增强UV-B辐射对植物的影响

综述了大气臭氧层的减少是影响地面UV-B辐射增强的主要因素,并进一步简述了增强UV-B辐射对陆生植物影响的最新研究进展。UV-B辐射一方面在分子水平上直接或间接地损害植物的DNA分子和蛋白质的结构,从而影响植物的各种生理生化过程影响;另一方面对植物的形态学特征(如叶表皮结构和花的形态结构等)产生广泛的影响。过强的UV-B辐射穿过叶表皮后直接对植物的光合系统、膜系统和植物生长调控激素等方面产生影响,从而会在植株个体、种群和生态系统等层次上表现出来。增强UV-B辐射作为全球变化因子,可导致敏感植物种类的死亡或退化,较能忍耐UV-B辐射的耐荫树种比阳生树种的适应性更强,能竞争到更多的利用资源,因此,在全球UV-B辐射增强下阳生树种可能会提早退出植物群落,这对森林群落的演替更新会起着重要的作用。文章还综述了UV-B辐射与其它污染胁迫因子和环境因子的复合作用共同对植物产生的影响,以及植物对UV-B辐射的防御和修复等防护对策,提出了今后要加强对生态系统的大尺度、长时间的宏观研究,以及开展增强UV-B辐射对地下生态学,对DNA的修复与表达机理,对植物信号接收和传导的新途径等方面的研究。

Effects of enhanced UV-B radiation on plants

Ozone depletion is the key factor influencing UV-B radiation reaching earth, and effects of enhanced UV-B radiation on plants and further on ecosystems has been reviewed in this paper. Enhanced UV-B radiation has pleiotropic effects on plant develop- ment, on morphology, and on physiology as well. On one hand enhanced UV-B radiation can directly and indirectly modify the DNA and protein structure, and thus change the physiological and biochemical processes. On the other hand UV-B radiation can impact leaf epidermis anatomical structure and flower morphological characters. High dose UV-B radiation can penetrate through leaf epi- dermis and thus may injure the photosynthetic system and Cell membrane, as well as phytohormone. The Morphological changes resulting from enhanced UV-B radiation may include reduced growth, thickened leaves and increased cuticular wax layers. In addi- tion, plant photosynthetic capacity, biomolecules, biomass, and eco-physiological characteristics of plants and ecosystems may also be influenced. In general, plants respond to enhanced UV-B radiation by stimulating their protection mechanisms or activating their repair mechanisms, such as phenolic compounds, flavonoids, and other biosynthesis of UV-B absorbing compounds. The joint effects of enhanced UV-B radiation and other abiotic factors on plants, and defending mechanisms of plants to enhanced UV-B radiation have also been summarized. In order to achieve further understanding on the mechanisms of interaction between enhanced UV-B radiation and plants, and to better prevent damages of UV-B radiation to plants and ecosystems, We suggested to conduct following studies in the future: 1) larger scale and long term filed research; 2) below-ground ecological research; 3) mechanisms of gene repair and expression; 4) plant signal generation and transduction; and 5) plant succession. As a global scale change factor, enhanced UV-B radiation could induce sensitive species to dead or degradation, however, tolerance trees species have more adaptability that could compete for more resources to keep dominant in ecosystems. In a sense, the sensitive species may accelerate degradation by en- hanced UV-B radiation, while tolerance species can keep dominant in ecosystems. Thus, enhanced UV-B may play an important role in plant community succession.