丛枝菌根真菌丛枝结构介导黄顶菊建群的营养机制

Flaveria bidentis is a noxious invasive weed, which can form arbuscular mycorrhiza with the indigenous arbuscular mycorrhizal fungi(AMF) in the invasive land. Arbuscule structure of arbuscular mycorrhiza is the place of nutrient exchange between AMF and host plants. Arbuscule structure changes during the succession of plants, and the nutrition metabolism in F. bidentis population formation may be influenced by this change. As to the nutrition mechanisms of F. bidentis invasion population formation mediated by arbuscule structure, traditional AMF study methods with molecular biological techniques will be used in the present study to investigate species composition, arbuscule structure features formed in roots of F.bidentis,as well as their relationship to the invasion.The dominant AMF species and arbuscule structure features in F.bidentis roots which are related to F.bidentis invasion will be examined.Through inoculation treatments, roles of different dominant AMF species in population formation of F.bidentis will be compared. On the basis of definition of dominant AMF species which is the best in increasing population formation of F.bidentis, the research on arbuscule structure features and their nutrient absorption, transportation and utilization characters, and their effects on growth of F.bidentis and its associated plants will be investigated to elucidate the nutrition mechanisms of F.bidentis invasive population formation mediated by arbuscule structure. The finding of this study is expected to provide a guidance controlling F.bidentis, and help illustrate the position of AMF in exotic plant invasion. It will also provide the theoritical foundation and technical support for carrying out the relative researches and the weed-control practice.

恶性入侵杂草黄顶菊在入侵地可与土著丛枝菌根真菌建立互惠共生关系，形成丛枝菌根。该菌根的丛枝结构是真菌与寄主植物进行养分交换的场所。植物演替过程中，丛枝结构特征发生变化。这一变化很可能影响黄顶菊建群的营养代谢过程。本项目紧密围绕丛枝结构介导黄顶菊入侵建群的营养机制，采用丛枝菌根真菌传统研究方法结合分子生物学技术，重点研究：黄顶菊根内丛枝菌根真菌种类、丛枝结构特征及其与黄顶菊入侵的关系，确定与黄顶菊入侵相关的优势丛枝菌根真菌及其丛枝结构特征；通过接种处理，比较优势丛枝菌根真菌对黄顶菊建群的作用；在确定对黄顶菊建群作用最大的优势丛枝菌根真菌种类的基础上，通过对丛枝结构特征及其养分吸收、运转与利用特点、黄顶菊及伴生植物生长的效应研究，明确丛枝结构介导黄顶菊入侵建群的营养机制。该研究结果可望为控制黄顶菊提供参考，有助于阐明丛枝菌根真菌在外来植物入侵中的地位，以期为开展相关研究和防控实践提供依据。

采用丛枝菌根真菌(AM)传统研究方法结合分子生物学技术，研究黄顶菊根内丛枝菌根真菌种类、丛枝结构特征及其与黄顶菊入侵的关系，确定与黄顶菊入侵相关的优势丛枝菌根真菌及其丛枝结构特征。在黄顶菊入侵严重的河北省衡水地区选择采样地点，分别从滨湖新区小北田村、顺民庄村、刘家台村、冀州市漳下村、枣强县北王庄村、桃城区八里庄村6个地点按黄顶菊重、中、轻3种盖度和不同生育期（苗期、花期和结籽期）采集根系和根区土样。分离根区土壤中AM真菌孢子，观察AM发育特征、测定孢子密度和菌丝侵染率等。在各采样地点均观察到AM典型结构，菌丝侵染率、I型丛枝密度以及孢子密度的最大值均出现在八里庄村，泡囊密度和A型丛枝密度的最大值分别出现在小北田村和刘家台村；不同盖度下AM真菌侵染率最高值均出现在重度侵染区；不同生长时期黄顶菊的AM也有差异，除了丛枝密度最高值出现在花期和菌丝侵染率差异不显著外，菌丝侵染率、泡囊密度和孢子密度均在结籽期出现最大值。菌丝侵染率与土壤有机质呈显著正相关，与pH值呈显著负相关，与速效P含量呈极显著负相关；A型丛枝密度与pH含量呈显著负相关；I型丛枝密度与土壤全N含量呈极显著正相关；孢子密度与有机质含量和全N含量均呈显著正相关。共分离鉴定黄顶菊根围AM真菌孢子2属26种，其中球囊霉属(Glomus)占69%，无梗囊霉属（Acaulospora）占31%。出现频度较高为摩西球囊霉（G. mosseae）、光壁无梗囊霉（A. laevis）、地表球囊霉(G. versiforme)和根内球囊霉(G. intraradices)。经进一步根段扩繁鉴定优势种为摩西球囊霉和根内球囊霉。不同优势种组合接种对黄顶菊的生长发育产生差异性影响，AM真菌复合接种明显比单接的促进作用强。因此，AM真菌侵染可能会促进黄顶菊的入侵。这将为进一步开展丛枝结构发育特点及其介导黄顶菊入侵建群的营养机制研究奠定基础。. .