光谱学与光谱分析, 2016, 36 (5): 1389, 网络出版: 2016-12-20
增强的UV-B辐射对高粱幼苗光合和抗氧化系统的影响
Effects of Enhanced Ultraviolet B Irradiation on Photosynthetic and Antioxidant System of Sorghum Seedlings
摘要
由于臭氧层逐渐变薄, 到达地球表面UV-B辐射不断增加, 因UV-B辐射改变的太阳光谱将会对陆地植物造成不同程度的伤害。 本试验以高粱龙杂5为材料, 对二叶一心高粱进行四种剂量UV-B处理, 恢复2 d采用光合仪测定光合参数, 并取样测定抗氧化酶活性。 随着UV-B剂量的升高, 高粱叶片褐化损伤加重, 植株矮化, 鲜重和干重显著降低; 花青素含量显著升高, 叶绿素和类胡萝卜素含量显著减少, 净光合速率和叶绿素荧光参数显著下降。 同时, 随UV-B剂量升高, 高粱幼苗气孔导度、 胞间CO2浓度和蒸腾速率表现为“降-升-降”变化; POD和CAT活性呈现“降-升-降”变化; SOD和GR活性呈现“降-升”变化, APX和GPX呈现“升-降-升”变化。 在供试的四种剂量中, UV-B处理6 h(相当2.4 J·m-2)的高粱幼苗净光合急剧下降, 其他光合指标以及抗氧化酶活性也表现出明显转折。 结果表明, 增强的UV-B辐射直接导致高粱光合色素、 净光合速率和叶绿素荧光参数的改变; 高粱抗氧化系统对高、 低剂量UV-B响应机制不同, 其中 ASA-GSH循环对低剂量UV-B反应更敏感, 高剂量UV-B辐射不仅破坏高粱光合作用, 而且启动植物酶促和非酶抗氧化系统, 导致叶片褐化坏死, 植株生物量累积减少、 株高矮化, 甚至死亡。
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.
石新新, 李佐同, 杨克军, 赵长江, 杨荣斌, 于高波, 黄寿光, 徐晶宇, 贺琳, 赵莹, 许艳梅, 马丽峰, 范博文. 增强的UV-B辐射对高粱幼苗光合和抗氧化系统的影响[J]. 光谱学与光谱分析, 2016, 36(5): 1389. SHI Xin-xin, LI Zuo-tong, YANG Ke-jun, ZHAO Chang-jiang, YANG Rong-bin, YU Gao-bo, HUANG Shou-guang, XU Jing-yu, HE Lin, ZHAO Ying, XU Yan-mei, MA Li-feng, FAN Bo-wen. Effects of Enhanced Ultraviolet B Irradiation on Photosynthetic and Antioxidant System of Sorghum Seedlings[J]. Spectroscopy and Spectral Analysis, 2016, 36(5): 1389.