LC-MS based metabolic fingerprinting of apricot pistils after self-compatible and self-incompatible pollinations.

KEY MESSAGE: LC-MS based metabolomics approach revealed that putative metabolites other than flavonoids may significantly contribute to the sexual compatibility reactions in Prunus armeniaca. Possible mechanisms on related microtubule-stabilizing effects are provided. Identification of metabolites playing crucial roles in sexual incompatibility reactions in apricot (Prunus armeniaca L.) was the aim of the study. Metabolic fingerprints of self-compatible and self-incompatible apricot pistils were created using liquid chromatography coupled to time-of-flight mass spectrometry followed by untargeted compound search. Multivariate statistical analysis revealed 15 significant differential compounds among the total of 4006 and 1005 aligned metabolites in positive and negative ion modes, respectively. Total explained variance of 89.55% in principal component analysis (PCA) indicated high quality of differential expression analysis. The statistical analysis showed significant differences between genotypes and pollination time as well, which demonstrated high performance of the metabolic fingerprinting and revealed the presence of metabolites with significant influence on the self-incompatibility reactions. Finally, polyketide-based macrolides similar to peloruside A and a hydroxy sphingosine derivative are suggested to be significant differential metabolites in the experiment. These results indicate a strategy of pollen tubes to protect microtubules and avoid growth arrest involved in sexual incompatibility reactions of apricot.

Metabolomic approach assisted high resolution LC-ESI-MS based identification of a xenobiotic derivative of fenhexamid produced by Lactobacillus casei.

Fenhexamid is a widely used fungicide with one of the highest maximum tolerance limits approved for fruits and vegetables. The goal of this study was to examine if fenhexamid is metabolized by a nontarget organism, a Lactobacillus species (Lactobacillus casei Shirota), a probiotic strain of the human gastrointestinal tract. The assignment of bacterial derivatives of the xenobiotic fenhexamid was substantially facilitated by a metabolomic software based approach optimized for the extraction of molecular features of chlorine-containing compounds from liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry data with an untargeted compound search algorithm. After validating the software with a set of seventeen chlorinated pesticides and manually verifying the result lists, eleven molecular features out of 4363 turned out to be bacterial derivatives of fenhexamid, revealing the O-glycosyl derivative as the most abundant one that arose from the fermentation medium of Lactobacillus casei Shirota in the presence of 100 µg/mL fenhexamid.