Effects of Enhanced Ultraviolet B Irradiation on Photosynthetic and Antioxidant System of Sorghum Seedlings
SHI Xin-xin1, 2, 3, LI Zuo-tong1, 2*, YANG Ke-jun1, 2, ZHAO Chang-jiang1, 2, 3*, YANG Rong -bin4, YU Gao-bo1, HUANG Shou-guang1, XU Jing-yu1, 2, HE Lin1, 2, ZHAO Ying1, XU Yan-mei1, MA Li-feng1, FAN Bo-wen1
1. College of Agronomy Heilongjiang Bayi Agricultural University, Daqing 163319, China 2. Key Laboratory of Crop Germplasm Improvement and Cultivation in Cold Regions of Heilongjiang Province Education Department, Daqing 163319, China 3. National Engineering Research Center for Coarse Cereals, Daqing 163319, China 4. Beidahuang Ken Feng Seed Industry, Heihe 164000, China
Abstract:The UV-B radiation on the surface of our planet has been enhanced due to gradual thinning of ozone layer. The change of solar spectrum UV-B radiation will cause damage to all kinds of terrestrial plants at certain degree. In this paper, taking breeding sorghum (Sorghum bicolor (L.Moench))variety Longza No.5 as sample, 40 μW·cm-2 UV-B radiation treatment was conducted on sorghum seedlings at two-leaf and one-heart stage and different time courses; then after a 2 d recovering, photosynthetic parameters were measured with a photosynthetic apparatus; the activities of antioxidant enzymes were detected as well. Our results revealed that, as the dosages of UV-B increasing, leaf browning injury was aggravated, plants dwarfing and significantly were reduced fresh weight and dry weight were observed; anthocyanin content was significantly increased; chlorophyll and carotenoid content significantly were reduced and net photosynthetic rate and chlorophyll fluorescence parameters were decreased. Meanwhile, with the increase in UV-B dosages, stomatal conductance, intercellular CO2 concentration and transpiration rate showed “down - up - down” trend; the activities of SOD and GR presented “down - up” changes; activities of POD and CAT demonstrated “down - up - down”, and APX, GPX showed an “up - down - up” pattern. It is worth to note that, under the four-dose treatment, a sharp decline in net photosynthesis in sorghum seedlings was observed at 6 h UV-B treatment (equals to 2.4 J·m-2), and an obvious turning point was also found for other photosynthetic parameters and activities of antioxidant enzymes at the same time point. In summary, the results indicated that the enhanced UV-B radiation directly accounted for the damages in photosynthesis system including photosynthetic pigment content, net photosynthetic rate and chlorophyll fluorescence parameters of sorghum; the antioxidant system showed different responses to UV-B radiation below or above 6 h treatment: ASA-GSH cycle was more sensitive to low-dose UV-B radiation, while high-dose UV-B radiation not only undermined the photosynthesis system, but also triggered plant enzymatic and non-enzymatic antioxidant systems, resulting in leaf browning and necrosis,biomass accumulation reduction, plant dwarfing and even death.
