Responses of PSII photochemistry efficiency and photosynthetic pigments of Saussurea superba to short-term UV-B-supplementation

doi:10.3724/SP.J.1258.2012.00420

Abstract

Abstract:

Aims Native alpine plants that have grown and evolved on the Qinghai-Tibetan Plateau of China for a long time have developed a strong adaptation capacity for harsh environmental factors, such as low temperature, low air pressure, strong sunlight and solar UV-B radiation. The objective of this study was to determine the response of PSII photochemistry efficiency to short-term enhanced solar UV-B intensity in alpine plants. We examined whether UV-B-absorbing compounds were sufficiently efficient to protect the photosynthetic apparatus from UV-B photo-inactivation or photo-damage and evaluated the influence of UV-B radiation on photosynthetic pigments.
Methods Field experiments were conducted during the 2008 and 2009 growing seasons in alpine Kobresia humilis meadow near Haibei Alpine Meadow Ecosystem Research Station (37°29°-37°45° N, 101°12°-101°33° E; alt. 3 200 m) using the native alpine plant Saussurea superba. Short-term UV-B-supplementation studies were performed over 5 days using UV-B-313 fluorescence lamps, which were filtered with a cellulose diacetate film to get increased UV-B treatment and a Mylar film as a control. Pulse-modulated in-vivo chlorophyll fluorescence was used to obtain rapid information of UV-B on photosynthetic processes. The 3-min dark-adapted maximum quantum efficiency of PSII photochemistry, F_(v)/F_(m), and PSII photochemistry efficiency were measured under natural sunlight. The contents of photosynthetic pigments and UV-B-absorbing compounds were analyzed based on leaf area unit.
Important findings Although there was no significant difference, F_(v)/F_(m) showed a decreasing trend after short-term exposure to enhanced UV-B radiation in all measurements throughout the growing season. The reduction of the actual photochemical quantum efficiency and photochemical quenching as well as the increase of non-photochemical quenching in UV-B supplemented treatment, when compared to the control, indicated there was a decrease in PSII photochemistry efficiency and an increase in non-photochemical quenching. These phenomena indicated photo-inactivation or photo-damage of photosynthesis occurred in the PSII reaction center. The photosynthetic pigments showed a small decrease in the UV-B supplemented treatment, which may be related to the enhancement of photo-oxidation, a reduction of pigment synthesis and small variation of leaf thickness. The UV-B-absorbing compounds were not influenced by short-term enhancement of UV-B radiation when analyzed based on leaf area unit. This demonstrated that higher contents of UV-B-absorbing compounds in the epidermal layer of alpine plant S. superba were efficient for defense against UV-B radiation and stabilized for further enhancement of UV-B radiation

Key words: alpine plant, photosynthetic pigment, PSII photochemistry efficiency, Qinghai-Tibetan Plateau, Saussurea superba, UV-B-absorbing compounds, UV-B radiation

SHI Sheng-Bo, SHANG Yan-Xia, SHI Rui, ZHANG Bo. Responses of PSII photochemistry efficiency and photosynthetic pigments of Saussurea superba to short-term UV-B-supplementation[J]. Chin J Plant Ecol, 2012, 36(5): 420-430.

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URL: https://www.plant-ecology.com/EN/10.3724/SP.J.1258.2012.00420

https://www.plant-ecology.com/EN/Y2012/V36/I5/420

Figures/Tables 6

Table 1 Changes of main environmental factors in short-term UV-B-supplementation experiments in July 14, 2009 (mean ± SE, n = 15; α = 0.05)

	增补UV-B辐射 Enhanced UV-B	背景UV-B辐射 Ambient UV-B	差异显著性 Significance
光合有效辐射 PAR (μmol photons·m^-2·s^-1)	1 842 ± 33	1 825 ± 32	0.720 6
相对湿度 Relative humidity (%)	70.98 ± 0.20	71.07 ± 0.16	0.740 1
气温 Air temperature (℃)	20.43 ± 0.15	20.44 ± 0.11	0.971 1
UV-B (W·m^-2)	4.40 ± 0.06	4.28 ± 0.05	0.061 0
UV-A (mW·m^-2)	23.54 ± 0.14	22.12 ± 0.06	0

Fig. 1 Effects of short-term UV-B-supplementation on 3-min dark adapted and light adapted maximum quantum efficiency of PSII photochemistry (F(v)/F(m) (A) and (Fv′/Fm′) (B)) in Saussurea superba during plants growing season in 2008 (mean ± SE).

Fig. 2 Effects of short-term UV-B supplementation on photochemical and non-photochemical quenching (qP) (A) and (NPQ) (B) in Saussurea superba during plants growing season in 2008 (mean ± SE).

Fig. 3 Effects of short-term UV-B supplementation on photosynthetic pigment contents in Saussurea superba measured in different months during the plant growing season in 2008 (mean ± SE, n = 6). Car, carotinoid; Chl, chlorophyll. *, Significant difference between the treatments (p < 0.05).

