光系统II实际光化学量子效率对光的响应模型的比较

doi:10.17521/cjpe.2015.0470

摘要/Abstract

摘要：

为了比较光系统II实际光化学量子效率(Φ_PSII)对光的响应机理模型(简称机理模型)、负指数模型和指数模型的优缺点, 用LI-6400-40B光合作用测定仪控制CO₂浓度和温度, 测量了剑叶金鸡菊(Coreopsis lanceolata)、黄荆(Vitex negundo)和大狼杷草(Bidens frondosa)的电子传递速率(ETR)对光的响应曲线(ETR-I)和Φ_PSII对光的响应曲线(Φ_PSII-I), 然后用这3个模型分别拟合了这些数据。拟合结果表明: 3个模型都可以较好地拟合这3种植物的ETR-I的响应数据和Φ_PSII-I的响应数据, 但由指数模型拟合ETR-I和Φ_PSII-I的响应数据得到相应的饱和光强(PAR_sat)和光系统II最大光能利用效率(F_v/F_m)之间存在显著差异, 且估算的饱和光强远低于实测值。由机理模型可知, Φ_PSII不仅与光强的函数有关, 还与植物的内禀特性有关, 即与天线色素分子的本征光能吸收截面、激子的传递效率、能级的简并度、光化学反应常数、热耗散常数和处于最低激发态的平均寿命等参数有关。此外, 由机理模型还可知, Φ_PSII随光强的增加而下降的原因是捕光色素分子的有效光能吸收截面随光强增加而降低。

关键词: 光系统II, 实际光化学量子效率, 电子传递速率, 机理模型, 天线色素分子

Abstract:

Aims The objective of this study was to compare the merits and demerits of three models (i.e., a mechanistic model, a negative exponential model and an exponential model) to simulate the light-response curves of actual photochemical efficiency (Φ_PSII-I). Moreover, it was to reveal the mechanism that Φ_PSII decreased with light intensity increasing.
Methods The electron transport rate (ETR) and the Φ_PSII of Coreopsis lanceolata, Vitex negundo and Bidens frondosa were measured by LI-6400-40B under controlled CO₂concentrations and temperatures, then light-response curves of ETR-I and Φ_PSII-I were simulated by a mechanistic model, a negative exponential model and an exponential model, respectively.
Important findings The fitted results showed that ETR-I and Φ_PSII-I data of the three plants fit well to the three models. However, the saturation light intensity (PAR_sat) and maximum efficiency of photosystem II (F_v/F_m) estimated by exponential model for ETR-I and Φ_PSII-I were greatly different from the measured data. Moreover, the mechanistic model revealed that the Φ_PSII for the three species decreased with increasing I as the effective light energy absorption cross-section of light-harvesting pigments decreased. At the same time, it showed that Φ_PSII depended not only on I, but also on eigen-absorption cross-section of light-harvesting pigment, efficiency of exciton, photochemical constant, heat dissipation constant and average lifetime of light-harvesting pigment-protein complex in the lowest state.

Key words: photosystem II, actual photochemical efficiency, electron transport rate, a mechanistic model, light- harvesting pigment-protein complex

叶子飘, 胡文海, 闫小红. 光系统II实际光化学量子效率对光的响应模型的比较. 植物生态学报, 2016, 40(11): 1208-1217. DOI: 10.17521/cjpe.2015.0470

Zi-Piao YE, Wen-Hai HU, Xiao-Hong YAN. Comparison on light-response models of actual photochemical efficiency in photosystem II. Chinese Journal of Plant Ecology, 2016, 40(11): 1208-1217. DOI: 10.17521/cjpe.2015.0470

