干热河谷不同树龄攀枝花苏铁丛枝菌根真菌多样性研究

攀枝花苏铁是我国特有的古老残遗树种，为适应干热河谷气候，攀枝花苏铁与丛枝菌根真菌（arbuscular mycorrhizal fungi，AMF）建立特殊的共生体系。选用不同树龄的攀枝花苏铁为研究对象，采集攀枝花苏铁根系及根际土壤样品，采用醋酸墨水染色法观察根系的AMF定殖情况并计算定殖率；同时采用湿筛沉淀法对AMF孢子进行分离，通过形态学特征及分子生物学鉴定相结合的方法研究攀枝花苏铁AMF的种类、多样性及与树龄的关系。结果表明，14年生、8年生和3年生攀枝花苏铁根系AMF定殖率分别为36.13%、28.54%、21.10%；根际土壤AMF孢子密度分别为16.02、14.13、13.3个·g^-1，形态学鉴定到6属22种，分别为球囊霉属（Glomus）、无梗囊霉属（Acaulospora）、近明球囊霉属（Claroideoglomus）、斗管囊霉属（Funneliforms）、盾巨孢囊霉属（Scutellospora）和硬囊霉属（Sclerocystis），球囊霉属和无梗囊霉属为优势属，相对多度分别为56.91%和28.23%。分子生物学鉴定到3属6种，分别为近明球囊霉（C.claroideum）、明球囊霉（G.clarum）、缩球囊霉（G.constrictum）、无梗囊霉属（A.srobiculata）、黑球囊霉（G.melanosporum）和地表球囊霉（G.versiforme）。统计分析表明，AMF定殖率与AMF孢子密度之间的相关性是0.873 9，呈显著的正相关关系。该研究为攀枝花苏铁的保育提供了理论依据。

Diversity of Arbuscular Mycorrhizal Fungi in Cycas panzhihuaensis at Different Tree Ages in Dry Hot Valley

Cycas panzhihuaensis,a unique species in China,can grow the dry and hot valley climate,because it can form a symbiotic system with arbuscular mycorrhizal fungi (AMF).In this study,C.panzhihuaensis trees with different ages were taken as the study objects,and the root system and rhizosphere soil samples were collected to examine the AMF community composition and colonization rate by using ink-vinigar staining method.The spores of AMF were separated by wet sieve precipitation,and the relationship between AMF diversity and tree age were studied by morphological and molecular biological identification method.It was found that the colonization rates of 14-,8-,and 3-year-old trees were 36.13%,28.54% and 21.10% respectively,and the AMF spore densities were 16.02,14.13,and 13.3 spores per gram of soil,respectively.Twenty two AM fungi belonging to 6 genera were morphological identified,including Glomus,Acaulospora,Claroideoglomus,Funneliform,Scutellospora,and Sclerocystis.Glomus and Acaulospora were the most dominant genera with the relative abundances of 56.91% and 28.23%,respectively.Six AM fungi belonging to 3 genera were molecular identified,including Claroideoglomus claroideum,Glomus clarum,G.constrictum,Acaulospora srobiculata,G.melanosporum and G.versiforme,respectively.The correlation coefficient between arbuscular mycorrhizal colonization rate and AMF spore density was 0.873 9,showing a significant positive correlation.The result provides a theoretical basis for the conservation of C.panzhihuaensis.