Nitrogen transfer within and between plants through Common Mycorrhizal Networks (CMNs)

He, X.H. and Critchley, C. and Bledsoe, C. (2003) Nitrogen transfer within and between plants through Common Mycorrhizal Networks (CMNs). Critical Reviews in Plant Sciences, 22 (6). pp. 531-567.

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Mycorrhizae play a critical role in nutrient capture from soils. Arbuscular mycorrhizae (AM) and ectomycorrhizae (EM) are the most important mycorrhizae in agricultural and natural ecosystems. AM and EM fungi use inorganic NH4+ and NO3-, and most EM fungi are capable of using organic nitrogen. The heavier stable isotope 15N is discriminated against during biogeochemical and biochemical processes. Differences in 15N (atom%) or δ15N (‰) provide nitrogen movement information in an experimental system. A range of 20 to 50% of one-way N-transfer has been observed from legumes to nonlegumes. Mycorrhizal fungal mycelia can extend from one plant's roots to another plant's roots to form common mycorrhizal networks (CMNs). Individual species, genera, even families of plants can be interconnected by CMNs. They are capable of facilitating nutrient uptake and flux. Nutrients such as carbon, nitrogen and phosphorus and other elements may then move via either AM or EM networks from plant to plant. Both 15N labeling and 15N natural abundance techniques have been employed to trace N movement between plants interconnected by AM or EM networks. Fine mesh (25∼45 μm) has been used to separate root systems and allow only hyphal penetration and linkages but no root contact between plants. In many studies, nitrogen from N2-fixing mycorrhizal plants transferred to non-N2-fixing mycorrhizal plants (one-way N-transfer). In a few studies, N is also transferred from non-N2-fixing mycorrhizal plants to N2-fixing mycorrhizal plants (two-way N-transfer). There is controversy about whether N-transfer is direct through CMNs, or indirect through the soil. The lack of convincing data underlines the need for creative, careful experimental manipulations. Nitrogen is crucial to productivity in most terrestrial ecosystems, and there are potential benefits of management in soil-plant systems to enhance N-transfer. Thus, two-way N-transfer warrants further investigation with many species and under field conditions

Item Type: Article
Author Affiliation: Department of Botany, The University of Queensland, St Lucia, Brisbane, Queensland 4072 Australia
Subjects: Crop Improvement
Crop Improvement > Biotechnology
Divisions: General
Depositing User: Syamala
Date Deposited: 19 Apr 2011 07:57
Last Modified: 19 Apr 2011 07:57
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