【作者】 张琪；

【导师】 丁琼；

【作者基本信息】 海南大学 ， 观赏园艺， 2018， 硕士

【摘要】 植物的根部真菌(root-associated fungi,RAF)是生长在植物根系内部、表面的真菌总称。这类真菌具有多样性的营养型,如共生、腐生、致病型等,在生态系统中具不同的功能,对生态系统的养分循环和植物群落的组配有重要作用。樟科与无患子科植物是海南尖峰岭热带山地雨林的常见植物,研究樟科与无患子科植物RAF的多样性、生态功能、种间关系,以及探讨宿主植物和空间因子对植物RAF群落组配的影响,将有助于揭示热带雨林物种共存及多样性维持机制。本研究依托尖峰岭热带山地雨林大型固定样地,通过分子检测技术鉴定植物RAF种类,揭示尖峰岭樟科与无患子科植物的RAF物种多样性、群落结构、生态类型,以及RAF的种间关系;在此基础上,采用Mantel、邻体矩阵主坐标、冗余分析等方法,检验空间因子与宿主对RAF群落物种组成的影响。主要研究结果如下:本研究检测到的RAF物种多样性较高,真菌物种达393种。在门水平上,按物种数由高到低依次是子囊菌门、担子菌门、毛霉菌门以及壶菌门几个真菌类群,此外还有20种真菌无法鉴定到门。在纲水平上,物种数排前五的依次是伞菌纲、球囊霉纲、锤舌菌纲、粪壳菌纲和座囊菌纲。可鉴定到目水平的RAF有215种,排前五的依次是球囊霉目、伞菌目、柔膜菌目、红菇目和刺盾炱目。科水平上,物种丰富度排前三的依次是球囊霉科、红菇科和晶杯菌科。本研究仅有58种RAF能鉴定到属的水平,分属于33个属,其中物种数最丰富的是毛霉菌门的Rhizophagus,其次是球囊霉属、被孢霉属,以及担子菌门的红菇属。本研究中RAF的生态类型也较为丰富,有122种真菌可划分到各营养型和功能群,按营养型可分为共生型、腐生型、病原型、病原-腐生兼性营养型、病原-腐生-共生兼性营养型5个类型,其中共生型真菌丰富度最高。按照功能群划分,物种丰富度最高的为共生型的丛枝菌根真菌,达68种。樟科植物与无患子科植物的RAF群落物种组成存在显著差异(P<0.01),AMF偏好樟科植物,而子囊菌门真菌和担子菌门真菌则更偏好无患子科植物,但在群落水平上,宿主植物这一影响因子对RAF群落物种组成变异的解释量非常有限。空间自相关性分析结果表明:小尺度的采样距离上(6-14m),真菌物种组成与空间距离存在显著正相关(物种组成相似性随距离减少而增加);而当距离超过一定数值时(29 m左右),真菌组成即出现显著的差异性。RAF群落物种组成的空间自相关性在空间尺度上存在不确定性,本研究的5个样方中,只有60%的样方中的RAF和AMF群落组成在6.6 m、13.8 m、28.6 m距离等级上的表现出显著的空间自相关性,而其它的几个样方并没有明显的空间自相关性。相比之下,在较大尺度(300 m × 500 m样方)范围内,邻体矩阵主坐标分析结果表明空间因子对RAF群落组成的影响极小。对RAF群落的种间关系分析表明,樟科与无患子科植物的RAF,无论是分析所有的393种真菌,还是仅分析62种常见真菌,RAF群落的C-score均显著高于零模型预测值,即RAF的种间呈竞争关系。除了病原真菌,其它生态类型的RAF,如AMF、外生菌根真菌和腐生真菌群落在空间上的种间关系整体均表现为竞争。这一结果说明真菌种间竞争是热带山地雨林的RAF群落在小尺度上的一个重要的组配机制。更多还原

【Abstract】 Root-associated fungi(RAF)are termed for soil fungi that grow in,on and out of the plants root system.RAF can be categorized into several functional groups according to their trophic modes,such as symbiotic,saprophytic,and pathogenic types.These functional groups are essential for nutrient cycling and community assembly.Lauraceae and Sapindaceae plants are dominant plant species in the tropical montane rainforest of Hainan Island.Studying the diversity,ecological functions,and interspecific relationships of RAF of Lauraceae and Sapindaceae,and exploring the effects of host plants and spatial factors in shaping the RAF community structuring,will help reveal the species diversity and coexistence mechanisms in tropical forests.In this study,RAF were identified from root tips of plant in family Lauraceae and Sapindaceae dominating the tropical montane rain forest of Jianfengling by molecular analysis of fungal ITS region.RAF diversity,community structure,ecological type,interspecific relationships were characterized.We also probed into questions,such as to what extend the RAF community can be structured by host plants and space.The main findings of this study are as follows:(1)The RAF community was characterized by high diversity that a total of 393 fungal species were detected in this study.At the phylum level,the number of species ranked from high to low were Ascomycota,Basidiomycota,Mucoromycota,and Chytridiomycota,while there are 20 species of RAF that cannot be assigned to a know phylum.At class level,the top five fungal groups with highest number of fungal species were Agaricomycetes,Glomeromycetes,Leotiomycetes,Sordariomycetes and Dothideomycetes.215 species can be assign to a known order,with Glomerales,Agaricales,Helotiales,Russulales and Chaetothyriales are the most species rich groups.RAF community are well represented by fungi from family Glomeraceae,Russulaceae and Hyaloscyphaceae.Only 58 RAF species could be assigned to fungal genera,with Rhizophagus was the most abundant species,followed by Glomus,Mortierella and Russula.(2)Trophic mode of the RAF was varied,with 122 out of the 393 RAF can be assign to a given functional group,eg.,symbiotroph,saprotroph,pathotroph,pathotroph-saprotroph,and pathotroph-saprotroph-symbiotroph.Symbiotic fungi,being represented by the AM fungi,have the highest number of species(68).(3)There were significant differences in the species composition of RAF community between Lauraceae and Sapindaceae plants.In general,the AMF prefers Lauraceae plants,while Ascomycota and Basidiomycota tend to associated with plants in Sapindaceae,but limited portions of variations in RAF community composition was explained by plant identity.(4)Spatial autocorrelation on RAF and AMF species composition were detected at the distance of 6-14 m,whereas no effect was found at larger distance scale,29 m.Plot based Mantel tests indicated that,spatial structure of RAF and AMF are not constant,that 3 out of 5 plots showed significant spatial autocorrelation at distances of 6.6 m,13.8 m,or 28.6 m,while the other two plots did not show distinct distance effects.PCNM analysis shows spatial factors only has little influence on RAF community composition at lager scale.(5)The RAF community of Lauraceae and Sapindaceae are featured by a competitive relationship that the observed C-scores were significantly higher than the value predicted by null model.Co-ocurrence analysis carried out for different fungal group,i.e.,AMF,ectomycorrhizal fungi,and saprophytic fungi communities are all showed competitive relationships,while interspecific relationship between pathogenic fungi were randomly arranged.These findings suggest that competition is an important mechanism for RAF community assemblage in tropical montane rain forest of Hainan Island.更多还原