褪黑素处理对氯化钠胁迫下黄瓜种子萌发的影响及其分子机制

发布时间：2018-01-09 01:20

  本文关键词：褪黑素处理对氯化钠胁迫下黄瓜种子萌发的影响及其分子机制　出处：《中国农业大学》2016年博士论文　论文类型：学位论文

  更多相关文章： 黄瓜 种子萌发 氯化钠胁迫 褪黑素 植物激素 能量代谢

【摘要】：种子萌发是高等植物生命周期中一个非常复杂和关键的生物学过程,它影响植物的形态建成和生长发育。种子萌发起始于水分吸收,终止于胚根突破种皮露白。当种子吸水后,种子内部开始发生相应的生理生化反应打破休眠,启动萌发。种子萌发过程中包含蛋白质的合成,转录翻译后修饰,激素的合成与代谢等许多生理生化过程。褪黑素,化学名称为N-乙酰基-5-甲氧基色胺。褪黑素在植物中也是普遍存在的,但其在植物中的功能研究尚在起步阶段。植物除了从环境中吸收褪黑素以外还可以自身合成褪黑素。外源褪黑素处理能够提高植物对逆境胁迫的抵御能力。本论文探索了氯化钠胁迫下外源褪黑素处理对促进黄瓜种子萌发生理生化变化的影响,同时结合label-free技术从蛋白质组学的调控角度研究了褪黑素调控种子萌发的分子机制,使褪黑素在种子萌发过程中的作用更加清晰。主要结果如下：(1)外源褪黑素(1μmol/L)处理能够明显促进氯化钠胁迫下黄瓜种子萌发。氯化钠胁迫(150mmol/L)下,黄瓜种子中产生大量活性氧(ROS),羟自由基和过氧化氢都处于较高水平。褪黑素本身是一种抗氧化剂,因此,褪黑素处理能够清除氯化钠胁迫产生的多余活性氧,使羟自由基和过氧化氢的含量处于较低水平,膜脂过氧化程度下降,从而保护细胞免于氧化伤害。同时作为一种调控因子,褪黑素通过促进种子内抗氧化酶合成基因CsCu-ZnSOD, CsFe-ZnSOD, CsCAT和CsPOD的表达来提高超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的活性,促进多余活性氧的清除,从而保持体内活性氧平衡。(2)ABA和GA的合成代谢对种子萌发的影响非常重要。外源褪黑素能够促进氯化钠胁迫下黄瓜种子萌发过程中ABA的分解代谢和GA的合成。在氯化钠胁迫下,一方面褪黑素通过上调ABA代谢基因CsCYP707A1和CsCYP707A2的表达加速ABA的代谢分解；同时下调ABA的合成基因CsNECD2的表达阻碍ABA的生物合成,使得种子萌发过程中ABA含量迅速下降,解除ABA对种子萌发的抑制作用。另一方面,褪黑素还能上调GA合成基因CsGA20ox和CsGA3ox的表达,使种子内GA尤其是HA4的合成增加,缓解氯化钠胁迫对种子萌发的抑制作用。(3)氯化钠胁迫下,褪黑素显著促进了种子内贮藏物质(球蛋白)代谢和细胞骨架(微管和微丝蛋白)的生成,促进细胞分裂和伸长,进而促进种子萌发。褪黑素还调控众多与信号传导和逆境胁迫相关蛋白,包括14-3-3蛋白,HSP,抗氧化系统酶,泛醌溶酶体蛋白等。以上结果说明,褪黑素能够调控萌发过程中种子对氯化钠胁迫下信号的感知,多余活性氧的清除,胁迫的耐受性和受损蛋白的重新折叠及降解等过程。(4)蛋白质组学数据表明,外源褪黑素能够参与种子萌发过程中能量的代谢调控。氯化钠胁迫下,褪黑素处理加速种子中油脂的降解,降解产物脂肪酸进入乙醛酸循环。褪黑素显著上调乙醛酸循环中关键酶异柠檬酸裂解酶和苹果酸合酶的活性,从而调控乙醛酸循环。褪黑素还能够提高α,β-淀粉酶的活性来加速淀粉的降解。褪黑素还调控产生大量ATP的糖酵解和三羧酸循环通路。结果表明,褪黑素上调代谢通路上9个相关酶的表达来调节能量的代谢,最终为种子萌发提供能量支持。以上研究结果表明,褪黑素能够通过促进氯化钠胁迫下黄瓜种子中能量的合成来促进种子萌发。
[Abstract]:Seed germination is a very complex and critical biological processes in the life cycle of higher plants, it affects the completion and plant growth form. Seed germination starting on moisture absorption, terminating in the seed coat. When white radicle seeds after absorbing water, seed physiological and biochemical reaction within the corresponding break dormancy and germination. Contains a start protein synthesis during seed germination, transcription and post-translational modification, many physiological and biochemical processes of hormone synthesis and metabolism. Melatonin, the chemical name is N- acetyl -5- methoxytryptamine. Melatonin is widespread in plants, but their functions in plants research is still in the initial stage. In addition to the absorption of melatonin in plants from the outside environment can also synthesize melatonin. Exogenous melatonin treatment can improve the resistance of plants to adversity stress. This paper explores the NaCl stress. Under the influence of exogenous melatonin treatment on physiological and biochemical changes to promote germination of cucumber seeds, combined with label-free technology from the perspective of the regulation of proteomics to study the molecular mechanisms of melatonin in the regulation of seed germination, the melatonin during seed germination is more clear. The main results are as follows: (1) exogenous melatonin (1 mol/L) treatment stress could promote the germination of Cucumber Seeds under NaCl stress. Sodium chloride (150mmol/L), ROS in cucumber seeds (ROS), hydroxyl radicals and hydrogen peroxide are at a high level. Melatonin is an antioxidant, therefore, melatonin