Full scan data analysis
The data files raw acquired with the Masslynx 4.1 software (Masslynx
4.1, Waters) were transformed into .cdf files with Databridge tool.
Chromatographic data files were processed using the software R
(http://www.r‐project.org/). The XCMS
algorithm (www.bioconductor.org; Smith et al., 2006) was used to obtain
the peak peaking, grouping, and signal corrections. Metabolite amounts
were analysed based on the normalized peak area units relative to the
dry weight. To test the metabolomic differences between treatments, a
nonparametric Kruskal–Wallis test (p < 0.01) was done.
Partial least square discriminant analysis and heat map analysis were
performed with the metaboAnalyst 4.0 (Chong et al., 2018). Adduct and
isotope correction, filtering, clustering, exact mass mapping and
metabolic pathway exploration was carried out with the packages MarVis
filter, MarVis cluster and MarVis pathway that are integrated in the
Marvis suit 2.0 (Kaever et al., 2014). Metabolite identification was
carried out based on exact mass accuracy and fragmentation spectra
matching with different online database. The database kegg
(https://www.genome.jp/kegg/) was used for exact mass identity and for
fragmentation spectrum analysis, the Massbank and the Metlin databases
were used (www.massbank.jp; www.masspec.scripps.edu).