruginosa. In addition, this model also significantly overestimates the values of J max for T. aestivum at 21% O2 and A. hypochondriacus grown under normal condition, and significantly underestimates the values of J max for M. aeruginosa grown under NO3 -N supply. Our study provides evidence that the \'mechanistic model\' is much more suitable than both the DE and NRH models in fitting the J-I curves and in estimating the photosynthetic parameters. This is a powerful tool for studying light harvesting properties and the dynamic down-regulation of PSII/photoinhibition.
摘要：
用于描述光合作用中电子传输速率的光响应的模型在确定两个关键参数中起着至关重要的作用，即最大电子传输速率(Jmax)和饱和光强(Isat)。然而,不是所有的模型都能准确拟合J-I曲线,并确定Jmax和Isat的值。这里,三个模型,即双指数(DE)模型，非矩形双曲(NRH)模型，以及由合著者之一（Z-PYe）及其同事开发的机械模型（称为机械模型），在拟合J-I曲线和估计Jmax和Isat的能力方面进行了比较。这里,我们将这三个模型应用于一系列先前收集的来自七个光合生物的Chla荧光数据，在不同的条件下生长。我们的结果表明，机械模型在描述J-I曲线方面表现良好，无论是否发生光系统II（PSII）的光抑制/动态下调。此外，该模型估计的Jmax和Isat与实测数据非常吻合。相反,尽管DE模型模拟了所研究物种的J-I曲线，它显着高估了在NH4-N供应下生长的A菜的Jmax和铜绿微囊藻的Isat。更重要的是,达到该模型估计的J（Js）的潜在最大值所需的光强度超过了小麦和A的105μmol光子m-2s-1的意外高值。NRH模型无法表征冷杉的动态下调/光抑制的J-I曲线，水稻和铜绿M.此外,该模型还显着高估了在21％O2下的T.aestivum和在正常条件下生长的A.a的Jmax值，并且大大低估了在NO3-N供应下生长的铜绿分枝杆菌的Jmax值。我们的研究提供了证据，表明“机械模型”在拟合J-I曲线和估算光合参数方面比DE和NRH模型都更合适。这是用于研究光捕获特性和PSII/光抑制的动态下调的强大工具。
