高温干旱胁迫中植物膜脂分子变化--兼滑桃树内生菌次生代谢产物研究 
郁步竹 
学位类型博士
导师李唯奇 
2010-11
学位授予单位中国科学院研究生院
学位专业植物学
摘要细胞膜系统不仅仅能够把细胞与外界环境分隔开,而且还是细胞内各种生化反应得以有序进行的基础,因此对植物的生存起着非常重要的作用,尤其是在外界环境的胁迫下。在所有的外界环境因素中,温度胁迫与组成细胞膜的膜脂关系最为紧密,研究的也最为深入,但是以往的研究主要集中在膜脂脂肪酸组成与植物抗低温胁迫的关系上。相对而言,研究高温下植物膜脂分子组成的变化与植物抗高温胁迫的关系较少而且也不够深入和全面。如今,随着温室气体的大量排放,全球的气温日益升高,高温对植物生长尤其是作物的生产影响越来越明显。因此研究植物在高温下的膜脂分子组成的变化以及膜脂与高温胁迫之间的关系也就显得越发的急迫。本论文中我们主要选择拟南芥(Arabidopsis thaliana)及其热敏感突变体(hot-1)为研究对象,运用电喷雾串联质谱联用 (ESI-MS/MS)的方法研究不同高温胁迫处理过程中膜脂分子的变化规律。热胁迫过程包括了高温胁迫和长期的中高温胁迫。其中,高温胁迫处理一般分为两种:直接热激和热驯后热激,直接热激指直接将拟南芥放在高温下(45°C)处理;热驯后热激指在适当温度(38°C)的驯化处理后进行热激。而长期的中高温胁迫是指在一个不导致拟南芥致死的中高温下(30°C)长期的热处理。实验得到下列结果:第一:在高温胁迫和长期的中高温胁迫过程中膜脂的变化是截然不同的两种模式:在长期的中高温胁迫过程中膜脂的降解是有选择性的,主要减少的是叶绿体膜中含有多不饱和脂肪酸的膜脂分子;而在高温热胁迫下,膜脂的降解是没有选择性的,无论是质膜还是叶绿体膜都是同样的降解速度。第二:发现高温胁迫过程中,热激前进行适当温度的热驯处理可以显著的减慢膜脂的降解速度,且膜脂降解速度变慢与热激蛋白HSP101无关。说明热驯过程除了与热激蛋白HSP101的积累有关,与膜脂的锻炼也有很重要的关系。第三:发现了磷脂酸变化与植物耐热性之间的辩证关系。当磷脂酸适度的升高时,可以提高植物的抗高温能力,而当磷脂酸升高超过了一定的范围后反而会破坏膜的结构,导致植物死亡。第四:HSP101蛋白在长期中高温胁迫过程中可以改变植物膜脂脂肪酸不饱和度和膜脂分子的组成。长期的中高温胁迫过程影响了突变体不饱和脂肪酸和脂肪酸的组成,同时导致了PS分子的积累。论文还包括另外两方面的研究。一是小盐芥的抗干旱胁迫研究;二是滑桃树内生菌次生代谢产物的化学及生物学活性研究。小盐芥(Thellungiella halophila)为十字花科盐芥属植物,同模式植物拟南芥非常相似,它也具有植株矮小、生长周期短、种子量大、基因组小等特点。前期的研究表明其在cDNA水平上和拟南芥有94%的相似性,并且具有很强的抗逆能力,因此近年来被用来作为研究抗逆的模式植物。以往的研究较多涉及的是小盐芥抗盐胁迫方面的研究,对于其抗干旱的研究非常少,且研究小盐芥膜脂与干旱胁迫之间的关系几乎就是一个空白,而干旱目前也是限制农业发展的一个重要因素。因此本论文主要集中研究小盐芥在干旱胁迫下的生理和膜脂变化,得到以下结果:第一:小盐芥具有较好的保持水分能力。与其在正常状态就可以积累渗透调节物质和对ABA的快速响应有关。第二:小盐芥具有较强的抑制和消除氧化胁迫的能力。第三:干旱导致了拟南芥叶绿体膜脂的快速降解,但对小盐芥却没有影响。说明小盐芥能够在干旱的条件下更能维持植物叶绿体膜的稳定结构。植物内生菌由于其种类多,代谢途径复杂,以及与宿主之间的协同进化,近年来从内生菌中寻找天然的具有活性的化合物越来越成为研究的热点。本论文对热带植物滑桃树进行研究,从中共分离得到内生菌46株。并对其中的34株内生真菌进行发酵测试其提取物的抗病原菌活性,其中有活性的菌株达到17株,占了50%。并从6株内生菌的发酵产物中分离得到化合物24个,其中得到解析的化合物22个,包括大环内酯,azaphilone,蒽醌,甾体等结构,已鉴定的化合物有8个为新化合物。从上述结果我们可以知道,滑桃树的内生菌具有丰富的多样性,其代谢产物具有丰富的生物活性和丰富的化学结构类型,为寻求结构新颖具有活性的化合物提供了巨大的资源条件。
资助项目The membrane system of cell performs many important functions, such as separates cells from the environment, keeps the biochemical reactions in order ect.. The integrity of membrane is very important for plants to survive, especially under the environmental stress. Among all environmental factors, temperature has the closest relationship with membrane and intensively study on this area has been reported. Most researches are mainly focused on the relationship between the composition of fatty acid about membrane and low temperature, while that with high temperature are rare. Nowadays, the increasing concentration of CO2 resulted in increasing temperature and high temperature has become an important inhibition to crop productivity. Thus, it’s necessary and emergent to study the relationship between membrane lipids and high temperature.In the present dissertation, Arabidopsis and its high temperature sensitive mutant were chosen to study the relationship between membrane lipids and high temperature. The ESI-MS/MS was used to examine the composition of membrane lipids. High temperature includes two categories, one is heat stress and the other is moderate heat stress. Heat stress can be divided into two processes: with and without heat acclimation. Five results have been obtained grounding on these works. Firstly, different change models of membrane lipids during heat stress and moderate stress had been found. The degradation of membrane lipids during moderate heat stress was controlled, while that of heat