外源α-生育酚提高青绿苔草耐盐性生理机制的研究

发布时间：2018-08-27 12:41

【摘要】：土壤盐碱化会严重影响植物的生长发育,通过外源化学物质调控减少盐胁迫对植物的伤害,提高植物自身对盐碱环境的适应能力,对于促进盐胁迫下植物的正常生长发育以及盐碱地绿化具有重要意义。α-生育酚是绿色植物重要的脂溶性抗氧化剂之一,是植物在逆境下细胞膜上重要的效应物。本研究以青绿苔草(Carex leucochlora)为试验材料,研究不同浓度外源α-生育酚对盐(0.8%NaCl)胁迫下青绿苔草植株生长抑制及伤害的缓解作用;并在此基础上,研究了外源α-生育酚对盐胁迫下青绿苔草体内活性氧代谢、渗透调节以及光合代谢的影响。旨在揭示外源α-生育酚在提高青绿苔草耐盐性中发挥的主要生理调节功能,并为生产上增强植物的抗盐性提供一定的理论依据。本研究结果如下:1.适宜浓度的外源α-生育酚处理可以缓解盐胁迫对青绿苔草生长和质膜的伤害,并进一步提高其内源生育酚的含量。盐胁迫下青绿苔草的生长和质膜均受到伤害,且内源生育酚含量显著提高;0.2mM~1.0mMα-生育酚均能不同程度地增加盐胁迫下青绿苔草的株高和干物质的积累,降低丙二醛(MDA)含量和质膜相对透性,并且进一步提高其内源生育酚含量。其中以0.8mM的外源α-生育酚对盐胁迫伤害的缓解作用效果最佳,且在此浓度下青绿苔草内源生育酚含量最高。2.外源α-生育酚可以通过提高青绿苔草抗氧化酶活性以及改善抗坏血酸-谷胱甘肽循环来降低盐胁迫下植株体内过多活性氧的积累。盐胁迫下青绿苔草体内活性氧水平显著增加,抗氧化酶超氧化物歧化酶(SOD)、过氧化氧酶(CAT)活性以及非酶促抗氧化物质抗坏血酸(ASA)和谷胱甘肽(GSH)含量变化均呈先上升后下降的趋势,而ASA/DHA和GSH/GSSG比值均显著下降;外源喷施α-生育酚提高了盐胁迫下青绿苔草抗氧化酶SOD、过氧化物酶(POD)和CAT的活性,ASA和GSH含量增加,ASA/DHA和GSH/GSSG比值增大,同时植株体内抗坏血酸氧化酶(APX)、谷胱甘肽还原酶(GR)和脱氧抗坏血酸还原酶(DHAR)活性显著升高。这些结果说明,盐胁迫下α-生育酚不仅可以通过提高抗氧化酶活性来降低植株体内过多的活性氧,同时还可以调节抗坏血酸-谷胱甘肽循环中非酶促抗氧化物质的含量以及比例来加强活性氧的清除,从而缓解盐胁迫对青绿苔草植株的伤害作用。3.外源α-生育酚改善了盐胁迫下青绿苔草的渗透调节功能。在盐胁迫下,青绿苔草植株体内的K~+/Na~+、Ca~(2+)/Na~+下降;游离脯氨酸和可溶性糖含量均显著升高,可溶性蛋白含量呈先上升后下降的趋势。喷施α-生育酚显著提高了盐胁迫下青绿苔草植株体内K~+/Na~+、Ca~(2+)/Na~+值;游离脯氨酸含量和可溶性蛋白积累量与纯盐胁迫相比显著提高,可溶性糖含量无显著变化。说明α-生育酚可以通过调节青绿苔草植株体内的无机离子和有机渗透调节物质,使植物维持平衡的渗透压和离子比例。4.外源α-生育酚可以显著改善盐胁迫下青绿苔草的光合特性。盐胁迫下青绿苔草的叶绿素含量和气孔导度(Gs)显著下降,从而导致叶片净光合速率(Pn)下降;盐胁迫显著降低了青绿苔草的PSⅡ实际光化学效率(φPSⅡ)、光化学淬灭系数(qP)和PSⅡ最大潜在光化学效率(Fv/Fm)。外源喷施α-生育酚提高了青绿苔草的叶绿素b和类胡萝卜素含量,以及Gs、Pn、φPSⅡ和qP值,同时降低了胞间CO_2浓度(Ci)。说明在盐胁迫下,青绿苔草的叶绿素PSⅡ反应中心受到破坏,光合性能下降;外源α-生育酚可以通过增强光合电子传递效率,增加光化学反应分配的光能份额,从而提高实际光化学效率,增强青绿苔草植株的耐盐性。
[Abstract]:Soil salinization will seriously affect the growth and development of plants. Reducing the damage of plants under salt stress and improving the adaptability of plants to salt-alkali environment through the regulation of exogenous chemicals are of great significance to promote the normal growth and development of plants under salt stress and greening of saline-alkali land. In this study, Carex leucochlora was used to study the effects of different concentrations of exogenous alpha-tocopherol on growth inhibition and injury relief of Carex leucochlora under salt (0.8% NaCl) stress. The aim of this study is to reveal the main physiological regulation function of exogenous alpha-tocopherol in improving salt tolerance of Carex viridis under salt stress and to provide a theoretical basis for enhancing salt tolerance of plants in production. The results are as follows: 1. Tocopherol treatment could alleviate the damage to the growth and plasma membrane of Carex viridis under salt stress, and further increase the content of endogenous tocopherol. The content of malondialdehyde (MDA) and the relative permeability of plasma membrane decreased with the accumulation of high and dry matter, and the content of endogenous tocopherol increased further. Among them, 0.8mM exogenous alpha-tocopherol had the best mitigation effect on salt stress injury, and the content of endogenous tocopherol was the highest at this concentration. 