【作者】 李梅；

【导师】 王一峰；

【作者基本信息】 西北师范大学 ， 植物学， 2013， 硕士

【摘要】 自1985年英国科学家在南极上空发现臭氧空洞以来，对臭氧层的破坏以及紫外辐射的增强越来越受到人们的关注。然而，近年来的研究表明青藏高原作为一个对全球大气问题极具敏感的地区其紫外辐射强度也在不断增加。它作为菊科风毛菊属植物的现代分布中心之一，分布于该地区的常见种风毛菊属植物必然会受到紫外线增强的影响。因此本文以分布于青藏高原东缘的三种常见风毛菊属植物，即长毛风毛菊（Saussurea hieracioides）、沙生风毛菊（Saussurea arenaria）及钝苞雪莲（瑞苓草（Saussurea nigrescens））为研究材料，运用统计分析研究其萌发特性并通过紫外分光光度法对生理生化指标的测定探讨该属植物对增强UV-B辐射胁迫的响应。本文测定的生理指标包括：叶绿素含量、丙二醛含量、过氧化氢含量、超氧阴离子自由基含量、可溶性糖含量、可溶性蛋白含量、紫外吸收物质含量，以及抗氧化酶活性即超氧化物歧化酶活性和过氧化氢酶活性。通过对实验数据的统计分析，探讨三种风毛菊属植物如何通过生理指标的变化响应增补UV-B辐射的胁迫处理并进行种间比较，以期为青藏高原东缘高寒草甸处于全球大气危机下的保护提供理论依据。对三种风毛菊属植物种子进行四个时间梯度（2、4、6、8小时）的UV-B辐射处理，并与未经辐射处理的种子萌发指标进行比较，结果表明：（1）三种风毛菊属植物种子经UV-B辐射处理后均出现萌发迟滞的现象，其萌发指数与未经辐射处理的对照组相比均出现显著降低，且UV-B辐射处理时间越长，萌发指数的降低越显著。（2）三种风毛菊属植物种子经UV-B辐射处理后萌发率均显著降低，其中长毛风毛菊（Saussurea hieracioides）种子萌发率随UV-B辐射处理时间增加而降低的曲线斜率最小，瑞苓草（Saussurea nigrescens）曲线斜率最大。对三种风毛菊属植物幼苗进行UV-B辐射处理，分别测定4个阶段（0、5、10、15天）UV-B辐射处理组与未处理的对照组幼苗的各项生理指标，结果表明：（1）在处理各阶段，三种风毛菊属植物幼苗中叶绿素a及叶绿素b含量均低于对照组，且随着处理时间的增加叶绿素a及叶绿素b含量逐渐降低，其中长毛风毛菊（Saussurea hieracioides）叶绿素a及叶绿素b含量随辐射时间增加而减小的曲线斜率均最小；类胡萝卜素含量则随辐射处理时间的增加而增加，长毛风毛菊（Saussurea hieracioides）类胡萝卜素含量随辐射时间增加而增加的曲线斜率最大。（2）随着UV-B辐射胁迫处理时间的增加，三种风毛菊属植物幼苗都受到一定的损伤，因此其丙二醛、过氧化氢及超氧阴离子自由基含量均出现不同程度的升高，其中长毛风毛菊（Saussurea hieracioides）丙二醛、过氧化氢及超氧阴离子自由基含量随辐射时间增加而增加的曲线斜率均最小。（3）为了对抗UV-B辐射造成的伤害，三种风毛菊属植物幼苗经过UV-B辐射胁迫后超氧化物歧化酶活性均有所增强，其中瑞苓草（Saussurea nigrescens）超氧化物歧化酶活性随辐射时间增加而增强的曲线斜率最小。除瑞苓草（Saussurea nigrescens）外，其他两种风毛菊属植物过氧化氢酶活性也随辐射时间的增加而增强。（4）三种风毛菊属植物幼苗经过UV-B辐射胁迫后可溶性糖含量均出现不同程度的增加，其中长毛风毛菊（Saussurea hieracioides）可溶性糖含量随辐射时间增加而升高的曲线斜率最大。除瑞苓草（Saussurea nigrescens）外，其他两种风毛菊属植物可溶性蛋白含量也随辐射时间的增加而升高。（5）随着UV-B辐射处理时间的增加，长毛风毛菊（Saussurea hieracioides）紫外吸收物质的含量与对照组相比变化不显著。其他两种风毛菊属植物幼苗中紫外吸收物质含量均有所增加，其中沙生风毛菊（Saussurea arenaria）紫外吸收物质含量随辐射时间增加而增长的曲线斜率大于瑞苓草（Saussurea nigrescens）。由以上实验结果可以看出，长毛风毛菊（Saussurea hieracioides）及沙生风毛菊（Saussurea arenaria）抵抗增补UV-B辐射造成胁迫损伤的能力强于瑞苓草（Saussurea nigrescens）。更多还原

