Ectomycorrhizal symbiosis: Difference between revisions
mNo edit summary |
mNo edit summary |
||
| Line 1: | Line 1: | ||
==Introduction== | ==Introduction== | ||
An ectomycorrhiza is a mutualistic relationship occurring between fungi and the root systems of certain plants. Unlike other mycorrhizae, ectomycorrhizae aid their hosts by creating networks of hyphae surrounding roots. These networks mediate the exchange of nutrients to plants and carbon to fungi.<br> <ref>[https://link.springer.com/content/pdf/10.1007/s00572-009-0274-x.pdf Tedersoo, L., May, T and Smith, M. "Ectomycorrhizal lifestyle in fungi: global diversity, distribution, and evolution of phylogenetic lineages" 2009. Mycorrhiza 20:217–263.]</ref> | An ectomycorrhiza is a mutualistic relationship occurring between fungi and the root systems of certain plants. Unlike other mycorrhizae, ectomycorrhizae aid their hosts by creating networks of hyphae surrounding roots. These networks mediate the exchange of nutrients to plants and carbon to fungi.<br> <ref>[https://link.springer.com/content/pdf/10.1007/s00572-009-0274-x.pdf Tedersoo, L., May, T and Smith, M. "Ectomycorrhizal lifestyle in fungi: global diversity, distribution, and evolution of phylogenetic lineages" 2009. Mycorrhiza 20:217–263.]</ref> | ||
==Nutritional Exchange== | ==Nutritional Exchange== | ||
Ectomycorrhizal (ECM) fungi have can uptake and provide a host with a wide range of macronutrients such as potassium, phosphorus, sulfur, and micronutrients such as iron, zinc, and copper. However, they are most recognized for the transport of nitrogen (N) as it is the main growth-limiting factor in many forest ecosystems. The first step of nutritional exchange between ECM fungi and a plant host is for encoded N transporters to uptake and utilize nitrate and ammonium from the soil. The utilized N can be acquired from either inorganic or organic N sources. Ammonium can be taken up from inorganic sources and is the most preferred source by ECM fungi as it does not require energy to be used on chemical reduction. <ref>[https://doi.org/10.3389/fpls.2019.01658 Stuart, Emiko K., and Krista L. Plett. "Digging deeper: in search of the mechanisms of carbon and nitrogen exchange in ectomycorrhizal symbioses." Frontiers in plant science 10 (2020): 1658.]</ref> Three main ammonium transporters have been identified in several fungal ECM species: AMT1, AMT2, and AMT3. The former two are high-affinity transporters, meaning their expression is upregulated most in conditions of low ammonium. <ref> [https://doi.org/10.1046/j.1365-2958.2003.03303.x Javelle, Arnaud, Mélanie Morel, Blanca‐Rosa Rodríguez‐Pastrana, Bernard Botton, Bruno André, Anne‐Marie Marini, Annick Brun, and Michel Chalot. "Molecular characterization, function and regulation of ammonium transporters (Amt) and ammonium‐metabolizing enzymes (GS, NADP‐GDH) in the ectomycorrhizal fungus Hebeloma cylindrosporum." Molecular microbiology 47, no. 2 (2003): 411-430.] </ref> Nitrate can also be uptaken by ECM fungi and requires the regulation of nitrate transporters, such as LbNRT2, and nitrate reductase enzymes. <ref> [https://doi.org/10.1111/j.1758-2229.2009.00111.x Kemppainen, Minna J., Maria C. Alvarez Crespo, and Alejandro G. Pardo. "fHANT‐AC genes of the ectomycorrhizal fungus Laccaria bicolor are not repressed by l‐glutamine allowing simultaneous utilization of nitrate and organic nitrogen sources." Environmental microbiology reports 2, no. 4 (2010): 541-553.] </ref> In the presence of ammonium, the nitrate uptake pathway is downregulated due to the fungal preference for ammonium. The oxidative decomposition mechanisms inherited by ECM fungi from their saprotrophic ancestors allow for organic N sources to be used as well. Peptidase secretion is used to reduce proteins from the soil into smaller peptide products. <ref>[https://doi.org/10.3389/fpls.2019.01658 Stuart, Emiko K., and Krista L. Plett. "Digging deeper: in search of the mechanisms of carbon and nitrogen exchange in ectomycorrhizal symbioses." Frontiers in plant science 10 (2020): 1658.]</ref> <br> | Ectomycorrhizal (ECM) fungi have can uptake and provide a host with a wide range of macronutrients such as potassium, phosphorus, sulfur, and micronutrients such as iron, zinc, and copper. However, they are most recognized for the transport of nitrogen (N) as it is the main growth-limiting factor in many forest ecosystems. The first step of nutritional exchange between ECM fungi and a plant host is for encoded N transporters to uptake and utilize nitrate and ammonium from the soil. The utilized N can be acquired from either inorganic or organic N sources. Ammonium can be taken up from inorganic sources and is the most preferred source by ECM fungi as it does not require energy to be used on chemical reduction. <ref>[https://doi.org/10.3389/fpls.2019.01658 Stuart, Emiko K., and Krista L. Plett. "Digging deeper: in search of the mechanisms of carbon and nitrogen exchange in ectomycorrhizal symbioses." Frontiers in plant science 10 (2020): 1658.]