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2015.0470

https://www.plant-ecology.com/CN/Y2016/V40/I11/1208

图/表 6

图1 剑叶金鸡菊(A)、黄荆(B)和大狼杷草(C)的电子传递速率对光的响应曲线(ETR-I)(平均值±标准误差)。公式(2)为ETR = α (1-β I) / (1 + γI) I, 其中α为ETR-I的初始斜率, β为光抑制项, γ为光饱和项, I为光强; 公式(9)为ETR =α'β'IΦPSIImax e-kwI, 其中α'为叶片光能吸收系数, β'为光能在2个光系统的分配比例, ΦPSIImax为光强为0时的最大光化学量子效率, kw是一个常数; 公式(11)为ETR = α'β'(Fv/Fm) PARsat [1-exp (-I/PARsat)], 其中Fv/Fm为光系统II的最大光量子效率, PARsat为饱和光强。

Fig. 1 Light-response curves of electron transport rate (ETR- I) for Coreopsis lanceolata (A), Vitex negundo (B) and Bidens frondosa (C) (mean ± SE). Equation (2) is ETR =α (1-β I) / (1 + γI) I. Here α is the initial slope of ETR-I, β is the photoinhibition term, γ is the saturation term, I is light intensity; Equation (9) is ETR =α'β'IΦPSIImaxe-kwI. Here α' is the light absorption coefficient of leaf, β' is the light energy distribution coefficient between photosystem II and photosystem I, ΦPSIImax is the maximum photochemical quantum efficiency while I = 0, kw is a constant; Equation (11) is ETR = α'β'(Fv/Fm) PARsat [1-exp(-I/PARsat)]. Here Fv/Fm is the maximum quantum of photosystem II, PARsat is the saturation irradiance.

表1 三种模型对三种植物光合电子流对光曲线的拟合参数

Table 1 The measured data and fitted values for Coreopsis lanceolata, Vitex negundo and Bidens frondosa using three models

光合参数 Photosynthetic parameter	剑叶金鸡菊 C. lanceolata						黄荆 V. negundo				大狼杷草 B. frondosa
光合参数 Photosynthetic parameter	公式(2) Equation (2)	公式(9) Equation (9)	公式(11) Equation (11)		测量值 Measured value		公式(2) Equation (2)	公式(9) Equation (9)	公式(11) Equation (11)	测量值 Measured value	公式(2) Equation (2)		公式(9) Equation (9)		公式(11) Equation (11)		测量值 Measured value
ETR-I的初始斜率 Initial slope of ETR-I (μmol·μmol^-1)	0.347	Φ_PSIImax (0.859)	F_v/F_m (0.954)		-		0.352	Φ_PSIImax (0.834)	F_v/F_m (0.928)	-	0.315		Φ_PSIImax (0.675)		F_v/F_m (0.820)		-
最大电子传递速率 Maximu electron transport rate (μmol·m^-2·s^-1)	232.3	231.3	156.5		230.4		230.2	229.8	155.99	≈228.8	136.7		137.28		86.67		≈135.8
饱和光强 Saturation irradiance (μmol·m^-2·s^-1)	1 641.7	1 742.2	617.83		≈1 600		1 740.9	1 782.5	633.1	≈1 750	1 394.5		1 326.3		395.2		≈1 400
叶绿素含量 Chlorophyll content (mg·m^-2)	253.68						268.18				286.33
本征截面 Eign-absorption cross section (10^-21 m²)	5.41	-		-		-	5.19	-	-	-	4.35	-		-		-
决定系数 Determined coefficient	1.000	0.998		0.995		-	0.999	0.999	0.997	-	0.998	0.997		0.995		-
AIC信息准则 Akaike’s information criterion	7.40	7.34		9.22		-	8.34	7.48	8.78	-	7.74	7.27		8.46		-

图2 剑叶金鸡菊(A)、黄荆(B)和大狼杷草(C)的实际光量子效率对光的响应曲线(ΦPSII-I)(平均值±标准误差)。公式(5)为ΦPSII = ω (1-βI) / (1 + γI), 其中ω为ΦPSII-I的初始斜率; 公式(8)为ΦPSII = ΦPSIImax e-kwI, 公式(10)为ΦPSII = (Fv/Fm) PARsat / I (1-exp(-I/PARsat))。β、γ、Fv/Fm、ΦPSIImax、kw和PARsat的定义同图1。

