环境强光诱导玉簪叶片光抑制的机制

doi:10.3724/SP.J.1258.2014.00067

摘要/Abstract

摘要：

为进一步阐述光抑制的强光诱导和发生机制, 该文以喜阴植物玉簪(Hosta spp.)为材料研究其光抑制发生规律及其与环境光强的关系。结果表明, 全日照和遮阴条件下玉簪叶片发育分别形成适应强光和弱光的形态特征; 与遮阴处理相比, 强光下生长的玉簪光合速率和叶绿素含量较低, 但两种处理叶片最大光化学效率差异很小, 证明强光下植株可以正常生长且光合机构未发生严重的光抑制。将遮阴处生长的植株转移到全日照下, 光合速率和最大光化学效率急剧下降; 荧光诱导动力学曲线发生明显改变, 而且光系统II供体侧和受体侧荧光产量的变化幅度分别达到24.3%和34.2%, 表明玉簪由弱光转入强光后光系统II发生不可逆失活, 且受体侧受到的伤害较供体侧更严重。因此, 作者认为环境光强骤然提高并超过玉簪生长光强时很容易诱导其光合机构发生严重的光抑制。该研究对于理解植物适应光环境的策略以及喜阴植物的优质栽培有重要意义。

关键词: 叶绿素荧光, 强光, 光抑制, 光合作用, 光系统II

Abstract:

Aims It has long been recognized that photoinhibition of photosynthesis is induced by high light. However, our recent studies are not consistent with this traditional view. Therefore, the objective of this study is to explore the induction of photoinhibition and its mechanisms under full sunlight outdoors.
Methods Changes of leaf morphology, gas exchange, and chlorophyll a fluorescence were measured to investigate the induction and mechanisms of photoinhibition under high light in Hosta, which is a typical shade-tolerant plant.
Important findings Hosta plants grown under full sunlight (HT) and low light (LT) developed sun- and shade-type leaf morphological characteristics, respectively. Under a full sunlight, Hosta plants had lower photosynthetic rate and chlorophyll content than under the LT; whereas, there were only slight difference in the maximum quantum yield of photosystem II (F_v/F_m) between the two treatments, suggesting that Hosta plants could grow normally under full sunlight without severe photoinhibition. After transition from the low to a high light (LHT), the photosynthetic rate and maximum quantum yield of photosystem II decreased sharply, reflecting that the LHT treatment led to irreversibly inactivation of photosystem II. Additionally, the shape of chlorophyll a fluorescence transients also changed significantly; the relative fluorescence yield of the K and J steps were reduced by 24.3% and 34.2%, respectively, indicating that the acceptor side of photosystem II was damaged more severely than the donor side. Consequently, we postulate that photoinhibition in Hosta leaves is mainly induced by the sudden enhancement of light intensity outdoors. Hosta can acclimate to high irradiance through leaf development outdoors. Our finding is of great significance in understanding the acclimation of plants to high light and cultivation of shade-tolerant plants in field.

Key words: chlorophyll a fluorescence, high light, photoinhibition, photosynthesis, photosystem II

李志真, 刘东焕, 赵世伟, 姜闯道, 石雷. 环境强光诱导玉簪叶片光抑制的机制. 植物生态学报, 2014, 38(7): 720-728. DOI: 10.3724/SP.J.1258.2014.00067

LI Zhi-Zhen, LIU Dong-Huan, ZHAO Shi-Wei, JIANG Chuang-Dao, SHI Lei. Mechanisms of photoinhibition induced by high light in Hosta grown outdoors. Chinese Journal of Plant Ecology, 2014, 38(7): 720-728. DOI: 10.3724/SP.J.1258.2014.00067

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链接本文: https://www.plant-ecology.com/CN/10.3724/SP.J.1258.2014.00067

https://www.plant-ecology.com/CN/Y2014/V38/I7/720

图/表 8

图1 光强对玉簪叶面积、比叶重、叶片数和叶绿素含量的影响(平均值±标准误差, n = 6)。不同大、小写字母分别表示自然光和遮阴处理后叶面积、比叶重、叶片数和叶绿素含量差异显著(p = 0.05)。HT, 全日照处理; LT, 遮阴处理。

Fig. 1 Effects of light intensity on leaf area, specific leaf weight, leaf number and chlorophyll (a + b) content in Hosta leaves (mean ± SE, n = 6). Different capital letters and lowercase letters indicate significant differences in leaf area, specific leaf weight, leaf number, and chlorophyll (a + b) content between the HT and LT treatments, respectively (p = 0.05). HT, full sunlight; LT, low light.

图2 光强对玉簪叶片净光合速率(Pn)和气孔导度(Gs)的影响(平均值±标准误差, n = 6)。不同小写字母分别表示全日照(HT)和遮阴(LT)处理后叶片净光合速率和气孔导度的差异显著(p = 0.05)。

Fig. 2 Effects of light intensity on net photosynthetic rate (Pn) and stomatal conductance (Gs) in Hosta leaves (mean ± SE, n = 6). Different lowercase letters indicate significant differences in Pn and Gs between the full sunlight (HT) and low light (LT) treatments, respectively (p = 0.05).

