硅诱导大豆幼苗抗UV-B辐射的研究

发布时间：2018-05-26 05:31

本文选题：大豆 + 硅　；参考：《中国农业大学》2016年博士论文

【摘要】：由臭氧层损耗引起的UV-B辐射增强会对植物产生一系列不利影响,硅营养能够提高植物对UV-B辐射胁迫的抗性,但其作用机理尚不清楚。本研究以双子叶作物大豆(Glycine max (L.)Mell)为试验材料,在人工气候室条件下,采用营养液培养方式,研究了硅(K2Si03· nH2O,1.70 mM)营养对UV-B辐射增强胁迫(5.4Kj m-2 d-1)下大豆幼苗形态变化、初生代谢物质和次生代谢物含量、植物内源激素水平、叶片蛋白质表达量以及DNA损伤情况的影响。旨在阐明硅在提高植物对UV-B辐射的防护、修复功能中的生物学效应及其机理。主要结果如下：1.W-B辐射增强对大豆幼苗形态的影响包括：引起叶片细胞死亡加剧,叶片卷缩,叶面积减小；使总根长变短,根系平均直径、根体积和表面积均变小；改变干物质在地上部与地下部之间的分配,减少干物质积累量。硅预处理能有效缓解UV-B辐射胁迫对幼苗的影响,表现为：减轻叶片的细胞死亡和卷曲程度,抑制根系总根长、表面积和体积的减小,减轻对植株生长的抑制,降低生物量的减少幅度。2.UV-B辐射胁迫下,大豆幼苗叶片的内源激素IAA含量降低,ABA和ETH含量升高,IAA/ABA比值降低；硅预处理能抑制UV-B辐射引起的IAA含量下降,并降低ABA和ETH含量,使IAA/ABA比值上升。UV-B辐射胁迫降低可溶性糖和可溶性蛋白的含量,增加游离氨基酸的含量；硅预处理则能缓解可溶性糖和可溶性蛋白含量的降低,并降低游离氨基酸的含量。UV-B辐射胁迫诱导苯丙氨酸解氨酶PAL的活性增强,促进次生代谢物质蜡质、UV-B吸收物质、酚类物质和类黄酮合成的增加,提高大豆幼苗对辐射胁迫的被动适应能力；硅预处理能进一步促进PAL酶活性的增加,提高叶片内蜡质、酚类物质和类黄酮的含量,增强植株对辐射胁迫的抗性。3.UV-B辐射胁迫下,硅预处理能够通过调节相关蛋白表达使大豆幼苗更好地适应环境,这些调控涉及到代谢/能量、次级代谢、防御系统、抗氧化系统、激素合成等方面。UV-B辐射胁迫通过调控分子信号物质乙烯和ROS诱导病原相关蛋白(PR)的积累,使得植物获得系统抗性。硅预处理能够显著提高幼苗的广谱抗病性,并改善植物的光合作用和次生代谢。4.UV-B辐射胁迫诱导大豆幼苗叶片中CPDs的形成和积累,而直接的氧化胁迫并不能诱导CPDs的形成,即DNA的光化产物CPDs只能通过UV-B胁迫的直接辐射诱导形成。大豆叶片中CPDs的修复以光修复为主。硅预处理能够减少CPDs的形成、通过促进光修复作用,提高DNA损伤的修复能力、减少CPDs的积累。硅预处理可通过以下机制减轻UV-B辐射对DNA的伤害：1)修复机制,光裂合酶主导的修复作用；2)避免机制,紫外吸收物质介导的表皮屏蔽作用；3)抗氧化机制,诱导抗氧化物质合成的增加,如抗坏血酸等。
[Abstract]:The increase of UV-B radiation caused by ozone layer loss will have a series of adverse effects on plants. Silicon nutrition can increase the resistance of plants to UV-B radiation stress, but its mechanism is not clear. Using Glycine max L.Mell. a dicotyledonous crop as experimental material, the morphological changes of soybean seedlings under UV-B radiation enhanced stress (5.4Kj m-2 路d-1) were studied under the condition of artificial climate room and nutrient solution culture. Effects of primary and secondary metabolites, endogenous hormones, protein expression in leaves and DNA damage. The aim of this paper is to elucidate the biological effects and mechanism of silicon in the protection and repair of UV-B radiation in plants. The main results were as follows: 1. The effects of W B radiation on the morphology of soybean seedlings were as follows: the death of leaf cells was aggravated, the leaf was curled and the leaf area was decreased, the total root length was shortened, the mean diameter of root system, root volume and surface area were decreased; To change the distribution of dry matter between the aboveground and underground parts and reduce the dry matter accumulation. Silicon pretreatment could effectively alleviate the effects of UV-B radiation stress on seedlings, such as reducing the cell death and curl degree of leaves, inhibiting the decrease of root total root length, surface area and volume, and reducing plant growth. Under UV-B radiation stress, the contents of endogenous hormones IAA and ETH in soybean seedling leaves increased and the ratio of IAA / ABA decreased, silicon pretreatment inhibited the decrease of IAA content induced by UV-B radiation, and decreased the contents of ABA and ETH. The ratio of IAA/ABA increased. UV-B radiation stress decreased the content of soluble sugar and soluble protein, increased the content of free amino acid, and reduced the content of soluble sugar and soluble protein after silicon pretreatment. The activity of phenylalanine ammonia-lyase PAL was enhanced under UV-B radiation stress, and the synthesis of secondary metabolite, waxy substance, phenolic substance and flavonoid was increased, and the activity of phenylalanine ammonia-lyase (PAL) was increased under UV-B radiation stress. Silicon pretreatment could further increase the activity of PAL, increase the contents of wax, phenols and flavonoids in leaves, and enhance the resistance of soybean seedlings to radiation stress. 3. UV-B radiation stress, silicon pretreatment could increase the activity of PAL, increase the contents of wax, phenols and flavonoids in leaves, and enhance the resistance of soybean seedlings to radiation stress. 3. Silicon pretreatment can improve the adaptation of soybean seedlings to the environment by regulating the expression of related proteins, which involves metabolism / energy, secondary metabolism, defense system, antioxidant system, In hormone synthesis, UV-B radiation stress induced phylogenetic resistance by regulating the accumulation of molecular signaling substances ethylene and ROS. Silicon pretreatment could significantly improve broad-spectrum disease resistance, photosynthesis and secondary metabolism. 4. UV-B radiation stress induced the formation and accumulation of CPDs in soybean seedling leaves, but direct oxidative stress could not induce the formation of CPDs. That is, CPDs, the photochemical product of DNA, can only be induced by direct radiation under UV-B stress. The repair of CPDs in soybean leaves was mainly light repair. Silicon pretreatment can reduce the formation of CPDs, improve the repair ability of DNA damage and reduce the accumulation of CPDs by promoting photorepair. Silicon pretreatment can alleviate the damage of UV-B radiation to DNA by the following mechanisms: 1) repair mechanism, 2) avoidance mechanism of photolysis synthase, and 3) antioxidation mechanism of ultraviolet absorbent substance mediated epidermal shielding. Induces an increase in the synthesis of antioxidants, such as ascorbic acid.
【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S565.1

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