Effects of bio-based coatings on the ripening and quality attributes of tomato (Solanum lycopersicum) fruits.

BACKGROUND: Postharvest conservation of tomatoes is a major current challenge for growers and traders. Edible coatings constitute a pertinent alternative to existing conservation methods. RESULTS: Control tomatoes were fully ripe 3 days after harvesting, whereas fruits dipped in solutions containing extracts from cocoa pods (T1), cocoa leaves (T2) or coffee hulls (T3) reached full ripeness 14 days after treatment (DAT). Fruits treated by dipping in a solution containing an extract from coffee leaves (T4) were fully ripe 21 DAT. The visual assessment was confirmed by alterations in the level of chlorophyll a. Treatments induced a significant inhibition of chlorophyll a breakdown, especially during the first week after their application, T4 being the most efficacious. Weight loss increased significantly throughout the experimental period and was accelerated by treatments. Some quality-related parameters of ripe tomato fruits were in most cases not significantly influenced by treatments. In a few cases, however, there were improvements in quality traits of ripe fruits. On 21 DAT, T4 induced significant increases in levels of ß-carotene and 6-methyl-3,5-heptadien-2-ol, whereas T2 led, especially, to higher levels of volatile compounds. CONCLUSION: Edible coatings based on extracts from coffee or cocoa leaves induced improvements in the shelf life and quality of tomato fruits. © 2018 Society of Chemical Industry.

Rhythmic changes in the levels of fatty acids in leaves of Phaseolus aureus seedlings did not tightly depend upon high/low temperatures cycles and alterations in chloroplast ultrastructure.

It is generally accepted that plastids play a major role in the synthesis of fatty acids. However, the degree of importance of the chloroplast integrity is not yet well established. In order to determine the effects of alterations in the chloroplast ultrastructure on this process Phaseolus aureus seedlings, species very sensitive to phase-shifts between light and temperature, were grown under control (12/12 h, 32/10 degrees C, light/dark) or inverse (12/12h, 10/32 degrees C, light/dark) conditions. Leaf sections were examined with an electron microscope and the fatty acid contents in the leaves and hypocotyls analyzed using a gas chromatograph. The electron microscopy of chloroplasts showed that unlike normal seedling leaves, there were few thylakoid membranes and no stacking of these membranes into grana occurred in the leaves of inverse seedlings. The levels of fatty acids in the leaves of normal seedlings (e.g., alpha-linolenic acid, 25 to 70 microg g(-1)) were always higher than those found in inverse seedling leaves (e.g., alpha-linolenic acid, 10 to 26 microg g(-1)). However, in leaves of both normal and inverse seedlings rhythmic fluctuations in the levels of fatty acids with 16 to 18 carbon atoms were observed. Furthermore, the fatty acid contents in hypocotyls of both types of seedlings were almost similar throughout the duration of the experiment. These results suggested that the high network density of thylakoid membranes and their stacking in places into grana are not prerequisites for the synthesis and/or conversion of fatty acids but would rather condition an optimal biogenesis rate and that light/dark cycles might be determinant factors in the induction of rhythmic fluctuations in fatty acid levels in plant leaves.

An oxygenase inhibitor study in Solanum lycopersicum combined with metabolite profiling analysis revealed a potent peroxygenase inactivator.

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 (IC(50) 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 C(18)-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.