10.5061/DRYAD.HT76HDRH5
Li, Hongbo
0000-0001-5273-1989
Chinese Academy of Agricultural Sciences
Wang, Xin-Xin
Hebei University
Zhang, Jiaqi
Hebei University
Wang, Hong
Hebei University
Rengel, Zed
University of Western Australia
Data for: Plasticity and co-variation of root traits govern phosphorus
acquisition among 20 wheat genotypes
Dryad
dataset
2021
adaptive strategy
Breeding
genotypic variation
plant plasticity
root exudation
root morphology
FOS: Agricultural sciences
2022-04-25T00:00:00Z
2022-04-25T00:00:00Z
en
https://doi.org/10.1111/oik.08606
OIK-08606
https://doi.org/10.5281/zenodo.6379114
35128 bytes
20
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Trait plasticity (variation of a trait under environmental variability or
gradients) and trait integration are both crucial for plant adaption to
environmental change. Variations in different suite of root traits such as
biomass allocation, morphology and physiology underlie diverse phosphorus
(P) acquisition strategies among plants. Yet, how the intraspecific
plasticity and integration of root traits influence plant adaptation to
different P supply remains obscure. To characterize diverse adaptive
strategies in relation to plant P acquisition, eight root traits were
assessed in 20 wheat (Triticum aestivum L.) genotypes grown in a culture
room with low and high P supply. High P supply increased shoot P
accumulation and biomass of all wheat genotypes. The shoot P accumulation
in genotypes with high P sensitivity (PS: calculated as shoot P content at
low P / shoot P content at high P supply) was higher with high P supply
and lower with low P supply compared with that in the genotypes with low
PS. The high-PS genotypes exhibited larger variation in root length,
root/shoot ratio and rhizosphere pH across P supplies than the low-PS
genotypes, suggesting an integrated response at the whole-plant level. At
low P supply, the high-PS genotypes had greater root length and specific
root length, but lower acid phosphatase activity than the low-PS
genotypes, which suggests contrasting P-acquisition strategies across the
genotypes. Strong co-variation of root traits occurred across low-PS
genotypes regardless of P supply; conversely, the high-PS genotypes only
exhibited strong trait integration at low P supply, whereas high P supply
sharply reduced root trait co-variation. Our findings suggest that P
stress may strengthen root trait integration in wheat plants, and that
both plasticity and integration of root traits drive plant adaptive
strategies and tolerance to P-deficiency stress.
Experimental set-up The experiment was set up as a randomized complete
block design, with two factors: (1) genotypes - 30 wheat genotypes, and
(2) P supplies - 0 and 200 mg P per kg soil (P was supplied as KH2PO4).
The experiment was carried out with four replicates. Pots within each
block were re-randomized weekly to further decrease effects of plant
location within blocks. Soil collection and wheat genotypes A calcareous
silt loamy, low-P soil was collected from Dongdianzhuang, Baoding
(114°30′E, 39°05′N), China. Soil properties were as follows: pH 7.40 (1:5
soil:water ratio), soil bulk density 1.45 g cm-3, total N 1.26 g kg-1,
Olsen-P 5.50 mg kg-1, and total K 20.45 g kg-1. The soil was sieved (2 mm)
and mixed thoroughly. The sieved soil was then used to fill plastic pots
of 11 cm in height and 18 cm in diameter (1 kg dry soil per pot). Thirty
wheat genotypes released from 1977 to 2016 were selected initially for
this study (Table S1). They are the main winter wheat genotypes planted in
Hebei Province during the relevant periods. Their P sensitivity ranged
from 0.070 to 0.175, with a mean of 0.121. The classes of high/low P
sensitivity (P sensitivity was calculated as shoot P content at low P /
shoot P content at high P supply) genotype groups were constructed by
finding a median value of P sensitivity and creating the medium-PS
interval as median ± S.E of the genotype effect. Genotypes with data
falling above or below that medium interval were classed as high-PS or
low-PS genotypes, respectively (Malik et al. 2016; Rengel and Graham
