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: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=589729
• 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.

树木将其大部分生产力分配给其细小的饲养根。在北部森林中，大多数根部都被外生菌根真菌定殖，这种真菌共生体有助于吸收养分和水分，以换取植物糖分。尽管外生菌根细根的周转代表了土壤生态系统中碳和氮的大量输入，但我们对所涉及的分解者以及所释放的资源的命运知之甚少。外生菌根细根大约有 40% 是真菌组织，其中含有几丁质，因此比植物组织显着更多的氮。然而，尚不清楚哪些生物体主导了森林土壤中真菌的分解。细菌与真菌的分解会影响土壤养分的可用性和碳封存，因为资源通过细菌群落的移动速度比通过真菌群落的速度更快。细菌被认为是碱性土壤中甲壳质的主要分解者，而土壤真菌被认为在酸性条件下更为重要。然而，真菌的细菌分解可能会随着温度的升高而增加，因此在温暖的气候下，更大比例的真菌碳和氮可能会穿过更不稳定的细菌群落。细根内部也有内生真菌定殖。尽管人们对这些真菌的生态作用知之甚少，但它们可能参与外生菌根植物成分的分解，并且很好地定位在根组织内。形成特定外生菌根的共生真菌也可能影响其分解速度，因为某些物种会产生抗菌化合物。