Fig. 4 Influence of short-term UV-B radiation on UV-B-abs- orbing compounds in Saussurea superba in different months during plant growing season in 2008 (mean ± SE, n = 6).

Fig. 5 Influence of short-term UV-B radiation on leaf weight ratio in Saussurea superba in different months during plant growing season in 2008 (mean ± SE, n = 6).

References 37

[1]	Allen DJ, Nogués S, Baker NR (1998). Ozone depletion and increased UV-B radiation: Is there a real threat to photosynthesis? Journal Experimental Botany, 49, 1775-1788.
[2]	Baker NR (2008). Chlorophyll fluorescence: a probe of photosynthesis in vivo. Annual Review of Plant Biology, 59, 89-113. DOI URL PMID
[3]	Bilger W, Björkman O (1990). Role of the xanthophyll cycle in photoprotection elucidated by measurements of light- induced absorbance changes, fluorescence and photosynthesis in leaves of Hedera canariensis. Photosynthesis Research, 25, 173-185. DOI URL PMID
[4]	Bilger W, Johnsen T, Schreiber U (2001). UV-excited chlorophyll fluorescence as a tool for the assessment of UV-protection by the epidermis of plants. Journal Experimental Botany, 52, 2007-2014.
[5]	Björn LO (1999). Ultraviolet radiation, the ozone layer and ozone depletion. In: Rozema J ed. The Effects of Enhanced UV-B Radiation on Terrestrial Ecosystem. Backhuys, Leiden, the Netherlands. 21-27.
[6]	Björn LO, Teramura AH (1993). Simulation of daylight ultraviolet radiation and effects of ozone depiction. In: Young AR, Björn LO, Moan J, Nultsch W eds. Environmental UV Photobiology. Plenum Press, New York. 41-71.
[7]	Bornman JF (1989). Target sites of UV-B radiation in photosynthesis of higher plants. Journal of Photochemistry and Photobiology B: Biology, 4, 145-158.
[8]	Britt AB (1999). Molecular genetics of DNA repair in higher plants. Trends in Plant Science, 4, 20-25. URL PMID
[9]	Caldwell MM, Flint SD (1994). Stratospheric ozone reduction, solar UV-B radiation and terrestrial ecosystems. Climate Change, 28, 375-394. DOI URL
[10]	Costa H, Gallego SM, Tomaro ML (2002). Effect of UV-B radiation on antioxidant defense system in sunflower cotyledons. Plant Science, 162, 939-945. DOI URL
[11]	Flint SD, Ryel RJ, Caldwell MM (2003). Ecosystem UV-B experiments in terrestrial communities: a review of recent findings and methodologies. Agricultural and Forest Meteorology, 120, 177-189. DOI URL
[12]	Galvez-Valdivieso G, Fryer MJ, Lawson T, Slattery K, Truman W, Smirnoff N, Asami T, Davies WJ, Jones AM, Baker NR, Mullineaux PM (2009). The high light response in Arabidopsis involves ABA signaling between vascular and bundle sheath cells. The Plant Cell, 21, 2143-2162. DOI URL PMID
[13]	Genty B, Briantais JM, Baker NR (1989). The relationship between the quantum yield of photosynthetic electron transport and quenching of chlorophyll fluorescence. Biochimica et Biophysica Acta (BBA)-General Subjects, 990, 87-92. DOI URL
[14]	Jansen MAK, Gaba V, Greenberg BM (1998). Higher plants and UV-B radiation: balancing damage, repair and acclimation. Trends in Plant Science, 3, 131-135. DOI URL
[15]	Joshi PN, Ramaswamy NK, Iyler RK, Nair JS, Pradhan MK, Gartia S, Biswal B, Biswal UC (2007). Partial protection of photosynthetic apparatus from UV-B-induced damage by UV-A radiation. Environmental and Experimental Botany, 59, 166-172. DOI URL
[16]	Lau TSL, Eno E, Goldstein G, Smith C, Christopher DA (2006). Ambient levels of UV-B in Hawaii combined with nutrient deficiency decrease photosynthesis in near- isogenic maize lines varying in leaf flavonoids: flavonoids decrease photoinhibition in plants exposed to UV-B. Photosynthetica, 44, 394-403. DOI URL
[17]	Lizana XC, Hess S, Calderini DF (2009). Crop phenology modifies wheat responses to increased UV-B radiation. Agricultural and Forest Meteorology, 149, 1964-1974. DOI URL
[18]	Madronich S, Velders G, Daniel J, Lal M, McKulloch A, Slaper H (1999). Halocarbon scenarios for the future ozone layer and related consequence. In: Albritton D, Aucamp P, Megie G, Watson R eds. Scientific Assessment of Ozone Depletion: 1998. World Meteorological Organization, Geneva. 11.1-11.38.
