【作者】 赵志慧；

【导师】 吕国忠；

【作者基本信息】 沈阳农业大学 ， 植物病理学， 2008， 博士

【摘要】 镰孢菌属(Fusarium)真菌是禾本科作物上最重要的病原真菌类群之一,也是重要的产毒真菌。因此,无论从植物病理学,还是从食品安全的角度来讲,对禾本科作物上的镰孢菌进行分类鉴定都具有非常重要的理论研究和实际应用意义。世界上的真菌分类学家多年来一直致力于不断提高镰孢菌分类水平,目前已经完成了镰孢菌中两个种的基因组序列测定,从分子水平上证明镰孢菌在寄主、地理分布上的多样性,发现了大量的新种和遗传上的多样性类群。这些被重新认识的镰孢菌在致病性、毒素等方面存在一定差异,在植物病理学、食品安全等方面具有重要意义。这些研究成果使人们对镰孢菌的研究进入了一个崭新的阶段。而我国近二十年来对镰孢菌的研究几乎处于停滞状态,这大大地阻碍了我国对镰孢菌病害的研究、以及出入境对镰孢菌病原的检测能力。为此,本论文采用与世界同一水平的形态学和分子生物学研究方法对重要的植物病原真菌—镰孢菌属真菌进行了分类研究,旨在明确我国禾本科作物上镰孢菌属真菌的种的多样性和遗传多样性,以及分布特点等,为镰孢菌引起的作物病害的病理学、流行学、病害防治等诸多方面的研究奠定基础,并为食品安全及出入境动植物产品中镰孢菌的快速和准确鉴定提供有益指导。本文对采自我国25个省、市、自治区的359份禾本科作物样品进行了镰孢菌的分离与培养,共获得了2100株的镰孢菌。采用传统的形态学分类和现代分子分类学方法,对我国禾本科作物上的镰孢菌进行分类和鉴定。共分离和鉴定出24个种的镰孢菌:F.verticillioides、F.fujikuroi、F.proliferatum、F.subglutinans、F.thapsinum、F.nygamai、F.oxysporum、F.solani、F.avenaceum、F.acuminatum、F.sinensis、F.poae、F.sporotrichioides、F.kyushuense、F.semitectum、F.bullatum、F.tangshanensis、F.pulveratum、F.equiseti、F.scirpi、F.reticulatum、F.graminearum、F.crookwellense、F.flocciferum。其中3个新种(F.sinensis,F.tangshanensis和F.pulveratum)、1个新组合(F.bullatum)和1个中国新记录种(F.kyushuense)。F.sinensis分离自山东省小麦,PDA上菌落酒红色,在单瓶梗上产生纺锤形、芜菁形两种小孢子及串生、聚生的厚垣孢子,与现存所有的镰孢菌相区别。同时,对F.sinensis及其近缘种F.avenaceum species complex的EF-1α序列片段进行了分析,从分子水平证明F.sinensis是一个与F.avenaceum近缘的单元进化群。中国新记录种F.kyushuense的特点是在多芽产孢细胞上产生大量拟纺锤形中孢子,PDA上菌落背面血红色,且不产生厚垣孢子,该种在世界上还未被普遍报道。直孢组作为禾本科作物上常见类群,在本试验中进行了较深入的研究。在研究中发现,F.pulveratum、F.tangshanensis和F.bullatum是符合直孢组形态特征的类群。本文从形态学上和分子水平证明它们是三个独立的种,分析了我国禾本科作物直孢组镰孢菌的遗传多样性。F.pulveratum从形态和EF-1α序列上与其它Fusarium种类明显不同,是一个显著的独立类群,这一类群以形成肉桂色粉末状菌落为最显著特征;F.tangshanensis和F.bullatum在形态和EF-1α序列分析上都是相近的类群,但F.tangshanensis大孢子从中部向两端逐渐弯曲变细,而F.bullatum较显著地在孢子上部突然弯曲,顶端收缩,两者形态上的差异与EF-1α序列分析结果一致,因此作为两个独立的种。本文研究从形态学和系统发育学水平上证明了F.bullatum既不应是自Gordon(1952)以来认为其是F.equiseti的异名,也不应是Burgess(1985)提出的F.scirpi的异名,而应为Sherbakoff(1915)提出的F.bullatum Sherb.。由于禾谷镰孢菌(F.graminearum)是我国小麦赤霉病的重要病原菌,本文筛选出19株F.graminearum进行EF-1α序列分析。结果表明,在我国禾本科作物上至少存在4个禾谷镰孢菌的谱系,其中谱系3为我国玉米上所特有,存在于玉米穗部和种子上。谱系2是我国首次报道的进化群,这一发现完成了谱系2在世界上从南美经尼泊尔向我国传播,进而进入韩国的这样一条传播路径。同时我国禾本科作物上的F.graminearum还有可能存在着更多的谱系。本文研究说明我国禾谷镰孢菌存在着丰富的遗传多样性,为今后我国禾谷镰孢菌的病害流行学和致病性等病理学方面的研究奠定了基础。更多还原

