内蒙古中东部草原羽茅Epichloё属内生真菌的分布及rDNA-ITS序列系统发育  

Distribution and rDNA-ITS sequence analysis of Epichloё endophyte symbiosis with Achnatherum sibiricum in mid-and eastern Inner Mongolia Steppe

作　　者：张欣[1] 李熠[1] 魏宇昆[1] 王银华[1] 林枫[1] 任安芝[1] 高玉葆[1] 

机构地区：[1]南开大学生命科学学院,天津300071

出　　处：《生态学报》2007年第7期2904-2910,共7页Acta Ecologica Sinica

基　　金：国家重点基础研究发展计划资助项目(2007CB106802);国家自然科学基金资助项目(30370239)~~

摘　　要：对内蒙古中东部地区分布的羽茅6个地理种群的染菌率进行了调查,采集种子并从中分离得到不同形态型的内生真菌,选取其中的19株进行rDNA-ITS片段的扩增、克隆、测序和系统发育分析。结果表明:(1)6个样地羽茅种群内生真菌感染率除西乌旗为96.7%外,其他5个样地均为100%,表明内生真菌侵染羽茅并非偶然现象,二者之间存在一种稳定的共生关系。(2)ITS和5.8S序列得到的N-J树显示,相对于Epichloё属的其他参考菌株,不同地理种群羽茅中的内生真菌聚为一类,形成一个具有97%支持强度的分支。由此推测,不同地理种群羽茅中的内生真菌具有相同的起源点。(3)结合形态观察结果和rDNA-ITS序列分析结果可以看出,羽茅内生真菌种群的优势种亲缘关系较近,可能起源于同一种内生真菌;但由于其地理分布广、气候差异大、群落类型差别也较大,从而造成不同地理种群内生真菌形态上的分化以及种群间明显的遗传分化和较高的遗传多样性。The complex functions of fungal endophytes have received intensive study during the past three decades because of their roles in production loss of livestock and enhancement of biotic and abiotic stress resistances in hosts. Most of these studies focused on cultivated grasses, but little is known about the distribution and mechanisms of endophytes in native grass populations. Surveys of grass species associated with Neotyphodium and Epichloё fungal endophytes made in native grasslands of northern China suggested that endophytes are widely distributed in natural grass populations. Among them, Achnatherum sibiricum was found to associate with fungal endophytes in all sites investigated. Ach. sibiricum is a perennial, grass that inhabits temperate steppe in China. This grass can be found in different habitats such as meadows, typical steppes and forests. Its distribution may be largely determined by precipitation, while it is usually a companion species incommunities and it sometimes can become the dominant species. Untill now, no toxicosis problems in grazing animals have been reported in pastures containing Ach. sibiricum. Six natural populations （ IMGERS-CAS, Leymus chinensis Arshan, Hailar） of Ach. sibiricum in mid- and eastern Inner M plot of the IMGERS-CAS, Xi Ujimqin Qi, H ongolia Steppe of varying distances from each other were chosen. Locations and descriptions of sampling sites were recorded. Infection frequency of fungal endophytes was detected and seeds from 30 Ach. sibiricum individuals were collected. Fungal endophytes of different morphologies were isolated from seeds and at each site, strains of different morphologies were used as internal transcribed spacers of the nuclear ribosomal DNA （rDNA-ITS） sequence analysis. Regions of rDNA-ITS were amplified, cloned, sequenced and submitted to GenBank. Furthermore, phylogenetic analysis was conducted with additional sequences conserved in GenBank. Fungal endophytes were found at high frequencies in all investigated local populations regardles

关 键 词：羽茅 内生真菌 系统发育 RDNA-ITS 

分 类 号：S182[农业科学—农业基础科学]