</ref> Three main ammonium transporters have been identified in several fungal ECM species: AMT1, AMT2, and AMT3. The former two are high-affinity transporters, meaning their expression is upregulated most in conditions of low ammonium. <ref> [https://doi.org/10.1046/j.1365-2958.2003.03303.x Javelle, Arnaud, Mélanie Morel, Blanca‐Rosa Rodríguez‐Pastrana, Bernard Botton, Bruno André, Anne‐Marie Marini, Annick Brun, and Michel Chalot. "Molecular characterization, function and regulation of ammonium transporters (Amt) and ammonium‐metabolizing enzymes (GS, NADP‐GDH) in the ectomycorrhizal fungus Hebeloma cylindrosporum." Molecular microbiology 47, no. 2 (2003): 411-430.] </ref> Nitrate can also be uptaken by ECM fungi and requires the regulation of nitrate transporters, such as LbNRT2, and nitrate reductase enzymes. <ref> [https://doi.org/10.1111/j.1758-2229.2009.00111.x Kemppainen, Minna J., Maria C. Alvarez Crespo, and Alejandro G. Pardo. "fHANT‐AC genes of the ectomycorrhizal fungus Laccaria bicolor are not repressed by l‐glutamine allowing simultaneous utilization of nitrate and organic nitrogen sources." Environmental microbiology reports 2, no. 4 (2010): 541-553.] </ref> In the presence of ammonium, the nitrate uptake pathway is downregulated due to the fungal preference for ammonium. The oxidative decomposition mechanisms inherited by ECM fungi from their saprotrophic ancestors allow for organic N sources to be used as well. Peptidase secretion is used to reduce proteins from the soil into smaller peptide products. <ref>[https://doi.org/10.3389/fpls.2019.01658 Stuart, Emiko K., and Krista L. Plett. "Digging deeper: in search of the mechanisms of carbon and nitrogen exchange in ectomycorrhizal symbioses." Frontiers in plant science 10 (2020): 1658.]</ref> <br> | ||
Revision as of 16:47, 18 November 2021
Introduction
An ectomycorrhiza is a mutualistic relationship occurring between fungi and the root systems of certain plants. Unlike other mycorrhizae, ectomycorrhizae aid their hosts by creating networks of hyphae surrounding roots. These networks mediate the exchange of nutrients to plants and carbon to fungi.
[1]
Nutritional Exchange
Ectomycorrhizal (ECM) fungi have can uptake and provide a host with a wide range of macronutrients such as potassium, phosphorus, sulfur, and micronutrients such as iron, zinc, and copper. However, they are most recognized for the transport of nitrogen (N) as it is the main growth-limiting factor in many forest ecosystems. The first step of nutritional exchange between ECM fungi and a plant host is for encoded N transporters to uptake and utilize nitrate and ammonium from the soil. The utilized N can be acquired from either inorganic or organic N sources. Ammonium can be taken up from inorganic sources and is the most preferred source by ECM fungi as it does not require energy to be used on chemical reduction. [2] Three main ammonium transporters have been identified in several fungal ECM species: AMT1, AMT2, and AMT3. The former two are high-affinity transporters, meaning their expression is upregulated most in conditions of low ammonium. [3] Nitrate can also be uptaken by ECM fungi and requires the regulation of nitrate transporters, such as LbNRT2, and nitrate reductase enzymes. [4] In the presence of ammonium, the nitrate uptake pathway is downregulated due to the fungal preference for ammonium. The oxidative decomposition mechanisms inherited by ECM fungi from their saprotrophic ancestors allow for organic N sources to be used as well. Peptidase secretion is used to reduce proteins from the soil into smaller peptide products. [5]
Genetic Upregulation
Include some current research, with a second image.
Conclusion
Overall text length (all text sections) should be at least 1,000 words (before counting references), with at least 2 images.
Include at least 5 references under References section.
References
- ↑ Tedersoo, L., May, T and Smith, M. "Ectomycorrhizal lifestyle in fungi: global diversity, distribution, and evolution of phylogenetic lineages" 2009. Mycorrhiza 20:217–263.
- ↑ Stuart, Emiko K., and Krista L. Plett. "Digging deeper: in search of the mechanisms of carbon and nitrogen exchange in ectomycorrhizal symbioses." Frontiers in plant science 10 (2020): 1658.
- ↑ Javelle, Arnaud, Mélanie Morel, Blanca‐Rosa Rodríguez‐Pastrana, Bernard Botton, Bruno André, Anne‐Marie Marini, Annick Brun, and Michel Chalot. "Molecular characterization, function and regulation of ammonium transporters (Amt) and ammonium‐metabolizing enzymes (GS, NADP‐GDH) in the ectomycorrhizal fungus Hebeloma cylindrosporum." Molecular microbiology 47, no. 2 (2003): 411-430.
- ↑ Kemppainen, Minna J., Maria C. Alvarez Crespo, and Alejandro G. Pardo. "fHANT‐AC genes of the ectomycorrhizal fungus Laccaria bicolor are not repressed by l‐glutamine allowing simultaneous utilization of nitrate and organic nitrogen sources." Environmental microbiology reports 2, no. 4 (2010): 541-553.
- ↑ Stuart, Emiko K., and Krista L. Plett. "Digging deeper: in search of the mechanisms of carbon and nitrogen exchange in ectomycorrhizal symbioses." Frontiers in plant science 10 (2020): 1658.
Edited by Ronan Daly, student of Joan Slonczewski for BIOL 116 Information in Living Systems, 2021, Kenyon College.
