A non-targeted metabolic profile in the fruits of both mulberry genotypes, collected at four post-flowering stages, was prepared based on the LC-MS/MS (Q Exactive, Thermo Scientific) procedure, as earlier described [11 (link)]. Briefly, ~2.5 mg fruit samples collected from DS and ZJ mulberry genotypes at the different stages mentioned above were sampled in 2 mL Eppendorf tubes containing pre-cooled metal beads and were then immediately stored in liquid nitrogen. The samples were first extracted with a ball mill at 30 Hz for 5 min; then, the extracted powder was dissolved in a 1.5-mL methanol/chloroform mixture and incubated at −20 °C for 5 h. Thereafter, the mixture was centrifuged at 2000× g and 4 °C for 10 min and then filtered with 0.43 μm organic phase medium (GE Healthcare, 6789-0404).
The metabolomic analysis was performed using the metabolon software (Durham, NC, USA). The sample components were identified by comparing the retention time and mass spectra with those of the reference metabolites (one by one). Regarding the identification of metabolic compounds in each sample, the mass spectra with the entries of the mass spectra libraries NIST02 and the Golm metabolome database were considered (http://csbdb.mpimp-golm.mpg.de/csbdb/gmd/gmd.html , accessed on 20 June 2020).
The metabolomic analysis was performed using the metabolon software (Durham, NC, USA). The sample components were identified by comparing the retention time and mass spectra with those of the reference metabolites (one by one). Regarding the identification of metabolic compounds in each sample, the mass spectra with the entries of the mass spectra libraries NIST02 and the Golm metabolome database were considered (