海水升温及紫外辐射对威氏海链藻光合特性的影响

doi:10.17521/cjpe.2024.0228

摘要/Abstract

摘要： 硅藻是海洋浮游植物的重要组成部分, 其光合产量达到海洋初级生产力的40%以上。阳光紫外辐射(UVR)增强和海水升温的耦合作用将会影响硅藻的光合作用, 进而影响其初级生产贡献。该研究主要探索升温对硅藻响应UVR的光合生理调控, 以进一步了解海洋环境变化对硅藻光合作用的影响。将威氏海链藻(Thalassiosira weissflogii)在18和24 ℃下培养, 并置于高可见光(光合有效辐射(PAR) 400-700 nm)和UVR (PAR+UVR, 280-700 nm)下, 以监测其光系统II (PSII)功能变化和相关生理响应。结果表明: PAR和PAR+UVR均对威氏海链藻PSII最大光化学效率(F_v/F_m)产生抑制作用, UVR存在下PSII光失活速率常数(K_pi)显著上升, 但升温时, UVR下威氏海链藻细胞具有与低温下相近的PSII修复速率常数与失活速率常数比值(K_rec/K_pi)。对PSII蛋白亚基周转的分析表明, 可见光下升温使威氏海链藻细胞维持较高的D2蛋白(PsbD)库, 而在UVR下升温则协同促进受损D1蛋白(PsbA)的快速清除。此外, 升温条件下威氏海链藻细胞维持较高的超氧化物歧化酶和过氧化氢酶活性, 各处理下仅诱导产生较低水平的非光化学淬灭。该研究结果表明, 威氏海链藻在升温时可通过调节PSII修复循环以促进其光合性能对抗UVR的抑制效应。

关键词: 硅藻, 光合作用, 升温, 紫外辐射, 威氏海链藻

Abstract:

Aims Diatoms are an important component of marine phytoplankton, and their photosynthetic production reaches more than 40% of the ocean primary productivity. The combined effects of enhanced solar ultraviolet radiation (UVR) and seawater warming will affect the photosynthesis of diatoms and their contribution to the primary productivity. In this study, we mainly explored the photosynthetic physiological regulation of diatoms in response to UVR radiation by warming, in order to further understand the effects of marine environmental changes on the photosynthesis of diatoms.

Methods Thalassiosira weissflogii was cultured at 18 °C and 24 °C and exposed to high visible light (photosynthetically active radiation (PAR), 400-700 nm) and UVR (PAR+UVR, 280-700 nm) to monitor changes in photosystem II (PSII) function and other physiological responses.

Important findings PAR and PAR+UVR inhibited the maximum photochemical efficiency (F_v/F_m) of PSII in T. weissflogii. The photoinactivation rate constant (K_pi) of PSII increased significantly in the presence of UVR. The ratio of repair rate constant to photoinactivation rate constant of PSII (K_rec/K_pi) in UVR was similar to that under low temperature. Analysis of PSII subunit turnover showed that warming under visible light allowed cells to maintain a high D2 (PsbD) pool, whereas warming under UVR synergistically promoted rapid clearance of damaged D1 (PsbA). In addition, the activities of superoxide dismutase and catalase were higher in the cells under the increased temperature, and low level of non-photochemical quenching was induced under all treatments. Our results showed that warming can promote the photosynthetic performance of T. weissflogii by adjusting its PSII repair cycle to counteract the inhibitory effect of UVR.

Key words: diatoms, photosynthesis, warming, ultraviolet radiation, Thalassiosira weissflogii

甄玉琪, 邓晨茜, 鲍梦林, 臧纱纱, 严芳, 吴红艳. 海水升温及紫外辐射对威氏海链藻光合特性的影响. 植物生态学报, 2025, 49(11): 1934-1943. DOI: 10.17521/cjpe.2024.0228

ZHEN Yu-Qi, DENG Chen-Xi, BAO Meng-Lin, ZANG Sha-Sha, YAN Fang, WU Hong-Yan. Effects of ocean warming and ultraviolet radiation on the photosynthetic characteristics of Thalassiosira weissflogii. Chinese Journal of Plant Ecology, 2025, 49(11): 1934-1943. DOI: 10.17521/cjpe.2024.0228

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https://www.plant-ecology.com/CN/Y2025/V49/I11/1934

图/表 7

图1 18 ℃和24 ℃条件下, 威氏海链藻光系统II最大光化学效率(Fv/Fm)对光辐射的响应(平均值±标准误, n = 4)。藻细胞在PAR和PAR+UVR下照射90 min, 并在低光下恢复30 min。虚线表示高光暴露与恢复期的划分。Lin, 林肯霉素; PAR, 光合有效辐射; UVR, 紫外线辐射。不同小写字母表示处理间存在显著差异(p < 0.05)。

Fig. 1 Maximum photochemical yield (Fv/Fm) changes in Thalassiosira weissflogii cells grown at 18 °C or 24 °C treated without or with lincomycin (+Lin) when exposed to PAR or PAR + UVR for 90 min and low growth light for 30 min (mean ± SE, n = 4). The division between high light exposure and recover period was indicated by the dotted line. PAR, photosynthetically active radiation; UVR, ultraviolent radiation. Different lowercase letters indicate significant differences between treatments (p < 0.05).