[19]	McKenzie RL, Aucamp PJ, Bais AF, Björn LO, Ilyasd M (2007). Changes in biologically-active ultraviolet radiation reaching the Earth’s surface. Photochemical and Photobiological Sciences, 6, 218-231. URL PMID
[20]	Middleton EM, Teramura AH (1993). The role of flavonol glycoside and carotenoids in protecting soybean from ultraviolet-B damage. Plant Physiology, 103, 475-480.
[21]	Oxborough K, Baker NR (1997). Resolving chlorophyll a fluorescence images of photosynthetic efficiency into photochemical and non-photochemical components: calculation of q_P and F_v′/F_m′ without measuring F_o′. Photosynthesis Research, 54, 135-142. DOI URL
[22]	Paul ND, Gwynn-Jones D (2003). Ecological roles of solar UV radiation: towards an integrated approach. Trends in Ecology and Evolution, 18, 48-55. DOI URL
[23]	Quick WP, Stitt M (1989). An examination of factors contributing to non-photochemical quenching of chlorophyll fluorescence in barley leaves. Biochimica et Biophysica Acta (BBA)-Bioenergetics, 977, 287-296. DOI URL
[24]	Shi SB (师生波), Ben GY (贲桂英), Han F (韩发) (1999). Analysis of the solar UV-B radiation and plant UV-B- absorbing compounds in different regions. Acta Phytoecologica Sinica (植物生态学报), 23, 529-535. (in Chinese with English abstract)
[25]	Shi SB (师生波), Shang YX (尚艳霞), Zhu PJ (朱鹏锦), Yang L (杨莉) (2011a). Effects of short term enhanced UV-B radiation on the PSII photochemical efficiency of alpine plant Saussurea superba. Chinese Journal of Applied Ecology (应用生态学报), 22, 1147-1154. (in Chinese with English abstract) URL PMID
[26]	Shi SB (师生波), Shang YX (尚艳霞), Zhu PJ (朱鹏锦), Yang L (杨莉), Zhang B (张波) (2011b). Effects of solar UV-B radiation on the efficiency of PSII photochemistry in the alpine plant Saussurea superba under different weather conditions in the Qinghai-Tibet Plateau of China. Chinese Journal of Plant Ecology (植物生态学报), 35, 741-750. (in Chinese with English abstract) DOI URL
[27]	Shi SB (师生波), Shang YX (尚艳霞), Zhu PJ (朱鹏锦), Zhang DG (张德罡) (2010). Effect of enhanced UV-B radiation on photosynthesis and photosynthetic pigments in alpine plants Saussurea superba. Acta Agrectir Sinica (草地学报), 18, 607-614. (in Chinese with English abstract)
[28]	Shi SB (师生波), Shang YX (尚艳霞), Zhu PJ (朱鹏锦), Zhang DG (张德罡) (2011 c). Effects of UV-B exclusion on photosynthetic physiology in alpine plant Saussurea superba. Chinese Journal of Plant Ecology (植物生态学报), 35, 176-186. (in Chinese with English abstract) DOI URL
[29]	Shi SB, Zhu WY, Li HM, Zhou DW, Han F, Zhao XQ, Tang YH (2004). Photosynthesis of Saussurea superba and Gentiana straminea is not reduced after long-term enhancement of UV-B radiation. Environmental and Experimental Botany, 51, 75-83. DOI URL
[30]	Sicora C, Szilárd A, Sass L, Turcsányi E, Máté Z, Vass I (2006). UV-B and UV-A radiation effects on photosynthesis at the molecular level. In: Ghetti F, Checcucci G, Bornman JF eds. Environmental UV Radiation: Impact and Human Health and Predictive Model. Springer, the Netherlands. 121-135.
[31]	Šprtová M, Špunda V, Kalina J, Marek MV (2003). Photosynthetic UV-B response of beach (Fagus sylvatica L.) saplings. Photosynthetic, 41, 533-543. DOI URL
[32]	van de Staaij JWM, Huijsmans R, Ernst WHO, Rozema J (1995). The effect of elevated UV-B (280-320 nm) radiation levels on Silene vulgaris: a comparison between a highland and a lowland population. Environmental Pollution, 90, 357-362. URL PMID
[33]	van Rensen JJS, Vredenberg WJ, Rodrigues GC (2007). Time sequence of the damage to the acceptor and donor sides of photosystem II by UV-B radiation as evaluated by chlorophyll a fluorescence. Photosynthesis Research, 94, 219-297.
[34]	Xu DQ (许大全) (2002). Photosynthetic Efficiency (光合作用效率). Shanghai Scientific and Technical Press, Shanghai. (in Chinese)
[35]	Zhang SR (张守仁) (1999). A discussion on chlorophyll fluorescence kinetics parameters and their significance. Chinese Bulletin of Botany (植物学通报), 16, 444-448. (in Chinese with English abstract)
[36]	Zhu GL (朱广廉), Zhong HW (钟诲文), Zhang AQ (张爱琴) (1990). The Plant Physiological Experiment (植物生理学实验). Beijing University Press, Beijing. 51-54. (in Chinese)
[37]	Ziska LH, Termura AH, Sullivan JH (1992). Physiological sensitivity of plants along an elevational gradient to UV-B radiation. American Journal of Botany, 79, 863-871. DOI URL