10.5061/DRYAD.4J0ZPC87G
Clausing, Simon
0000-0003-3640-5280
University of Göttingen
Polle, Andrea
0000-0001-8697-6394
University of Göttingen
Mycorrhizal phosphorus efficiencies and microbial competition drive root P
uptake
Dryad
dataset
2020
Deutsche Forschungsgemeinschaft
https://ror.org/018mejw64
Po362/22-2.
2020-05-18T00:00:00Z
2020-05-18T00:00:00Z
en
https://doi.org/10.3389/ffgc.2020.00054
59794 bytes
7
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Phosphorus (P) availability shows large differences among different soil
types, affecting P nutrition of forest trees. Chemical binding of P to
soil moieties affects partitioning of P between soil particles and
solution, affecting soluble P concentrations upon which plants, their
associated mycorrhizal symbionts, and microbes feed. The goal of this
study was to characterize root P uptake by mycorrhizal and non-mycorrhizal
root tips in competition with microbes in situ in the organic and mineral
layer of a P-rich and a P-poor forest. We used intact soil cores (0.2m
depth) from beech (Fagus sylvatica) forests to tracing the fate of 33P in
soil, plant and microbial fractions. We used the dilution of 33P in the
rhizosphere of each soil layer to estimate the enrichment with new P in
mycorrhizal and non-mycorrhizal root tips and root P uptake. In soil cores
from P-rich conditions, 25% and 75% of root P uptake occurred in the
organic and mineral layer, respectively, whereas in the P-poor forest, 60%
occurred in the organic and 40% in the mineral layer. Mycorrhizal P
efficiency, determined as enrichment of new P in mycorrhizal root tips,
differed between soil layers. Root P uptake was correlated with
mycorrhizal P efficiency and root tip abundance but not with root tip
abundance as a single factor. This finding underpins the importance of the
regulation of mycorrhizal P acquisition for root P supply. The composition
of mycorrhizal assemblages differed between forests but not between soil
layers. Therefore, differences in P efficiencies resulted from
physiological adjustments of the symbionts. Non-mycorrhizal root tips were
rare and exhibited lower enrichment with new P than mycorrhizal root tips.
Their contribution to root P supply was negligible. Microbes were strong
competitors for P in P-poor but not in P-rich soil. Understory roots were
present in the P-rich soil but did not compete for P. Our results uncover
regulation of mycorrhizal P efficiencies and highlight the complexity of
biotic and abiotic factors that govern P supply to trees in forest
ecosystems.
Collection of forest soil cores We collected ten intact soil cores in the
HP (27.6.2017) and the LP (19.6.2017) forest, respectively, using PVC
pipes of 120 mm diameter and a length of 200mm. Radioactive labeling and
harvest We labelled five soil cores per forest by addition of 1850 kBq of
H333PO4 (Hartmann Analytic GmbH, Braunschweig, Germany) in 40 ml of tap
water to each soil core. Analyses of root tips and mycorrhizal species
Fresh beech roots (10 fragments) were weighed and used to count the number
of root tips under a stereomicroscope (Leica M205 FA, Wetzlar, Germany).
Determination of total and soluble phosphorus in roots and soil Dry soil
and root samples were milled in a ball mill (Retsch MN 400, Haan, Germany)
to a fine powder. Determination of 33P by scintillation counting The
extracts of all soil, plant and root tip samples were used to measure 33P.
Table 1_Masses_P_33P Read_me1 contains information for Table 1
Table2_Morphotypes Read_me2 contains information for Table 2