treatment can excess reactive oxygen scavenging sodium chloride stress generated by the the content of hydroxyl radicals and hydrogen peroxide in the low level, the degree of membrane lipid peroxidation decreased, thereby protecting cells from oxidative damage. At the same time as a control factor, fade Melanin by promoting seed antioxidant enzyme synthesis genes CsCu-ZnSOD, CsFe-ZnSOD, CsCAT and CsPOD to improve the expression of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activity, promote the removal of excess reactive oxygen species, so as to maintain the balance of active oxygen in the body. (2) synthesis and metabolism ABA and GA are very important effects on seed germination. Exogenous melatonin can promote metabolism and GA synthesis and decomposition of sodium chloride stress on cucumber seed germination process in ABA. Under NaCl stress, on the one hand, melatonin through upregulation of ABA metabolism genes CsCYP707A1 and CsCYP707A2 accelerate the metabolism of ABA decomposition; biosynthesis of synthetic gene expression CsNECD2 at the same time, the down-regulation of ABA block ABA, ABA content decreased rapidly the seed germination process, relieve the inhibition of ABA on seed germination. On the other hand, melatonin can up regulate GA synthesis The expression of CsGA20ox and CsGA3ox, the seed of GA especially the increased synthesis of HA4, ease of NaCl stress on seed germination. (3) under NaCl stress, melatonin significantly promoted the substance in seeds (globulin) metabolism and cytoskeleton (microtubule and microfilament formation, promote cell protein) division and elongation, and promote seed germination. Melatonin also regulates many related proteins and signal transduction and stress, including 14-3-3 protein, HSP, antioxidant enzyme system, ubiquinone lysosomal protein. These results indicated that the seed germination process in the regulation of melatonin to stress signal perception of sodium chloride, remove excess reactive oxygen species. Stress tolerance and impaired protein refolding and degradation process. (4) proteomics data show that exogenous melatonin can participate in energy metabolism during seed germination of sodium chloride. Under the stress of accelerated degradation in the seed oil of melatonin treatment, the degradation products of fatty acids into the glyoxylate cycle. Melatonin significantly increased ethylene acid cycle enzymes isocitrate lyase and malate synthase activity, thereby regulating the glyoxylate cycle. Melatonin can improve the degradation of alpha, beta amylase activity to accelerate starch the regulation of melatonin. Also produced a large number of ATP of glycolysis and the tricarboxylic acid cycle three pathway. The results showed that the expression of the 9 enzymes related to the metabolism of melatonin increases metabolic pathways to regulate energy, to provide energy support for the final germination of seeds. The above results showed that melatonin could promote the synthesis of Cucumber Seeds under NaCl stress in energy to promote the seed germination.

【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】：S642.2
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本文编号：1399443