Data analysis
Metabolite and lipid identification were based on retention indices and
total similarity scores found within MSDIAL, version 3.82 (Tsugawa et
al., 2015). Compounds were normalized relative to the internal standard.
An in-house custom library augmented with a library from Riken database
(http://prime.psc.riken.jp/Metabolomics_Software/MSDIAL/index.html) was
used for spectral matching of polar metabolites. To test metabolite
profile difference between treatments, metabolite abundance were
Hellinger-transformed (Ramette, 2007) and principal component analysis
(PCA) was performed with PC-ORD v6.08 (McCune & Mefford, 1999).
Data on plant biomass, root system architecture (primary seminal root
length, total root length, root surface area), ion content, lipid and
metabolite abundance were subjected to statistical analysis by one-way
ANOVA, using JMP software (SAS institute Inc., Cary, NC, USA).
Significance was defined as a probability level of P ≤0.05. Total
root length and root surface area were determined using WinRHIZO
software (Regent Instruments Inc., Ontario, CA).