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.

Variabilité des caractéristiques physiques des mangues cultivées au Tchad : caractérisation de la diversité fonctionnelle 12933 montrent que la variabilité des paramètres étudiés résulterait d'une diversité fonctionnelle des mangues cultivées au Tchad. Mots clés : Variétés de mangues, caractères physiques, diversité fonctionnelle, Tchad et régions de culture ABSTRACT Variability of physical characteristics of mangoes cultivated in Chad: characterization of the functional diversity Objective: Chad produces more than 14 varieties of mangoes; however, their physicals characteristics are little known. The aim of the study was to determine the physical characteristics of these varieties of mangoes in order to contribute to their popularization and valorization. Methodology and results: Physical data were collected from each mango fruit in a sample of 15 ripe fruits of one variety harvested from three mango trees in an orchard. All fruits were harvested from 12 orchards in the four study regions. This study showed that Davis haden, Smith, Eldon, Kent and Coeur de Boeuf mango varieties cultivated in Chad and particularly in the region of Logone Occidental had the best physical parameters including mass, volume, index of caliber, the mass of the pulp and the pulp yield. On the other hand, the local varieties (Bangui, Kassaï and Mangotine) had the most modest parameters except the variety Maïduguri, which is classified among the medium varieties group with José Tchad, Julie Kassawa, Keitt, Palmer and Valencia, but nevertheless possessed the best commercial quality (pulp proportion: 83.26 ± 2.36%). Local varieties had higher firmness (2.33 ± 0.38 to 2.46 ± 0.33) than improved varieties (2.11 ± 0.29 to 2.39 ± 0.23). All these varieties of mangoes grown in Chad were elongated and had at ripe stage a specific weight nearly to 1 (0.99 ± 0.01 to 1.12 ± 1.02). In all these varieties of mango, a perfect positive correlation (r = 1) was found between the mass of the mango and the mass of the pulp. Conclusions and applications of the results: This study showed that there is a great variability of morphological and phycical characteristics between varieties and that they are milieu-dependent. The improved varieties were clearly distinguishable from local varieties by the importance of morphological and physical parameters. The results obtained would allow an appreciation of the adaptive potential of mango varieties and provide the necessary informations to the various actors in the mango sector in order to rationalize the choice of mango varieties. They could in particular allow the sorting of mature and ripe fruits because the ripe fruits have a specific weight nearly to unit, therefore floatable on water. Finally, these results indicated that the variability of parameters studied could be a result of a funtional diversity of mango varieties cultivated in Chad.

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 β‐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

Objective: Little is known about physiological functions of flavonoids, specifically in the course of maturation and ripening of fruits. Spatiotemporal changes in the levels of flavonoids were investigated in the present study with focus on possible functional differentiation of individual compounds as related to the maturation or ripening of tomato fruits. Methodology and results: The contents of flavonoids in different tissues of tomato fruits at increasing maturation and ripening stages were determined using high performance liquid chromatography -mass spectrometry. The levels of eriodictyol, kaempferol-glc-rhamnose, naringenin, naringenin-chalcone-hexose and quercetin-glc-rhamnose remained almost constant in the mesocarp and endocarp. The contents of eriodictyol, dicaffeoylquinic acid, naringenin and naringenin-chalcone-hexose significantly (P<0.05) increased in the epicarp from ripening stage 1 onwards. The concentration of dicaffeoyquinic acid increased significantly (P<0.05) in both the mesocarp and endocarp of tomato fruits from ripening stage 1 onwards. Gradual increases in the levels of caffeic-acid-hexose and caffeoylquinic acid in the epicarp and endocarp of tomatoes were observed. The level of kaempferol-glc-rhamnose decreased gradually in the epicarp. The content of quercetin-glc-rhamnose was always higher in the epicarp than in the mesocarp and endocarp. The results obtained indicated increases in the endogenous levels of some flavonoids in the epicarp (especially naringenin) with the onset of the ripening. There was also a gradual decrease and increase in the levels of respectively kaempferol-glc-rhamnose in the epicarp and caffeic-acid-hexose in the endocarp. Thus, an increase in the level of naringenin in the epicarp could be considered as physiological index for the ripening whereas high levels of kaempferol-glc-rhamnose in the epicarp and caffeic-acidhexose in the endocarp could serve as characteristic traits for respectively immature and red-ripe state of tomato fruits. On the whole, the results point to specific roles of individual flavonoids as some might be involved in the regulation of either the maturation or ripening of tomato fruits whereas others might functionally be needed throughout both processes, and that there would be a specialization of tissues in the synthesis of specific types of flavonoids. Conclusions and application findings:The degree of accumulation of flavonoids in tomato varied according to the nature of the tissue, and the maturation and ripening stages. It is hypothesized that an increase in Journal of Applied Biosciences 84:7674-7681 ISSN 1997-5902 Aghofack-Nguemezi and Schwab. J. Appl. Biosci. Differential accumulation of flavonoids by tomato (Solanum lycopersicum) fruits tissues during maturation and ripening 7683 the contents of naringenin and caffeic-acid-hexose may be part of natural mechanisms by which ripe tomato fruits prevent the over ripening when they are still attached to the mother plant. Consequently, the enhancement of the levels of these...

Notwithstanding the important roles of calcium and magnesium ions in plant growth and development, the use of fertilizers containing them is not yet a common agricultural practice inThe green-life of fruits produced by these two tomato varieties that received T 1 was respectively 10 and 6 days longer than that of control fruits. T 2 prolonged the shelf-life of fruits from those varieties by 4 and 12 days respectively. On the whole, Rio Grande and Rio de Grenier plant were the tomato varieties whose health, growth, development, yield and fruit quality parameters were the most positively affected by treatments with fertilizers containing calcium oder magnesium. Roma tomato plants were affected to a lesser extent by these treatments. These results could be interpreted in terms of a temporal shift in the resistance of tomato plants to P. infestans and S. lycopersici on the one hand and A. solani and F. fulva on the other hand and also in terms of similarities of responses of closely related tomato varieties to fertilizers.