Decomposition of ectomycorrhizal fine roots

外生菌根细根的分解

• 批准号: RGPIN-2015-04323
• 负责人: Kernaghan, Gavin
• 金额: $ 1.75万
• 依托单位: Mount Saint Vincent University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=655348
• 关键词: Decomposition; ectomycorrhizal; fine; roots

Trees allocate a large portion of their productivity to their fine feeder roots. In northern forests, the majority of these roots are colonized by ectomycorrhizal fungi - fungal symbionts that aid in nutrient and water uptake in exchange for plant sugars. Although the turnover of ectomycorrhizal fine roots represents an enormous input of carbon and nitrogen into the soil ecosystem, we have very little information regarding the decomposers involved, and therefore the fate of the resources liberated. Ectomycorrhizal fine roots are approximately 40% fungal tissue, which contains chitin and therefore significantly more nitrogen than plant tissue. However, it is not clear which organisms dominate the breakdown of fungi in forest soils. Bacterial vs fungal decomposition impacts both soil nutrient availability and carbon sequestration, as resources move more quickly through bacterial communities than through fungal communities. Bacteria are thought to be the dominant decomposers of chitin in alkaline soils, and soil fungi are considered to be more important under acidic conditions. However, bacterial decomposition of fungi may increase with higher temperatures, such that a larger proportion of fungal carbon and nitrogen may move through the more labile bacterial community in a warmer climate. Fine roots are also colonized internally by fungal endophytes. Although the ecological roles of these fungi are poorly understood, they may be involved in the decomposition of the plant component of ectomycorrhizae, and are well positioned within the root tissue. The symbiotic fungus forming a given ectomycorrhiza may also influence its decomposition rate, as some species produce antimicrobial compounds. ***The objectives of the proposed research are to: 1) determine which decomposers utilize the fungal component of ectomycorrhizae under different environmental conditions using DNA based techniques, 2) track microbial activity during the decomposition of whole ectomycorrhizae using RNA techniques (gene expression) and 3) determine the decomposition rates of ectomycorrhizae formed by different fungal species, characterizing the antimicrobial compounds produced by recalcitrant species. ***A prominent feature of the Canadian landscape is the boreal forest, an ecosystem in which all dominant tree species form ectomycorrhizae. Knowing the relative importance of bacteria, soil fungi, root endophytes and ectomycorrhizal fungi in the process of fine root decomposition is key to resolving the pathways though which the resulting fluxes of resources move through our northern forests. Information on the dynamic roles of soil microbes under varying environmental conditions, including those expected under climate change, is also critical to understanding present and future boreal forest ecosystem function. ********

树木将其生产力的很大一部分分配给了优质的喂食器根。在北部森林中，大多数根源是由外生菌触真菌 - 真菌共生体殖民的，这些真菌共生体有助于营养和摄入水，以换取植物糖。尽管外生菌血细胞的流失量代表了碳和氮对土壤生态系统的巨大输入，但我们对所涉及的分解器的信息很少，因此资源的命运被解放了。外生肌肉细根大约是40％的真菌组织，其含有几丁质，因此比植物组织明显更多。但是，目前尚不清楚哪种生物在森林土壤中占主导地位。细菌与真菌分解会影响土壤养分的可利用性和碳固相，因为资源与细菌群落相比，与通过真菌群落相比，资源更快。细菌被认为是碱性土壤中几丁质的主要分解剂，在酸性条件下，土壤真菌被认为更为重要。但是，真菌的细菌分解可能会随着较高的温度而增加，因此，在温暖的气候下，更大比例的真菌碳和氮可能会在更不稳定的细菌群落中移动。精美的根部也被真菌内生植物内部殖民。尽管这些真菌的生态作用知之甚少，但它们可能参与了外生霉菌的植物成分的分解，并且位于根组织中。形成给定外生菌的共生真菌也可能影响其分解速率，因为某些物种产生了抗菌化合物。 ***拟议的研究的目标是：1）确定使用基于DNA的技术在不同的环境条件下使用外生菌骨的真菌成分，2）在整个骨膜分解过程中，使用RNA技术（Gene Expression）和3）在整个骨膜内的分解过程中跟踪微生物的活性（3）。顽固物种产生的抗菌化合物。 ***加拿大景观的一个突出特征是北方森林，这是一个生态系统，在该生态系统中，所有主要的树种形成了外生菌。了解细菌，土壤真菌，根部内生菌和外生菌的真菌在细根分解过程中的相对重要性是解决途径的关键，尽管所产生的资源通量通过北部森林而移动。有关土壤微生物在不同环境条件下的动态作用的信息，包括在气候变化下的预期，对于理解当前和未来的北方森林生态系统功能也至关重要。 ********