中国云南西北地区杜鹃花菌根的多样性研究
田伟
学位类型博士
导师张长芹
2010-01
学位授予单位中国科学院研究生院
学位专业植物学
摘要滇西北是现代杜鹃花的分化中心之一,本地区杜鹃花物种丰富,在生态系统中扮演着重要角色。杜鹃类菌根在植物适应环境、增强抗逆性以及养分吸收等方面发挥了重要作用。本文调查了滇西北27种杜鹃花的生境,对17种杜鹃花根系进行了切片观察,选取了R. decorum(三个居群)、R. pachypodum和R. phaeochrysum三种杜鹃花,每个居群各取100个根段分离和培养菌根菌,结合菌落的形态特征和ITS rDNA的序列重点鉴定大白花杜鹃的菌根菌,对菌的种类多样性进行了比较并分析了三个居群菌根菌的种类多样性和分布;并对菌根菌对大白花杜鹃生长发育的影响进行了初步研究。主要结论如下:1. 杜鹃花生境调查:我们调查的43个居群的27种杜鹃花野外居群海拔从2500m至4650m。植被调查和土壤pH测试结果表明:杜鹃花多生长于高山针叶林及常绿阔叶与落叶阔叶混交林,土壤pH为5.4-6.9。2. 根系切片:17种杜鹃花根系切片观察结果:表层细胞中都形成杜鹃类菌根结构,其中19个居群的8种杜鹃花根部菌丝有锁状联合,部分存在深色有隔真菌菌丝,说明有担子菌和子囊菌并存。3. 菌落培养特征:从3种杜鹃花(大白花杜鹃、粗柄杜鹃和褐黄杜鹃)的500个根系中分离培养了近400个生长缓慢的菌落,各菌落形态特征差别很大,质地、边缘颜色、分泌液滴、分生孢子、生长速度、出现频率等差别较大。各菌落出现的次数不仅在不同居群不同杜鹃根系中很不平衡,即使在同种不同居群内差别也很大,褐黄杜鹃和其他居群其他种共有的菌较少。4. 大白花杜鹃菌根菌多样性研究: 对两个野生居群和一个人工居群的大白花杜鹃300个根段进行分离和培养,选出218个生长缓慢的菌株,根据形态特征进行归类,其中125个菌属于杜鹃类菌根菌,然后将20份代表菌进行ITS rDNA测序并鉴定。结合形态解剖及分子学证据,鉴定为子囊菌门的12个种,其中9种分别属于盘菌亚门Pezizomycotina中的4个目9个属中,另外三个菌未鉴定出来。大白花杜鹃3个居群的菌根菌种类分别为11,8和8,其中7个为共有种。在12种杜鹃类菌根菌中,4个种属于柔膜菌目Helotiales,是云南杜鹃花属植物菌根菌的主要组成成分。Oidiodendron maius占大白花杜鹃菌根菌总数的18.4%,也是优势种之一,但是它在大白花杜鹃三个居群中的分布不平衡,在野外居群中分别占21.1%和27.1% ,在人工居群中仅占5.1%。其它菌根菌如:Neonectria radicicola等在前人的研究中未见报道。Simpson指数和Shannon-Weiner指数显示野外居群的大白花杜鹃菌根菌种类多样性比人工居群的高。5. 菌根菌对大白花杜鹃的初步影响:共培养实验中,28个菌接种后形成杜鹃类菌根。与无菌苗相比,菌根苗植株较高,叶片多,根系长,分支多。无菌苗根系为白色细胞内无菌丝圈;菌根苗根系则呈现或深或浅的褐色,在表面会有菌丝缠绕并侵入表皮细胞中形成菌丝圈。
资助项目Northwestern Yunnan is one of the differentiation center of modern Rhododendron L.. Rhododendron species are the major composition of alpine and sub-alpine vegetation and the play vital roles in ecosystem in this region. Ericoid Mycorrhizas (ERM) is a specific mycorrhizal type between fungi and plants of three families in the Ericales: Ericaceae, Empetraceae and Epacridaceae. ERM play important roles in mediating stress and enhancing endurance of plants to survive in harsh wild condition. In order to find out the species diversity and function of ERM fungi in Rhododendron species in Yunnan, China, the multidisciplinary preliminary studies were performed: 1) The living environment of natural populations was investigated, and then roots of Rhododendron in natural populations were observed. 2) Three species of R. decorum, R. pachypodum and R. phaeochrysum were chosen to isolate and culture fungi from their toots. 3) Among them, species diversity and distribution of ERM fungi in R. decorum from three populations were identified and compared by morphological characteristics, molecular method and Simpson index. 4) The preliminary effect of ERM fungi on sterile seedlings of R. decorum was evaluated. The main results are summarized as follows.1. Living environment of Rhododendron,The result of field investigation showed that elevation altitude of Rhododendron distribution ranges from 2500m to 4650m. Some species such as R. telmateium and R. phaeochrysum grow in limestone and mine tailing areas with the pH of soil 7.0-7.1. Most plants grow in alpine coniferous, evergreen and deciduous broad-leaved mixed-wide forest, and the pH of soil is 5.4-6.9.2. Roots section observation, Roots section observation showed that ERM hyphal coils were present in epidermal cells of all hair roots of 17 Rhododendron species. In addition, we found clamp connections in the roots of 8 species in 19 populations. Dark septate endophytes were recognized in the hair roots under light microscope, too. It showed that ascomycetes and basidiomycetes might coexist in the roots. 