RESUMEN
Carotenoids are important lipophilic antioxidants in fruits. Apocarotenoids such as alpha-ionone and beta-ionone, which are breakdown products of carotenoids, are important for the flavor characteristics of raspberry fruit, and have also been suggested to have beneficial effects on human health. Raspberry is one of the few fruits where fruit ripening is accompanied by the massive production of apocarotenoids. In this paper, changes in levels of carotenoids and apocarotenoids during raspberry fruit ripening are described. In addition, the isolation and characterization of a gene encoding a carotenoid cleavage dioxygenase (CCD), which putatively mediates the degradation of carotenoids to apocarotenoids during raspberry fruit ripening, is reported. Such information helps us to better understand how these compounds are produced in plants and may also enable us to develop novel strategies for improved apocarotenoid production in fruits or indeed, alternative production systems.
Asunto(s)
Antioxidantes/metabolismo , Carotenoides/metabolismo , Frutas/metabolismo , Rosaceae/metabolismo , Antioxidantes/química , Carotenoides/química , Carotenoides/genética , Cromatografía Líquida de Alta Presión , Frutas/química , Frutas/genética , Expresión Génica/genética , Reacción en Cadena de la Polimerasa , Rosaceae/química , Rosaceae/genética , beta-Caroteno 15,15'-Monooxigenasa/genética , beta-Caroteno 15,15'-Monooxigenasa/metabolismoRESUMEN
Raspberry ketone is an important compound for the flavour industry. It is frequently used in products such as soft drinks, sweets, puddings and ice creams. The compound can be produced by organic synthesis. Demand for "natural" raspberry ketone is growing considerably. However, this product is extremely expensive. Consequently, there is a remaining desire to better understand how raspberry ketone is synthesized in vivo, and which genes and enzymes are involved. With this information we will then be in a better position to design alternative production strategies such as microbial fermentation. This article focuses on the identification and application of genes potentially linked to raspberry ketone synthesis. We have isolated candidate genes from both raspberry and other plants, and these have been introduced into bacterial and yeast expression systems. Conditions have been determined that result in significant levels of raspberry ketone, up to 5 mg/L. These results therefore lay a strong foundation for a potentially renewable source of "natural" flavour compounds making use of plant genes.