Above/Belowground Linkages

GUIDING PRINCIPLES

Plant-soil biodiversity linkages such as mycorrhizal symbioses are recognized as key players in ecosystem function and resilience. Mechanisms include: the modulation of soil nutrient (N/P) bioavailability, the stabilization of soil matrix structure, and the enhancement of soil-microbial composition. Recently, Harris (2009) proposed that understanding these processes promises to enhance ecosystem recovery whereby tiny-scale organisms can have large-scale impacts even among the most degraded environments. This field/greenhouse module seeks to identify above/belowground linkages as underlying mechanisms for native plant revegetation among natural vs. rehabilitated ecosystems focusing on mycorrhizal symbiosis and their impact on the soil environment.

Dynamics of Arbuscular Mycorrhizal (AM) Symbiosis

Recent investigative interests focusing on plants and their allied soil-symbionts would suggest an important and multi-lateral impact of soil microbes in plant nutrient uptake and the regulation of soil nutrient availabilit. Focusing especially on the arbuscular mycorrhizal (AM) fungi − the most widely investigated form of mycorrhizal symbiosis within the context of both crop production and metal phytoremediation − this module examines the primary mechanisms by which plant-soil interactions shape plant stress tolerance in relation to metal stress, i.e., from deficiency to toxicity conditions, and further outlines how these properties could be applied toward the phytoremediation of metal polluted environments.

Thereafter, these multilateral effects are examined in a holistic depiction of the dynamics of AM-symbiosis as a function of plant metal stress tolerance along with some of the eco-physiological boundaries in up-scaling these processes (e.g., relating to the cost of maintaining the symbiotic infrastructure of the mycorrhizal fungi and the burden of metal stress at the scale of landscape remediation). Overall, the successful integration of any such processes into field-level applications hinges on identifying and then accounting for boundaries set by biogeochemical conditions of metal contaminated environments and the eco/physiological factors underpinning plant-soil interactions.

For further details, refer to:

• Audet P (2014) AM-fungi and metal phytoremediation: Eco-physiological complementarity in relation to environmental stress. In: Ahmad P (ed) Emerging technologies for the management of crops to biotic and abiotic stress, Vol. 2. Elsevier, New York. ISBN: 978-0-12-800875-1.

• Audet P, Charest C (2013) Assessing arbuscular mycorrhizal plant metal uptake and soil metal bioavailability among ‘dwarf’sunflowers in a stratified compartmental growth environment. Archives of Agronomy and Soil Science. 59: 533-548

• Audet P (2012) AM symbiosis and other plant-soil interactions in relation to environmental stress. In: Ahmad P and Prasad MNV (eds) Environmental adaptations and stress tolerance of plants in the era of climate change. Springer, New York. ISBN: 978-1-4614-0815-4.

• Audet P, Charest C (2009) Contribution of AM symbiosis to in vitro root metal uptake: From trace to toxic metal conditions. (Canadian Journal of) Botany. 87: 913-921.

• Audet P, Charest C (2008) Allocation plasticity & metal partitioning: meta analytical perspectives in phytoremediation. Environmental Pollution. 156: 290-296.

• Audet P, Charest C (2007) Dynamics of AM symbiosis in heavy metal phytoremediation: meta analytical and conceptual perspectives. Environmental Pollution. 147: 609-614.

• Audet P, Charest C (2007) Heavy metal phytoremediation from a meta-analytical perspective. Environmental Pollution. 147: 231-237.

• Audet P, Charest C (2006) Effects of AM colonization on 'wild tobacco' plants grown in Zn contaminated soils. Mycorrhiza. 16: 277-283.