3. Morphological characteristics of colonies,Nearly 400 slow-growing colonies were isolated and cultured in PDA medium from 500 roots of R. decorum, R. pachypodum and R. phaeochrysum. Their morphological characteristics were various. For example, the texture included fluffy, felty, floccose, and so on. The ridge shape is radialized, round or irregular. Some culture exudated white, brown or dark liquids during growth period. The shape of their conidiospore is round, spindly, bacilliform, and so on. Their growth rate ranges from 0.2-4mm/d (the growth of diameter of culture every day), while some are determinate growth. There were some isolations occurred many times while others occurred only one time in the culture. There were many different colonies among different Rhododendron and different populations especcially R. phaeochrysum. 4. Species diversity of ERM fungi in R. decorum,Twenty hundred and eighteen slow-growing colonies were isolated from R. decorum and 125 of them were ericoid mycorrhizal fungi. By observing morphological characteristics and using sequences of the nuclear ribosomal DNA ITS region, we identified them as 12 species. Except for 3 unidentified isolates, the other 9 belonged to 9 genera, 4 orders of Pezizomycotina. Four isolate morphotypes belong to Helotiales, so they are the dominant ERM species. Oidodendron maius (FJ999645) holds 18.4% of the whole cultured ERM fungi of R. decorum. However, its distribution was different among three populations. The ERM fungi isolated from R. decorum are rich and they are different from other reports in other regions. Some species were not reported as ERM fungi in other reportes such as Neonectria radicicola, Bionectria ochroleuca, and so on. There were 11,8 and 8 ERM fungi respectively in three populations with 7 occurred in three populations. It shows that total species diversity of mycorrhizal fungi isolated from R. decorm was high, with Simpson index 0.86 and Shannon-Weiner index 3.02. The species diversity of wild populations was higher than cultivated one. 5. Preliminary effect of ERM fungi on sterile seedlings of R. decorum,Thirty-eight representative isolates were chosen to test their ability of forming ERM with sterile seedlings of R. decorum and 28 were successful. The mycorrhizal seedlings are much higher and stronger than ordinary sterile seedlings. Their roots are much longer and intensive, too. The root tips and other region of mycorrhizal seedlings are brown with many hyphae around the root surface or penetrate the epidermal cells to form hyphal coils. But the sterile roots are white without any hyphae or hyphal coils in the cells.
语种中文
文献类型学位论文
条目标识符http://ir.kib.ac.cn/handle/151853/16058
专题昆明植物所硕博研究生毕业学位论文
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田伟. 中国云南西北地区杜鹃花菌根的多样性研究[D]. 中国科学院研究生院,2010.
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