【Abstract】 The genus Fusarium Link is one of the most important pathogens on cereals,as well as one of the most important mycotoxin-producing fungi.It is necessary to keep continuous research on Fusarium taxonomy and identification in views of both phytopathology and food security.The fungal taxonomists all over the world have been making efforts to promote Fusarium taxonomy.Until now,the genome of two Fusarium species have been accomplished.As well as diversities of Fusarium species on hosts and geographic distribution based on molecular study have been explained,and large numbers of new species and their genetic diversities have been discovered.Unfortunately it has been short of taxonomic work on Fusarium in China especially in the past two decades,which,however,retarded Fusarium diseases and plant quarantine.This thesis was designed to focus on the modern morphological taxonomy and molecular systematics of Fusarium species isolated from cereals in China,in order to clear Fusarium diversity on geographic distribution and hosts in China.The correct identification of Fusarium species from gramineous crops would contribute to the study of Fusarium diseases.The thesis will contribute to the management of Fusarium diseases and food security.It is also helpful to plant quarantine in China.The Fusarium cultures were isolated from 359 cereal samples collected in 25 provinces and cities in China.The combination of traditional morphological classification and DNA sequence analysis were employed in the current study and more monographs on Fusarium classification were referenced.24 Fusarium species were identified and described:F. verticillioides,F.fujikuroi,F.proliferatum,F.subglutinans,F.thapsinum,F nygamai,F. oxysporum,F solani,F.avenaceum,F.acuminatum,F.sinensis,F.poae,F.sporotrichioides,F. kyushuense,F.semitectum,F bullatum,F.tangshanensis,F.pulveratum,F.equiseti,F scirpi, F.reticulatum,F.graminearum,F crookwellense,F.flocciferum,including three new species, F.sinensis Zhi-hui Zhao & Guo-zhong Lu,F.tangshanensis Zhi-hui Zhao & Guo-zhong Lu, and F.pulveratum Zhi-hui Zhao & Guo-zhong Lu,one new recombined species,F.bullatum, and a new record species for China,F.kyushuense.F.sinensis was characterized by carmine colony on PDA,fusiform and napiform microconidia on monophialides,chlamydospores in chains or clumps.The phylogenetic analysis of partial EF-lαsequence further confirmed the monophyletic F.sinensis clade.As a common group of Fusairum on cereals,species in section Arthrosporiella were studied morphologically and phylogenetically.Two new species F.pulveratum,F. tangshanensis and a new recombined species,F.bullatum,were discovered.F.pulveratum, which was characterized by a cinnamon and powdery conlony,is clearly different from the other groups morphologically and phylogenetically.F.tangshanensis and F.bullatum are similar to each other.The macroconidia of F.tangshanensis are curved and their widest position are located at the upper-middle region,and taper to each end,while the most curved and widest position of F.bullatum located at the terminal 1-2-cell.The morphological differences are coincident with EF-lαsequence phylogenic tree.It is indicated that F. bullatum as an independent species described by Sherbakoff(1915)should be conserved,it should not be treated as a synonym of F.equiseti(Gordon,1952)or F.scirpi(Burgess,1985).As F.graminearum is one of the most important pathogens of wheat head blight in China, 19 strains from cereals were selected for phylogenetic study.The phylogenetic tree based on 610bp EF-1αsequence reveals that at least four lineages of F.graminearum existed on gramineous crops in China.Among the four lineages lineage 3 was only isolated from maize, and lineage 2 was firstly reported in China.The discovery of lineage 2 confirmed the hypothesis that the immigration of lineage 2 from South America to Korea via China.更多还原