1995). To better compare how different genotypes responded to low and high
P supply, we selected 10 high-PS and 10 low-PS genotypes for further
analyses without considering the medium group (Table S1). Wheat seeds were
surface sterilized (30 min in 30% v/v H2O2 solution), rinsed, and
subsequently germinated on the wet filter paper at 25 °C for 24 h in the
dark. Six uniformly germinated seeds were sown into each pot. After one
week, the seedlings were thinned to four plants per pot. During the whole
experimental period, soil moisture was kept at 18–20% (w/w, i.e., 70% of
water holding capacity) as determined gravimetrically by weighing the pots
every 2 days and adding de-ionized water when necessary. In a culture
room, temperatures ranged from 10 (night) to 15 °C (day), and the average
photosynthetically active radiation was 33.6 W m-2. This was accomplished
by applying 14 hours of LED light from 6:00 am to 8:00 pm. Relative air
humidity was kept at 40–50%. The nutrient solutions were added to the soil
as basal fertilizers at the following rates (mg kg-1): 1687 (NH4)2SO4, 335
K2SO4, 126 CaCl2, 43 MgSO4·7H2O, 2.0 CuSO4·5H2O, 5.8 EDTA-FeNa, and 10
ZnSO4·7H2O. To achieve the same soil K condition between the two P
treatments, 252 mg K as K2SO4 was supplied to soil in the low P treatment.
The pot experiment was conducted from December 2018 to January 2019 at the
eastern campus of Hebei Agricultural University (115°49′E, 38°85′N),
Baoding, China. Harvest and measurements Plants were harvested at 37 DAS
and divided into shoots and roots. Shoots were cut at the soil surface and
oven-dried at 72 °C for 48 h, weighed, and ground to fine powder. Shoot P
concentration was determined by the standard vanado-molybdate method
(Murphy and Riley 1962) after digestion in a H2SO4-H2O2 mixture at 360 °C
for 2 h. We measured eight root traits in three categories (Bardgett et
al. 2014; Wang et al. 2020a): 1) three whole-root system traits: root
biomass, root/shoot ratio and root length; 2) three root morphological
traits: root diameter, RTD and SRL; and 3) two root physiological traits:
pH of the rhizosphere soil and phosphatase activity in the rhizosphere. A
full description of every root trait is provided below. Roots with soil
adhered were shaken gently to remove bulk soil, and then the rhizosphere
soil was collected by brushing it off roots. Rhizosphere soil was stored
at 4 °C, and subsequently used to measure pH within 3 days. After sampling
rhizosphere soil, all visible roots were sieved out. Root samples were
cleaned using de-ionized water and frozen at -20 °C prior to measurement
of root morphological parameters. Cleaned root samples were dispersed in
water in a transparent tray (30×20×3 cm) and scanned with an EPSON scanner
at a resolution of 400 dpi (Epson Expression 1600 pro, Model EU-35,
Japan). The root traits such as root length and root diameter were
determined by analysis of images using WinRHIZO Pro software (2009b;
Regent Instruments Inc, Quebec, Canada) software. Scanned root images were
shown in Figure S1. SRL (m g-1) was assessed as the ratio of root length
over dry root weight. Specific root volume (cm3 g-1) was assessed as the
ratio of root volume over dry root weight. After root samples were
scanned, the roots were also oven-dried at 70 °C for 3 days and weighed as
root biomass, and then root/shoot biomass ratio was calculated. In
addition, we calculated RTD as root dry weight over root volume, assuming
roots were perfect cylinders (Ostonen et al. 2007). Phosphatase activity
in the rhizosphere was measured according to (Alvey et al. 2001) using
p-nitrophenylphosphate (p-NPP). The whole root systems with tightly
adhering rhizosphere soil were transferred into 200-mL vials containing a
measured amount of 0.2 mM CaCl2 solution depending on root volume
(Veneklaas et al. 2003). The pH value of Na-acetate buffer (200 mM) was
adjusted to the average pH values (7.4) of the rhizosphere soil. The
rhizosphere soil in the CaCl2 suspension was separated by centrifugation
for 10 min at 12,000 × g, dried at 60 °C and then weighed. The
concentration of p-NPP in the supernatant was measured
spectrophotometrically at 405 nm.