DISSERTATION RESEARCH: Plant interactions across common mycorrhizal networks

本研究关注共同菌根网络（CMNs）在植物地下竞争中的作用，“植物根系间的真菌相互联系”。CMNs通常是由有益的、居住在根上的真菌形成的，这些真菌被称为“丛枝菌根真菌”。植物通过光合作用为这些真菌提供一些糖，作为回报，真菌吸收并为植物提供关键的矿物质营养物质，如磷和氮。一旦连接到寄主植物的根部，真菌就会在整个土壤中觅食，并可能遇到其他植物物种的根系，它们也会不加偏好地与之联系，从而形成一个网络。这引发的主要问题是，是否所有连接到这个网络的植物都公平地分享矿物质营养，或者菌根真菌是否不成比例地向宿主植物捐赠矿物质营养，而宿主植物为它们提供最多的糖。研究人员利用高草草原物种进行研究，大蓝茎和加拿大野黑麦。高草草原是北美濒临灭绝的生态系统，草原恢复通常涉及将研究物种一起播种。了解CMNs如何影响这些植物物种之间的相互作用可能会为恢复管理实践提供信息，例如耕作，这可能会破坏CMNs。除了与草原恢复相关外，本研究还将吸引来自代表性不足群体的迈阿密市中心中学生和大学本科生。研究人员将研究CMNs在高草草原优势草大蓝茎（Andropogon gerardii）和不太常见的物种加拿大野黑麦（Elymus canadensis）之间介导的竞争。如果大蓝茎能够不成比例地获得矿质养分，从而抑制加拿大野黑麦的生长，那么CMNs可能有助于大蓝茎的优势地位，影响草原群落组成。研究人员将在温室中使用旋转容器方法，通过切断cmnss来隔离和揭示其影响。拟议的工作将确定CMNs对种内和种间竞争的相对强度以及随之而来的规模等级发展的影响。该学生将通过碳稳定同位素比率来比较ec4和C3草在单一栽培和混合栽培下提供的碳与叶片矿质养分含量，研究向CMNs的大量碳捐赠是否会引起菌根真菌的高矿质养分转移。最后，如果切断CMNs会改变根系上的真菌群落，这将通过DNA条形码进行研究。

This investigation concerns the role of common mycorrhizal networks (CMNs) "fungus interconnections among plant root systems" in plant competition belowground. CMNs are formed by generally beneficial, root-inhabiting fungi called "arbuscular mycorrhizal fungi". Plants feed these fungi some of the sugar they produce by photosynthesis, and in return, the fungi take up and provide the plants with key mineral nutrients such as phosphorus and nitrogen. Once connected to a host plant's roots, the fungi forage throughout the soil and may encounter root systems of other plant species with which they additionally associate without preference, creating a network. The major question this raises is whether all plants connected to the network share mineral nutrients equitably or if mycorrhizal fungi disproportionately donate mineral nutrients to host plant species that provide them the most sugar. The researchers utilize tallgrass prairie species for their research, Big Bluestem and Canada Wild Rye. Tallgrass prairie is an endangered ecosystem in North America and prairie restorations often involve sowing the study species together. Understanding how CMNs affect interactions between these plant species might inform restoration management practices such as tillage, which can disrupt CMNs. Besides its relevance to prairie restoration, this research will engage Miami inner-city middle school students and university undergraduates from underrepresented groups. The researchers will investigate competition as mediated by CMNs between a tallgrass prairie dominant grass, Big Bluestem (Andropogon gerardii) and a less common species, Canada Wild Rye (Elymus canadensis). If Big Bluestem is able to obtain mineral nutrients disproportionately and thereby suppress the growth of Canada Wild Rye, then CMNs may contribute to Big Bluestem's dominance, influencing prairie community composition. The researchers will utilize a rotated conetainer method in the greenhouse to isolate and reveal the effects of CMNsby severing them. The proposed work will determine the effects of CMNs on the relative strengthsof intra- and interspecific competition and consequent size hierarchy development. The studentwill investigate if large carbon donation to CMNs elicits high mineral nutrient transfer frommycorrhizal fungi by using carbon stable isotope ratios to compare carbon supplied by theseC4 and C3 grasses to their leaf mineral nutrient contents in monoculture and mixture. Finally,if severing CMNs alters the fungus community on root systems, this will be investigated through DNA barcoding.