豆科树种根瘤和根瘤菌遗传多样性的研究

【作者】 李东；

【导师】 韩素芬；

【作者基本信息】 南京林业大学 ， 森林保护， 2011， 博士

【摘要】 多年来,豆科植物共生固氮研究多偏重于豆科作物、绿肥和牧草等,而对豆科树种研究起步较晚,直到二十世纪八十年代,固氮树种才引起人们更多的注意。开始着手于结瘤豆科树种调查和根瘤菌资源收集。根瘤菌侵入豆科植物形成共生根瘤才具有固氮能力。本文重点研究豆科树种根瘤的形态、结构和发育,同时对豆科树种根瘤菌遗传多样性及分类地位进行研究探讨。一、通过对刺槐根瘤发育过程中不同时期外部形态和结构的变化观察,在一级侧根上最先现瘤,逐渐向下延伸,呈现由上向下结瘤趋势。幼龄根瘤仅有一团分生组织,尔后分化形成根瘤原基,再发育为具有表皮、皮层、维管束和含菌细胞区完整的根瘤结构。发现根瘤细胞被根瘤菌侵染并充满多倍体细胞。顶端分生组织的数目与根瘤外部形态发育密切相关,单生根瘤仅含有一个顶端分生组织,’复生根瘤则有数个。二、通过对8种豆科树种根瘤的形态与结构研究,发现不同豆科树种的根瘤形态、大小、颜色各不相同,其结构与草本豆科植物类似,有皮层、维管束、含菌细胞区,也分为有限型根瘤和无限型根瘤二种类型。根瘤的结构类型与根瘤形状大小有一定的相关性。三、通过对53个豆科树种根瘤菌多态性的PCR-RFLP分析,豆科树种根瘤菌存在遗传多样性。但菌株的寄主和来源没有明显的相关性。与前人的研究对照在形态、生理生化特征和抗逆性等方面的研究有很大的相关性,但是不完全吻合。说明有着共同起源的菌株经过进化和环境的影响,其表型特征为了适应环境的变化而发生了相应的改变。四、通过对豆科树种根瘤菌株16S rDNA全序列分析,对其进行了系统进化树研究,取得一些研究结果,确定了大部分菌株的分类地位,为豆科树种根瘤菌研究提供理论依据,为开发和合理利用豆科树种根瘤菌种质资源奠定基础。更多还原

【Abstract】 For many years, the research on N(nitrogen)-fixation of Leguminosae sp. has paticularly addressed on Legume crops, green manure and forage grass. Until the 1980’s,the N-fixation of Leguminosae sp. began to draw wider attention and investigation on root nodules and germplasm collection of root nodule bacteria for woody Leguminosae plants were initialized.The root nodule bacteria penetrate into the Leguminosae plants to form symbiotic fixation. This paper mainly elaborated to study the morphological, structural and developmental characteristics of root nodule bacteria. Molecular markers were also employed to elucidate the genetic diversity and taxonomic system of root nodule bacteria from woody plants species.1. The outer morphology and structural changes at the different periods of growth of root nodules of Ribinia pseudoacacia were observed and it was found that the nucleus disappeared after the root nodule cells were infected with root nodule bacteria. The numbers of the meristem at the top are correlated to development of outer morphology of root nodules.2. The morphological and the structural characteristics of root nodules in 8 woody Leguminosae species were studied. It was found that root nodules varied in morphology, sizes and colors among the hosts. Their structure was similar to which had cortex, vascular bundle and bacteriocyte area. These root nodules could be divided into finite nodule and infinite nodule. The shape and size of nodules were correlated with nodule types.3. The polymorphophism of root nodule bacteria on 53 woody Leguminosae species were analyzed by PCR-RFLP. Clustering analysis revealed that the infected species were not correlated with the hosts and their area distribution. When compared with the previous studies, it was found that the morphology, properties of physiology and bio-chemistry and host resistance were somewhat correlated, but not identical, which implied that the same infected species being affected by evolutional and environmental factors, were sure to make corresponding changes in order to fit the environmental changes.4. Through 16SrDNA Sequence analysis on root nodules of infected woody Leguminosae species, their phylogenetic relationship was studied. Some conclusion were drawn based on the experimental data including the confirmation of taxonomic relationship of the most infected species, which provides the theoretical basis for the research on root nodule bacteria of woody Leguminosae species and lays the foundation on its development and rational utilization of the established root nodules germplasm.更多还原