Physiology and genetics of nitrogen uptake and metabolism in trees

植物面临着扎根的独特挑战。它们必须在一生中从有限的土壤中获得养分--就树木而言，需要几个世纪的时间。在加拿大，森林土壤通常是寒冷、酸性的，有效养分含量很低，特别是氮。了解树木对这些土壤的适应，以及这些适应如何影响树木对气候变化的反应，是一个重要的实用和科学目标。在自然系统中，树根与真菌伙伴菌根共生，菌根对养分的矿化、吸收和向宿主的转移至关重要。菌根物种在分解有机物和吸收养分的能力以及对非生物因素的反应方面有所不同。这对气候变化中的树木营养具有重要意义。我们对菌根之间的变化以及温度或二氧化碳对这些共生生物的影响知之甚少。这项建议描述了一个关于树根及其相关菌根真菌的研究计划，以及在不同的温度、氮素有效性和二氧化碳条件下，这些共生体对氮素吸收和氮素形态偏好的影响。

Plants face the unique challenge of being rooted in place. They must acquire nutrients from a limited volume of soil over an entire lifetime - in the case of trees, over centuries. In Canada, forest soils are typically cold, acidic and low in available nutrients, particularly nitrogen (N). Understanding the adaptations of trees to these soils, and how these may shape tree response to changing climates is an important practical and scientific goal. In natural systems, tree roots associate with fungal partners, mycorrhizae, that are vital to nutrient mineralization, uptake and transfer to the host. Mycorrhizal species differ in their ability to break down organic matter and take up nutrients, and in their response to abiotic factors. This has important implications for tree nutrition in changing climates. We know little about variation among mycorrhizae or about the effects of temperature or CO2 on these symbioses. This proposal describes a program of research on tree roots and their associated mycorrhizal fungi, and the effects of these symbioses on N uptake and N-form preference under contrasting temperatures, N availability and CO2.