Specificity of plant-microbe interactions in forest soils

森林土壤中植物-微生物相互作用的特异性

• 批准号: RGPIN-2014-04017
• 负责人: Grayston, Susan
• 金额: $ 1.97万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=632202
• 关键词: Specificity; plant; microbe; interactions; forest

Forestry is critical to Canada’s economic prosperity, nearly half Canada’s landmass is forested and Canada contains 10% of the world’s forests. In British Columbia forestry is the key industry, over half the province is forested. In addition, forests are vital for moderating climate and filtering air and water and as places of recreation. There is increasing emphasis on sustainable forest management, balancing resource extraction with retention of ecosystem services and biodiversity. In order to provide a basis for rational decisions forest managers must have sufficient knowledge about how forests function and how their management affects that functioning. Nutrient cycling and uptake have been shown to be critical processes for the health of forest ecosystems. The soil microbial community has a key role in nutrient cycling processes in soil through decomposition of soil organic matter and turnover of inorganic nutrients and minerals and, therefore, forest productivity. Soil microorganisms are also crucial to global climate, being responsible for the production and consumption of greenhouse gases (GHG). Although the importance of the soil microbial community is clearly recognized, we know very little about the diversity of microorganisms in soil, what their functional roles are and what factors influence the size, the structure and the activity of the microbial community. Mycorrhizal (fungus-root) associations are ubiquitous in forests though the reasons why certain tree species such as Douglas-fir can associate with up to 2,000 different fungal species and red alder only 50 remains an enigma. Equally, there is little comprehension of the specificity, seasonality and succession of these fungal associations with tree roots or how the growth pattern of different fungal species through the soil affects spatial variability in nutrient availability, through interactions with other soil microorganisms (e.g. bacteria and archaea). Developing management strategies for forest ecosystems requires an understanding of the processes regulating soil nutrient cycling and the impact of various management practices on these processes. A key to this understanding is an understanding of carbon flow and signals between trees, their mycorrhizal associates and their interactions with free-living microorganisms. Similarly, there is a paucity of information on GHG from natural ecosystems, particularly methane (CH4) and nitrous oxide (N2O), which have 30 and 300 times the global warming potential of CO2, respectively. Our knowledge of GHG fluxes from forest soils are complex, contradictory and essentially unknown because the microbes responsible for emission and consumption of these gases are uncultured and methods for studying these organisms did not exist until recently. This research program will use a variety of novel molecular and biochemical methods coupled with stable isotope labeling and probing approaches to identify the important micro-organisms, their specificity in plant interactions and elucidate their role in soil processes such as nutrient cycling, greenhouse gas fluxes and the storage or release of carbon, and clarify the manner in which they interact with plant roots. This will result in a better understanding of ecosystem functioning. This research will also provide new insight into the regulation of important non-CO2 greenhouse gases at both landscape and microbial levels in the soil. Gaining this new knowledge will provide the basis to make sound assessments of carbon sequestration under global change and develop forest management strategies that can meet future mitigation demands.

林业对加拿大的经济繁荣至关重要，加拿大近一半的陆地是森林，加拿大拥有世界森林的10%。在不列颠哥伦比亚省，林业是关键产业，全省一半以上的地区都是森林。此外，森林对于调节气候、过滤空气和水以及作为娱乐场所至关重要。人们越来越重视可持续森林管理，在资源开采与保持生态系统服务和生物多样性之间取得平衡。为了提供合理决策的基础，森林管理人员必须充分了解森林如何运作以及森林管理如何影响这种运作。养分循环和吸收已被证明是森林生态系统健康的关键过程。土壤微生物群落在土壤养分循环过程中发挥关键作用，通过分解土壤有机质和周转无机养分和矿物质，从而提高森林生产力。土壤微生物对全球气候也至关重要，负责产生和消耗温室气体（GHG）。尽管土壤微生物群落的重要性已被人们所认识，但我们对土壤中微生物的多样性、它们的功能作用以及影响微生物群落的大小、结构和活性的因素知之甚少。菌根（真菌根）协会是普遍存在于森林中，虽然为什么某些树种，如花旗松可以与多达2,000种不同的真菌物种和红桤木只有50个仍然是一个谜。同样，很少有人理解的特异性，季节性和继承这些真菌协会与树根或不同的真菌物种的生长模式如何通过土壤影响养分供应的空间变异性，通过与其他土壤微生物（如细菌和古细菌）的相互作用。制定森林生态系统管理策略需要了解调节土壤养分循环的过程以及各种管理实践对这些过程的影响。理解这一点的关键是理解树木之间的碳流和信号，它们的菌根关联及其与自由生活的微生物的相互作用。同样，关于自然生态系统产生的温室气体，特别是甲烷（CH 4）和一氧化二氮（N2 O）的资料也很少，这两种气体的全球升温潜能值分别是CO2的30倍和300倍。我们对森林土壤温室气体通量的了解是复杂的、矛盾的，而且基本上是未知的，因为负责排放和消耗这些气体的微生物是未培养的，研究这些生物的方法直到最近才存在。该研究计划将使用各种新的分子和生物化学方法，结合稳定同位素标记和探测方法，以确定重要的微生物，它们在植物相互作用中的特异性，并阐明它们在土壤过程中的作用，如养分循环，温室气体通量和碳的储存或释放，并阐明它们与植物根系相互作用的方式。这将有助于更好地了解生态系统的功能。这项研究还将为土壤中景观和微生物水平上重要的非CO2温室气体的调节提供新的见解。获得这一新知识将为合理评估全球变化下的碳固存和制定能够满足未来减缓需求的森林管理战略奠定基础。