【Abstract】 Since1984, when the British scientists found the ozone hole over the Antarctica, the destruction of ozonosphere and increase of UV irradiation has attracted many scientists and acquired lots of attentions. While, recent studies show that the Qinghai-Tibet Plateau as a highly sensitive areas of the global atmospheric crisis, its UV radiation intensity is also increasing. The Qinghai-Tibetan plateau is also one of modern distributive centers of the genus of Saussurea of Compositae, Saussurea distributing in this area as a common species will inevitably under the influence of ultraciolet enhancement. In this study, an experiment using by ultraviolet spectrophotometry was conducted to investigated the effects of UV-B irradiation on germination and physiological characteristics in three Saussurea species distribute in eastern Qinghai-Tibetan plateau, S. hieracioides Hook. f., S. arenaria Maxim. and S. nigrescens Maxim. The physiological indexes including chlorophy content, MDA content, hdrogen peroxide （H2O2） content, superoxide anion （·O₂^-） content, soluble sugar content, soluble protein content, UV-B-absorbing compounds content and antionxidant enzyme activity such as superoxide dismutase （SOD） and catlase （CAT） acticity. Through the statistical analysis of experimental data of response about three Saussurea under excess UV-B irradiation stress provides information for protection of alpine meadow under the background of global atmospheric crisis over the eastern of Qinghai-Tibetan Plateau.Three Saussurea species seeds treated with different UV-B radiation （2,4,6,8hours） compared with that without radiation processing, the results show that:（1） Three Saussurea seeds germination appeared hysteretic phenomenon under UV-B radiation treatment, and compared with the without radiation treatment control group the germination index showed a significant reduction beside with the increase of the duration of action, the germination index decline gradually.（2） Three Saussurea species seed germination was reduced significantly under UV-B radiation treatment, the slope of the curve that S. nigrescens seed germination decreased with the UV-B radiation processing time was the smallest.The physiological characteristic of three Saussurea species seedlings under UV-B radiation treatment and the untreated control seedlings were measured in four stages （0,5,10,15day）, the results showed that:（1） The content of chlorophyll a and chlorophyll b in three Saussurea seedling were lower than the control group in various stages of processing, and the content of chlorophyll a and chlorophyll b decreased with the increased processing time, the slope of the curve that S. hieracioides chlorophyll a and chlorophyll b decreased with the radiation time was minimum the content of carotenoid in three Saussurea seedling increased with radiation processing time, the slope of the curve S. hieracioides carotenoid content increased with the irradiation time was maximum.（2） Since the UV-B radiation processing time increased three Saussurea species seedlings were damaged, the content of MDA, H2O2and O-2were increased With the increase of the irradiation time, the slope of the curve that S. hieracioides MDA, H2O2and O-2content increased was minimum.（3） Counter with the damage caused by UV-B radiation, the SOD activity of three Saussurea seedlings were enhanced after UV-B radiation treatment, the slope of the curve that S. nigrescens SOD activity increased with the irradiation time was minimum. In addition to S. nigrescens, the other two species of Saussurea catalase activity were enhanced with the increase of the irradiation time.（4） The content of soluble sugar in three Saussurea species seedlings under UV-B radiation stress increased, of which the slope of the curve that S. hieracioides soluble sugar content increased with the irradiation time was maximum. In addition to S. nigrescens, the other two species of Saussurea soluble protein content increased with increasing irradiation time.（5） Compared to the control group the content of UV-absorbing compounds in S. hieracioides did not change significantly with the increase of UV-B irradiation treatment time. The slope of the curve that S. arenaria UV-absorbing compounds content increased with irradiation time was greater than S. nigrescens’s.The above experimental results showed that the ability to resistance UV-B irradiation damage of S. hieracioides and S. arenaria is stronger than S. nigrescens.更多还原