2. Exogenous alpha-tocopherol could increase the content of endogenous tocopherol in Carex viridis. The activity of antioxidant enzymes and the improvement of ascorbic Acid-glutathione cycle in Carex viridis decreased the accumulation of excessive reactive oxygen species in plants under salt stress. The contents of ASA/DHA and GSH/GSSG increased first and then decreased, while the ratios of ASA/DHA and GSH/GSSG decreased significantly. Exogenous spraying of alpha-tocopherol increased the activities of SOD, POD and CAT, increased the contents of ASA and GSH, increased the ratios of ASA/DHA and GSH/GSSG, and increased the anti-scorbuting ability of the plants under salt stress. The activities of acid oxidase (APX), glutathione reductase (GR) and deoxyascorbate reductase (DHAR) were significantly increased. These results indicated that alpha-tocopherol could not only reduce the excessive reactive oxygen species in plants by increasing the activity of antioxidant enzymes, but also regulate the non-enzymatic antioxidants in the ascorbate-glutathione cycle under salt stress. The content and proportion of substance enhanced the scavenging of reactive oxygen species (ROS) and alleviated the damage of salt stress to Carex viridis. 3. Exogenous alpha-tocopherol improved the osmotic regulation of Carex viridis under salt stress. The content of soluble protein increased firstly and then decreased. Spraying alpha-tocopherol significantly increased K~+/Na~+, Ca~ (2+)/Na~+ values in Carex viridis plants under salt stress. Free proline content and soluble protein accumulation increased significantly compared with pure salt stress, but soluble sugar content did not change significantly. Over-regulation of inorganic ions and organic osmotic regulators in Carex viridis resulted in a balanced osmotic pressure and ion ratio. 4. Exogenous alpha-tocopherol could significantly improve the photosynthetic characteristics of Carex viridis under salt stress. Chlorophyll content and stomatal conductance (Gs) of Carex viridis significantly decreased under salt stress, resulting in a net leaf. Photosynthetic rate (Pn) decreased, salt stress significantly reduced PS II actual photochemical efficiency (phiPS II), photochemical quenching coefficient (qP) and PS II maximum potential photochemical efficiency (Fv/Fm). The concentration of O_2 (Ci) showed that the reaction center of chlorophyll PSII was destroyed and the photosynthetic performance was decreased under salt stress. Exogenous alpha-tocopherol could enhance the photosynthetic electron transfer efficiency and increase the share of light energy allocated by photochemical reaction, thereby improving the actual photochemical efficiency and enhancing the salt tolerance of the plant.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S688.4

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