Phosphorus deficiencies invoke optimal allocation of exoenzymes by ectomycorrhizas

• Published in: The ISME Journal Vol. 15; no. 5; pp. 1478 - 1489
• Main Authors: Meeds, Justin A., Marty Kranabetter, J., Zigg, Ieva, Dunn, Dave, Miros, François, Shipley, Paul, Jones, Melanie D.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2021; Nature Publishing Group
• Subjects: 631/158; 631/158/855; Biomedical and Life Sciences; Cellobiase; Ecology; Ectomycorrhizas; Evolutionary Biology; Forest floor; Fungi; Glucosaminidase; Glucosidase; Laccase; Life Sciences; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Nitrogen; NMR; Nuclear magnetic resonance; Orthophosphate; Phosphodiesterase; Phosphodiesters; Phosphorus; Podzolic soils; Soils; Xylosidase; β-Glucosidase
• ISSN: 1751-7362; 1751-7370
• DOI: 10.1038/s41396-020-00864-z

Ectomycorrhizal (EM) fungi can acquire phosphorus (P) through the production of extracellular hydrolytic enzymes (exoenzymes), but it is unclear as to the manner and extent native EM fungal communities respond to declining soil P availability. We examined the activity of six exoenzymes (xylosidase, N -acetyl glucosaminidase, β-glucosidase, acid phosphomonoesterase, acid phosphodiesterase [APD], laccase) from EM roots of Pseudotsuga menzesii across a soil podzolization gradient of coastal British Columbia. We found that APD activity increased fourfold in a curvilinear association with declining inorganic P. Exoenzyme activity was not related to organic P content, but at a finer resolution using 31 P-NMR, there was a strong positive relationship between APD activity and the ratio of phosphodiesters to orthophosphate of surface organic horizons (forest floors). Substantial increases (two- to fivefold) in most exoenzymes were aligned with declining foliar P concentrations of P . menzesii , but responses were statistically better in relation to foliar nitrogen (N):P ratios. EM fungal species with consistently high production of key exoenzymes were exclusive to Podzol plots. Phosphorus deficiencies in relation to N limitations may provide the best predictor of exoenzyme investment, reflecting an optimal allocation strategy for EM fungi. Resource constraints contribute to species turnover and the assembly of distinct, well-adapted EM fungal communities.