表1 不同处理下威氏海链藻光系统II (PSII)修复速率常数(Krec, s-1)和光失活速率常数(Kpi, s-1)及Krec与Kpi的比值(平均值±标准误, n = 4)

Table 1 Rate constant for photosystem II (PSII) repair (Krec, s-1) and photoinactivation (Kpi, s-1) and the ratio of Krec to Kpi for various treatments in Thalassiosira weissflogii (mean ± SE, n = 4)

温度 Temperature	处理 Treatment	K_rec	K_pi	K_rec/K_pi
18 ℃	PAR	0.005 459 ± 0.000 656^a	0.000 189 ± 0.000 013^b	28.9
	PAR+UVR	0.005 403 ± 0.000 146^a	0.000 521 ± 0.000 036^a	10.4
24 ℃	PAR	0.006 946 ± 0.001 114^a	0.000 129 ± 0.000 008^c	53.8
	PAR+UVR	0.004 947 ± 0.000 247^b	0.000 487 ± 0.000 003^a	10.2

图2 18 ℃和24 ℃条件下光辐射对威氏海链藻PsbA蛋白相对含量的影响(平均值±标准误, n = 4)。藻细胞在PAR和PAR+ UVR下照射90 min, 并在低光下恢复30 min。虚线表示高光暴露与恢复期的划分。Lin, 林肯霉素; PAR, 光合有效辐射; UVR, 紫外线辐射。不同小写字母表示不同处理下存在显著差异(p < 0.05)。

Fig. 2 PsbA relative content changes in Thalassiosira weissflogii cells grown at 18 °C or 24 °C treated without or with lincomycin (+Lin) when exposed to PAR or PAR + UVR for 90 min and low growth light for 30 min (mean ± SE, n = 4). The division between high light exposure and recover period was indicated by the dotted line. PAR, photosynthetically active radiation; UVR, ultraviolet radiation. Different lowercase letters indicate significant differences under different treatments (p < 0.05).

图3 18 ℃和24 ℃下威氏海链藻在不同辐射处理下PsbA清除速率常数(KPsbA)的变化(平均值±标准误, n = 4)。PAR, 光合有效辐射; UVR, 紫外辐射。不同小写字母表示不同处理间存在显著差异(p < 0.05)。

Fig. 3 Removal rate constant of PsbA (KPsbA) in Thalassiosira weissflogii grown at 18 °C or 24 °C (mean ± SE, n = 4). PAR, photosynthetically active radiation; UVR, ultraviolet radiation. Different lowercase letters indicate significant differences under different treatments (p < 0.05).

图4 18 ℃和24 ℃条件下PAR及PAR+UVR对威氏海链藻的PsbA和PsbD蛋白相对含量的影响(平均值±标准误, n = 3)。PAR, 光合有效辐射; UVR, 紫外辐射。

Fig. 4 PsbA relative content versus PsbD relative content in Thalassiosira weissflogii grown at 18 °C or 24 °C exposed to PAR and PAR + UVR (mean ± SE, n = 3). PAR, photosynthetically active radiation; UVR, ultraviolet radiation.

图5 18 ℃和24 ℃条件下光辐射对威氏海链藻非光化学淬灭(NPQs)的影响(平均值±标准误, n = 4)。藻细胞在PAR和PAR+ UVR下照射90 min, 并在低光下恢复30 min。虚线表示高光暴露与恢复期的划分。Lin, 林肯霉素; PAR, 光合有效辐射; UVR, 紫外线辐射。不同小写字母表示不同处理间存在显著差异(p < 0.05)。

Fig. 5 Non-photochemical quenching (NPQs) changes in Thalassiosira weissflogii cells grown at 18 °C or 24 °C treated without or with lincomycin (+Lin) when exposed to PAR or PAR + UVR for 90 min and low growth light for 30 min (mean ± SE, n = 4). The division between high light exposure and recover period was indicated by the dotted line. PAR, photosynthetically active radiation; UVR, ultraviolet radiation. Different lowercase letters indicate significant differences under different treatments (p < 0.05).

图6 18 ℃ (A、C)和24 ℃ (B、D)条件下光辐射对威氏海链藻超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性的影响(平均值±标准误, n = 4)。藻细胞在PAR和PAR+UVR下照射90 min, 并在低光下恢复30 min。虚线表示高光暴露与恢复期的划分。PAR, 光合有效辐射; UVR, 紫外线辐射。相同小写字母表示不同处理间不存在显著性差异(p ≥ 0.05)。

Fig. 6 Superoxide dismutase (SOD) and catalase (CAT) activity changes in Thalassiosira weissflogii cells grown at 18 °C (A, C) or 24 °C (B, D) when exposed to PAR or PAR + UVR for 90 min and low growth light for 30 min (mean ± SE, n = 4). The division between high light exposure and recover period was indicated by the dotted line. PAR, photosynthetically active radiation; UVR, ultraviolet radiation. Same lowercase letters indicate no significant differences under different treatments (p ≥ 0.05).

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