Fig. 2 Light-response curves of ΦPSII for Coreopsis lanceolata (A), Vitex negundo (B) and Bideas frondosa (C)(mean ± SE). Equation (5) is ΦPSII = ω (1-βI) / (1 + γI). Here ω is the initial slope of ΦPSII-I; Equation (8) is ΦPSII = ΦPSIImax e-kwI; Equation (10) is ΦPSII = (Fv/Fm) PARsat / I (1-exp(-I/PARsat)). The definition of β, γ, Fv/Fm, ΦPSIImax, kw and PARsat see Fig. 1.

表2 三种模型对三种植物叶片的ΦPSII-I曲线的拟合参数

Table 2 The measured data and fitted values for Coreopsis lanceolata, Vitex negundo and Bidens frondosa using three models

光合参数 Photosynthetic parameter	剑叶金鸡菊 C. lanceolata				黄荆 V. negundo				大狼杷草 B. frondosa
光合参数 Photosynthetic parameter	公式(5) Equation (5)	公式(8) Equation (8)	公式(10) Equation (10)	测量值 Measured value	公式(5) Equation (5)	公式(8) Equation (8)	公式(10) Equation (10)	测量值 Measured value	公式(5) Equation (5)	公式(8) Equation (8)	公式(10) Equation (10)	测量值 Measured value
Φ_PSII-I的初始斜率 Initial slope of Φ_PSII-I (μmol·μmol^-1)	0.763	Φ_PSIImax (0.771)	F_v/F_m (0.779)	-	0.752	Φ_PSIImax (0.759)	F_v/F_m (0.767)	-	0.665	Φ_PSIImax (0.678)	F_v/F_m (0.674)	-
饱和光强 Saturation irradiance (μmol·m^-2·s^-1)	1 642.9	1 744.9	824.95	≈1 600	1 712.7	1 763.3	830.33	≈1 750	1 406.7	1 331.2	448.50	≈1 400
决定系数 Determined coefficient	0.995	0.992	0.984	-	0.996	0.994	0.986	-	0.996	0.995	0.991	-
AIC信息准则 Akaike’s information criterion	-2.49	-2.75	-2.03	-	-2.79	-3.04	-2.20	-	-2.51	-3.06	-2.46	-

表3 三种模型对三种植物叶片的ΦPSII-I曲线的拟合参数(平均值±标准误差)

Table 3 The fitted values of ΦPSII-I curves for Coreopsis lanceolata, Vitex negundo and Bidens frondosa using three models (mean ± SE)

	剑叶金鸡菊 C. lanceolata		黄荆 V. negundo		大狼杷草 B. frondosa
	Φ_PSIImax	F_v/F_m	Φ_PSIImax	F_v/F_m	Φ_PSIImax	F_v/F_m
公式(8) Equation (8)	0.859 ± 0.011^a	-	0.834 ± 0.005^a	-	0.678 ± 0.059^a	-
公式(9) Equation (9)	0.771 ± 0.004^b	-	0.759 ± 0.006^b	-	0.675 ± 0.051^a	-
公式(10) Equation (10)	-	0.954 ± 0.019^a	-	0.928 ± 0.005^a	-	0.820 ± 0.079^a
公式(11) Equation (11)	-	0.779 ± 0.004^b	-	0.767 ± 0.006^b	-	0.674 ± 0.029^a
α/ω	0.455 ± 0.007^*		0.468 ± 0.008^*		0.474 ± 0.023^ns

图3 剑叶金鸡菊(A)、黄荆(B)和大狼杷草(C)的有效光能吸收截面对光的响应曲线(σ'ik-I)(平均值±标准误差)。

Fig. 3 Light-response curves of effective light energy absorption cross-section (σ'ik-I) for Coreopsis lanceolata (A), Vitex negundo (B) and Bidens frondosa (C)(mean ± SE).

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