Mountain papaya ( Vasconcellea pubescens ) is a climacteric fruit that develops a strong and characteristic aroma during ripening. Esters are the main volatile compounds produced by the fruit, and most of them are dependent on ethylene. As esters are synthesized through alcohol acyltransferases (AAT), a full-length cDNA (VpAAT1) was isolated that displayed the characteristic motifs of most plant acyltransferases. The full-length cDNA sequence was cloned and expressed in yeasts, obtaining a functional enzyme with high AAT activity toward the formation of benzyl acetate. The transcript accumulation pattern provided by qPCR analysis showed that the VpAAT1 gene is expressed exclusively in fruit tissues and that a high level of transcripts is accumulated during ripening. The increase in VpAAT1 transcripts in fruit is coincident with the increase in AAT activity; transcript accumulation is induced by ethylene, and it is avoided by 1-methylcyclopropene (1-MCP) treatment. The data indicate that VpAAT1 is involved in aroma formation and that ethylene plays a major role in regulating its expression.
Fleshy fruits are characterized by having a developmentally and genetically controlled, highly intricate ripening process, leading to dramatic modifications in fruit size, texture, color, flavor, and aroma. Climacteric fruits such as tomato, pear, banana, and melon show a ripening-associated increase in respiration and ethylene production and these processes are well-documented. In contrast, the hormonal mechanism of fruit development and ripening in non-climacteric fruit, such as strawberry, grape, raspberry, and citrus, is not well characterized. However, recent studies have shown that non-climacteric fruit development and ripening, involves the coordinated action of different hormones, such as abscisic acid (ABA), auxin, gibberellins, ethylene, and others. In this review, we discuss and evaluate the recent research findings concerning the hormonal regulation of non-climacteric fruit development and ripening and their cross-talk by taking grape, strawberry, and raspberry as reference fruit species.
Fragaria chiloensis is characterized for having great aroma and flavor properties. Using headspace-SPME different volatile compounds were identified and quantified during development and ripening of the fruit. The headspace was dominated by esters, butyl acetate, ethyl acetate, ethyl butanoate and ethyl hexanoate being the most abundant in fully ripe fruit. As esters are important for aroma and synthesized through alcohol acyltransferases (AAT), a full-length cDNA (FcAAT1) was isolated from F. chiloensis fruit which displayed the three motifs characteristic of most AATs. As the production of esters increased during ripening, a clear increment in FcAAT1 transcripts was observed in fruit tissue. A good correlation was found between AAT activity and the total content of esters, especially with acetates and hexanoates. Aroma-related esters displayed during ripening the same production profile as AAT activity. Therefore it can be suggested that the FcAAT1 gene may have a significant role in ester production of F. chiloensis fruit.
In recent years, there has been an increasing interest in studying food and its derived ingredients that can provide beneficial effects for human health. These studies are helping to understand the bases of the ancestral use of several natural products, including native fruits as functional foods. As a result, the polyphenol profile and the antioxidant capacity of the extracts obtained from different Patagonian native berries have been described. This review aims to provide valuable information regarding fruit quality, its particular compound profile, and the feasibility of producing functional foods for human consumption to prevent disorders such as metabolic syndrome and cardiovascular diseases. We also discuss attempts concerning the domestication of these species and generating knowledge that strengthens their potential as traditional fruits in the food market and as a natural heritage for future generations. Finally, additional efforts are still necessary to fully understand the potential beneficial effects of the consumption of these berries on human health, the application of suitable technology for postharvest improvement, and the generation of successfully processed foods derived from Patagonian berries.
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