Table 2.
Modification of low molecular weight organic acid (LMWOA) exudates from trees by different ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) fungi.
| Tree species | ECM or AM | Mycorrhizal symbiont | ECM/AM effect on LMWOA exudation (vs. non ECM/AM roots) | Methodology | References |
|---|---|---|---|---|---|
| Scots pine | ECM | Paxillus involutus | ↑ oxalic acid, formic acid | 9-month-old inoculated seedlings were planted in sterilized soil collected from an E-horizon, and placed in climate controlled growth room. LMWOA were collected via suction from soil column and indentified using capillary zone electrophoresis | van Hees et al., 2005 |
| Suillus granulatus | ↑ citric acid | ||||
| Norway spruce | ECM | Paxillus involutus | ↑ malonic acid | ||
| Scots pine | ECM | Suillus variegatus | ↑oxalic acid | 9–12-week-old inoculated seedlings were grown in petri dishes containing glass beads with a growth solution. LMWOA were analyzed using HPLC analysis | Ahonen-Jonnarth et al., 2000 |
| Rhizopogon roseolus | ↑ oxalic acid | ||||
| Paxillus involutus | ↑oxalic acid, malonic acid | ||||
| Scots Pine (under elevated CO2) | ECM | Sullius variegates | ↑oxalic acid | 16-week-old inoculated seedlings were grown in petri dishes containing peat:vermiculite substrate with a growth solution. LMWOA were analyzed using HPLC analysis | Johansson et al., 2009 |
| Sulliusbovinus | |||||
| Paxillusinvolutus | |||||
| Rhizopogon roseolus | |||||
| Hebelomavelutipes | ↑citric, fumaric, formic, malonic acid | ||||
| Piloderma croceum | |||||
| Scots pine | ECM | Hebeloma longicaudum | ↓malonic acid | 21-week-old inoculated seedlings were grown on glass beads or sand with a growth solution. LMWOA were indentified using capillary zone electrophoresus | van Schöll et al., 2006 |
| Paxillus involutus | ↑oxalic | ||||
| Piloderma croceum | |||||
| White spruce | ECM | Not identified | ↑ malonic, oxalic, gluconic, succinic, protocatechuic acid | Soil collected in situ around trees that were 20–35 cm diameter at breast height. LMWOA were indentified using capillary zone electrophoresis | Tuason and Arocena, 2009 |
| Subalpine fir | ECM | Not identified | ↑ malonic, oxalic, glutaric, isocitric acid | ||
| Norway spruce | ECM | Paxillus involutus | ↑ Malate, citric | 9-month-old inoculated seedlings were planted in a soil-sand column system. LMWOA were collected using suction from soil column and analyzed using capillary zone electrophoresus | van Hees et al., 2003 |
| Scots pine | ECM | Hebeloma crustuliniforme | ↑oxalic, citric, propionic acid | 16-week-old inoculated seedlings were grown in a sand culture system. LMWOA were collected via suction from soil column and analyzed using capillary zone electrophoresis. | van Hees et al., 2006a |
| ↑oxalic acid, ferrocrocin | 16-week-old inoculated seedlings were grown in aseptic multi-compartment dishes containing sterile nutrient agar with stock nutrient solution. LMWOA were analyzed using capillary zone electrophoresis | van Hees et al., 2006b | |||
| Norway spruce | ECM | Laccaria bicolor | ↑oxalic acid | 8-week-old inoculated seedlings were grown in glass bead mesocosms with growth medium. LMWOA were analyzed using HPLC analysis | Eldhuset et al., 2007 |
| Japanese red pine | ECM | Pisolithus tinctorius | ↑citric acid | 4-month-old inoculated seedlings were grown in perlite in pots. LMWOA were analyzed using an electroconductivity detection method | Tahara et al., 2005 |
| Scots pine | ECM | Amantia muscaria | ↑LMWOA exudation, individual OA’s varied depending on N addition and elevated CO2 | 4-week-old Inoculated seedlings were grown in petri dishes containing vermiculite and a growth medium. LMWOA were analyzed using capillary zone electrophoresis | Fransson and Johansson, 2010. |
| Hebeloma velutipes | |||||
| Piloderma fallax | |||||
| Suillus variegatus | |||||
| Scots pine | ECM | Hebeloma velutipes, | ↑LMWOA exudation, especially oxalic acid | 16-week-old inoculated seedlings were grown in petri dishes containing peat:vermiculate and growth medium. LMWOA were analyzed using capillary zone electrophoresis | Johansson et al., 2008 |
| P. involutus, | |||||
| Piloderma byssinum, | |||||
| R. roseolus, | |||||
| S. bovinus | |||||
| S. variegatus | |||||
| Tulip poplar | AM | Acaulospora | - | 5-month-old seedlings were grown in fungal inoculated sand. Roots were washed for organic acid profiles. LMWOA were indentified using ion chromatography | Klugh and Cumming, 2007 |
| morrowiae | - | ||||
| Glomus | ↑ malate, citric acid | ||||
| claroideumG. clarum | - | ||||
| Paraglomus brasilianum | - |
↑, increase; -, no change; ↓, decrease; n/a, information not available.