[1] CAI Mei-ju, FENG HU-yuan, AN Li-zhe, et al(蔡美菊, 冯虎元, 安黎哲, 等). Chinese Journal of Applied Ecology(应用生态学报), 2002, 13(3): 359. [2] Biggs R H, Kouthus S V. UV-B Biological and Climate Effects Research Final Report US Department of Agriculture University of Florida Press, Gainesville, 1978. [3] Caldwel M M. Physiology (New Serries), Springer Verlay, 1981, 12A: 169. [4] Archana A, Eric S M, May R B, et al. Journal of Chemical Ecology, 1993, 19(12): 2813. [5] Jordan B R, HE J, Chow W S, et al. Plant Cell Environment, 1992, 15(1): 91. [6] Jorden B R, James P E, Strid A, et al. Plant Cell and Environment, 1994, 17 (1): 45. [7] TANG Xu-dong, AN Li-zhe, WANG Xun-ling(唐旭东, 安黎哲, 王勋陵). Academic of Plant Physiology(植物生理学报), 1998, 24(2): 171. [8] YAN Bin, DAI Qiu-jie(宴 斌, 戴秋杰). Academic of Plant Physiology(植物生理学报), 1996, 22(4): 373. [9] Krizek D T. Plant Physiology, 1993, 90(3): 593. [10] ZHANG Zhi-liang(张志良). Handbook of Plant Physiology Experiment(植物生理学实验指导). Beijing: Higher Education Press(北京: 高等教育出版社), 1990. [11] WANG Xue-kui(王学奎). Principle and Technology of Plant Physiological and Biochemical Experiments(植物生理生化实验原理和技术). Beijing: Higher Education Press(北京: 高等教育出版社), 2006. [12] Giannopolitis C N, Ries S K. Plant Physiology, 1977, 59: 309. [13] Britton C, Mehley A C. Methods in Enzymology. Academic Press, New York, 1955. 764. [14] Aebi H. Methods Enzymol.,1984, 105:121. [15] Nakano Y, Asada K. Plant and Cell Physiology, 1981, 22: 867. [16] Egley G H, Paul R N, Vaughn K C, et al. Planta, 1983, 157: 224. [17] Schaedle M, Bassham J A. Plant Physiology, 1977, 59: 1011. [18] Barnes P W, Fijnt S D, Caldwell M M. American Journal of Botany, 1990, 77(10): 1354. [19] Buer C S, Muday G K. Plant Cell, 2004, 16: 1191. [20] Kakani V G, Reddy K R, Zhao D, et al. Agricultural and Forest Meteorology, 2003, 120(1/4): 191. [21] Jenkins G. Plant Cell & Environment, 1997, 20(6): 773. [22] YANG Jing-hong, CHEN Tuo, WANG Xun-ling(杨景宏, 陈 拓, 王勋陵). Chinese Journal of Plant Ecology(植物生态学报), 2000, 24(2): 102. [23] Well E. Ber. Dtsch. Bot. Ges., 1974, 87: 267. [24] Rech M, Moucet J L, Manceau A M, et al. Botanica Marina, 2005, 48(5): 407. [25] Ruhland C T, Xiong F S, Clark W D, et al. Photochemistry and Photobiology, 2005, 81(5): 1086. [26] LIU Min, LI Rong-gui, FAN Hai, et al(刘 敏, 李荣贵, 范 海, 等). Acta Botanica Boreali-Occidentalia Sinica(西北植物学报), 2007, 27(2): 291. [27] SHI Sheng-bo, BEN Du-ying, ZHAO Xin-quan, et al(师生波, 贲杜英, 赵新全, 等). Chinese Journal of Plant Ecology(植物生态学报), 2001, 25(5): 520. [28] Billings, Mooney H A. Annual Review of Biochemisty, 1968, 43: 481. [29] ZHU Yu-an(朱玉安). Shannxi Journal of Agricultural Sciences(陕西农业科学), 2007, 4: 78. [30] WU Xing-chun, LIN Wen-xiong, HUANG Zhong-liang(吴杏春, 林文雄, 黄忠良). Acta Ecological Sinica(生态学报), 2007, 27(2): 554. [31] Fedina I, Hidema J, Velitchkova M, et al. Biologia Plantarum, 2010, 54, (3): 571. [32] FANG Yun-zhong, ZHENG Rong-liang(方允中, 郑荣梁). The Theory and Application of Free Radical Biology(自由基生物学的理论与应用). Beijing: Science Press(北京: 科学出版社), 2002. 295. [33] DONG Xin-chun, ZHAO Shi-jie, GUO Shan-shan, et al(董新纯, 赵世杰, 郭姗姗, 等). Journal of Shandong Agricultural University·Natural Science Edition(山东农业大学学报·自然科学版), 2006, 37(2): 157.