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Abscisic acid (ABA) is a key hormone in non-climacteric Fragaria spp, regulating multiple physiological processes throughout fruit ripening. Its concentration increases during ripening, and it promotes fruit (receptacle) development. However, its metabolism in the fruit is largely unknown. We analyzed the concentrations of ABA and its catabolites at different developmental stages of strawberry ripening in diploid and octoploid genotypes and identified two functional ABA-glucosyltransferases (FvUGT71A49 and FvUGT73AC3) and two regiospecific ABA-8'-hydroxylases (FaCYP707A4a and FaCYP707A1/3). ABA-glucose ester content increased during ripening in diploid F. vesca varieties but decreased in octoploid F.× ananassa. Dihydrophaseic acid content increased throughout ripening in all analyzed receptacles, while 7'-hydroxy-ABA and neo-phaseic acid did not show significant changes during ripening. In the studied F. vesca varieties, the receptacle seems to be the main tissue for ABA metabolism, as the concentration of ABA and its metabolites in the receptacle was generally 100 times higher than in achenes. The accumulation patterns of ABA catabolites and transcriptomic data from the literature show that all strawberry fruits produce and metabolize considerable amounts of the plant hormone ABA during ripening, which is therefore a conserved process, but also illustrate the diversity of this metabolic pathway which is species, variety, and tissue dependent. [ABSTRACT FROM AUTHOR]

Plant genomes contain a vast number of oxygenase genes, but only very few have been functionally characterized. To devise an alternative method for the detection of novel oxygenase-catalysed reactions the effects of the cytochrome P450 oxygenase inhibitors 1-aminobenzotriazole (ABT) and tetcyclacis (TET) have been examined by metabolite profiling analysis in tomato fruit (Solanum lycopersicum). Treatment with TET resulted in significant increases in the levels of certain flavonoids, whereas ABT strongly inhibited their formation during fruit ripening. Injections of buffered solutions of ABT into tomato fruits led rather to an accumulation of 9,12,13-trihydroxy-10(E)-octadecenoic acid probably due to retarded metabolism of the hydroxylated acid, while TET completely repressed its formation. Peroxygenase, a hydroperoxide-dependent hydroxylase involved in the formation of the trihydroxy fatty acid, is strongly inhibited by TET (IC50 2.6 μM) as was demonstrated by studies with the recombinant tomato enzyme expressed in yeast. The data show that ABT and TET affect oxygenases differently in tomato fruit and reveal that these enzymes catalyse distinct reactions in different metabolic pathways, among which C18-trihydroxy fatty acid and flavonoid metabolism involve novel oxygenase-catalysed reactions. The method is suitable to identify potential substrates and products of ripening-related, putative oxygenases and can support functional analyses of recombinant enzymes. [ABSTRACT FROM PUBLISHER]