stress was out of control. During moderate heat stress, the degradation mainly happened on chloroplast, such as DGDG and PG, especially those lipids which has polyunsaturated fatty acids. Under heat stress, the degradation about plasma membrane and chloroplast membrane shared same rates. Secondly, the degradation of membrane lipids was reduced when plants had experienced heat acclimation before heat stress, and this change had nothing to do with accumulation of HSP101. The results suggested the acquired thermo-tolerance not only had related with HSP101, but also with membrane lipids. Thirdly, the amount of phosphatidic acid (PA) played an important role during heat stress. If the amount of PA rose to proper extent, it benefited the plants, while if it rose to high level, it destroyed the membrane structure. At last, the HSP101 mutant had higher ratio of polyunsaturated fatty acids/ saturated fatty acids than that of wild Arabidopsis under long term moderate heat stress. The dissertation also included other two parts: the drought-tolerance of Thellungiella halophila and the chemical structure and bioactivity of the second metabolites from endophytes, which were isolated from Trewia nudiflor. Thellungiella halophila shared the same characteristic with Arabidopsis in many aspects, such as dwarf phenotype, short life cycle, fertility and small genome. The research indicated that at cDNA level, they were also very similar. Besides these Thellungiella halophila was more tolerant to stress condition. The previous research about Thellungiella halophila mainly focused on the high-salinity stress, and the researches of drought stress were rare. In this dissertation we focused on the drought-resistance of Thellungiella halophila. Compare to Arabidopsis, Thellungiella halophila could keep water content in high level, more resist to ROS, good photosynthesis activity and keep the membrane system integrity under drought stress. It was interesting that the substances, which rose when Arabidopsis under stress, were at high level in normal Thellungiella halophila, such as: proline, ABA. The degradation of membrane lipids mainly happened on chloroplast membrane of Arabidopsis. In contrast, the membrane of Thellungiella halophila didn’t change. All these evidence indicated that Thellungiella halophila was more drought-tolerant than Arabidopsis. During the research about the chemical structure and bioactivity of the second metabolites from endophytes, which were isolated from Trewia nudiflor, we isolated 46 endophytes from different parts of plants . 34 species of them were selected for bioactivity test, and the bioactivity test show that 50% of them have some bioactivity. We also isolated 24 compounds from 6 endophytes, and 22 of them have been identified by spectra data, including: macrolides, azaphilones, anthraquinones, and steroids. 8 of them are novel compounds. Judging from results, we know the Trewia nudiflor is good resources to isolate endophytes and the endophytes are good resources to search for novel and bioactivity compounds.
语种中文
文献类型学位论文
条目标识符http://ir.kib.ac.cn/handle/151853/16032
专题昆明植物所硕博研究生毕业学位论文
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郁步竹 . 高温干旱胁迫中植物膜脂分子变化--兼滑桃树内生菌次生代谢产物研究 [D]. 中国科学院研究生院,2010.
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