图3 光强对玉簪叶片最大光化学效率(Fv/Fm)的影响(平均值±标准误差, n = 12)。不同小写字母表示全日照(HT)和遮阴(LT)处理后叶片Fv/Fm的差异显著(p = 0.05)。

Fig. 3 Effects of light intensity on the maximum quantum yield of photosystem II photochemistry (Fv/Fm) in Hosta leaves (mean ± SE, n = 12). Different lowercase letters indicate significant difference in Fv/Fm between the full sunlight (HT) and low light (LT) treatments, respectively (p = 0.05).

图4 遮阴转入全日照后玉簪叶片净光合速率(Pn)和气孔导度(Gs)的变化(平均值±标准误差, n = 6)。不同大、小写字母分别代表LT和LHT处理后叶片净光合速率和气孔导度的差异显著(p = 0.05)。LHT, 遮阴转入全日照处理; LT, 遮阴处理。

Fig. 4 Changes in the net photosynthetic rate (Pn) and stomatal conductance (Gs) after transfer from low light to full sunlight in Hosta leaves (mean ± SE, n = 6). Different capital letters and lowercase letters indicate significant differences in Pn and Gs between the LT and LHT treatments, respectively (p = 0.05). LHT, transition from low light to full sunlight; LT, low light.

图5 遮阴转入全日照后玉簪叶片最大光化学效率(Fv/Fm)的变化(平均值±标准误差, n = 12)。不同小写字母表示遮阴处理(LT)和遮阴转全日照处理(LHT)后叶片Fv/Fm的差异显著(p = 0.05)。

Fig. 5 Changes in the maximal photochemical efficiency (Fv/Fm) after transfer from low light to full sunlight in Hosta leaves (mean ± SE, n = 12). Different lowercase letters indicate significant differences in Fv/Fm between the low light (LT) and transition from low light to full sunlight (LHT) treatments, respectively (p = 0.05).

图6 遮阴转入全日照后玉簪叶片快速荧光诱导动力学曲线(OJIP曲线)的变化。LHT, 遮阴转全日照处理; LT, 遮阴处理。day0、day2、day4分别表示转入全日照前和转入全日照下2天和4天。

Fig. 6 Changes in the chlorophyll a fluorescence transients (fluorescence plotted on logarithmic time scale) following transfer from low light to full sunlight in Hosta leaves. LHT, transition from low light to full sunlight; LT, low light. day0, day2, day4 represent grow under low light, and transferred to full sun light for two and four days.

图7 遮阴转入全日照后玉簪叶片快速荧光诱导动力学曲线WO-J和ΔWO-J的变化(时间坐标为线性形式)。LHT, 遮阴转全日照处理; LT, 遮阴处理。day0、day2、day4分别表示转入全日照前和转入全日照下2天和4天。

Fig. 7 Changes in WO-J and ΔWO-J in chlorophyll a fluorescence transients (plotted on a linear time scale) after transfer from low light to full sunlight in Hosta leaves. LHT, transition from low light to full sunlight; LT, low light. day0, day2, day4 represent grow under low light, and transferred to full sun light for two and four days.

表1 遮阴转入全日照后快速叶绿素荧光诱导动力学曲线(OJIP曲线)参数的变化(平均值±标准误差, n = 12)

Table 1 Changes in the chlorophyll fluorescence transient parameters after transfer from low light to full sunlight in Hosta leaves (mean ± SE, n = 12)

移栽后 Days after transfer		F_o	F_m	d_V/d_t₀	ψ₀	φ_Eo	φ_Do	PI_ABS
0	LT	507 ± 19.43^a	2 865 ± 63.21^a	0.702 3 ± 0.03^a	0.572 3 ± 0.01^a	0.454 1 ± 0.01^a	0.207 5 ± 0.01^a	26.32 ± 2.01^a
0	LHT	507 ± 19.43^a	2 865 ± 63.21^a	0.702 3 ± 0.03^a	0.572 3 ± 0.01^a	0.454 1 ± 0.01^a	0.207 5 ± 0.01^a	26.32 ± 2.01^a
2	LT	501 ± 13.27^a	2 656 ± 58.19^a	0.698 4 ± 0.02^a	0.585 8 ± 0.01^ab	0.457 7 ± 0.01^a	0.219 1 ± 0.00^a	24.26 ± 1.86^a
2	LHT	562 ± 31.09^b	1 437 ± 186.2^b	0.867 8 ± 0.05^b	0.469 8 ± 0.01^c	0.245 5 ± 0.03^b	0.488 3 ± 0.05^b	4.28 ± 1.11^b
4	LT	500 ± 9.71^a	2 765 ± 69.86^a	0.656 1 ± 0.02^a	0.611 8 ± 0.01^b	0.483 0 ± 0.00^a	0.210 5 ± 0.00^a	27.95 ± 1.03^a
4	LHT	641 ± 17.91^c	1 756 ± 87.01^c	0.962 4 ± 0.03^b	0.501 7 ± 0.01^d	0.296 7 ± 0.01^c	0.409 3 ± 0.02^c	4.74 ± 0.47^b

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