Genetic, Molecular, and Genomic Approaches to Improve the Value of Plant Foods and Feeds

Galili, Gad; Galili, Shmuel; Lewinsohn, Efraim; Tadmor, Yaakov

doi:10.1080/0735-260291044232

Cited by 105 publications

(51 citation statements)

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“…The availability of RhAAT1 and similar AAT genes that encode enzymes for the formation of fragrances will allow a better understanding of the factors that influence and limit the biogeneration of scent compounds. This information can be used to generate crops with improved or modified fragrance using the modern biotechnological tools available (Galili et al, 2002).…”

Section: Resultsmentioning

confidence: 99%

Volatile Ester Formation in Roses. Identification of an Acetyl-Coenzyme A. Geraniol/Citronellol Acetyltransferase in Developing Rose Petals

et al. 2003

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The aroma of roses (Rosa hybrida) is due to more than 400 volatile compounds including terpenes, esters, and phenolic derivatives. 2-Phenylethyl acetate, cis-3-hexenyl acetate, geranyl acetate, and citronellyl acetate were identified as the main volatile esters emitted by the flowers of the scented rose var. "Fragrant Cloud." Cell-free extracts of petals acetylated several alcohols, utilizing acetyl-coenzyme A, to produce the corresponding acetate esters. Screening for genes similar to known plant alcohol acetyltransferases in a rose expressed sequence tag database yielded a cDNA (RhAAT1) encoding a protein with high similarity to several members of the BAHD family of acyltransferases. This cDNA was functionally expressed in Escherichia coli, and its gene product displayed acetyl-coenzyme A:geraniol acetyltransferase enzymatic activity in vitro. The RhAAT1 protein accepted other alcohols such as citronellol and 1-octanol as substrates, but 2-phenylethyl alcohol and cis-3-hexen-1-ol were poor substrates, suggesting that additional acetyltransferases are present in rose petals. The RhAAT1 protein is a polypeptide of 458 amino acids, with a calculated molecular mass of 51.8 kD, pI of 5.45, and is active as a monomer. The RhAAT1 gene was expressed exclusively in floral tissue with maximum transcript levels occurring at stage 4 of flower development, where scent emission is at its peak.Roses (Rosa hybrida) are grown as garden plants, for the cut-flower industry, and as a source of natural fragrances. Many modern cut-flower rose cultivars were selected for long vase life, flower shape, and color. Intensive breeding has also generated garden cultivars that have an intense "rose" scent. More than 400 different volatile compounds have been identified in rose scent, and these compounds have been classified into several chemical groups including hydrocarbons, alcohols, esters, aromatic ethers, and "others" (aldehydes such as geranial and nonanal, rose oxide, and norisoprenes such as ␤-ionone; Flament et al., 1993;Weiss, 1997).Volatile esters such as geranyl acetate and 2-phenylethyl acetate are important contributors to the aroma of roses and many other flowers (Knudsen and Tollsten, 1993). Volatile esters also contribute to the unique aroma of fruits such as banana (Musa acuminata), apple (Malus domestica), melon (Cucumis melo), strawberry (Fragaria ananassa), and spice plants such as lavender (Lavandula officinalis; Croteau and Karp, 1991;Ueda et al., 1992). Despite the knowledge of the contribution of volatile acetate esters to the aroma of roses, including the demonstration of the circadian emission of some major volatile acetate esters by flowers of the rose var. "Honesty" (Helsper et al., 1998), little is known about the mechanisms by which these compounds are formed in roses.Acetate esters in plants are normally generated as a result of the action of alcohol acetyltransferase (AAT) enzymes that transfer the acetyl moiety from acetylCoA to an alcoholic substrate ( Fig. 1; Harada et al., 1985;Fellman and Mattheis, 19...

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Section: Resultsmentioning

confidence: 99%

Volatile Ester Formation in Roses. Identification of an Acetyl-Coenzyme A. Geraniol/Citronellol Acetyltransferase in Developing Rose Petals

et al. 2003

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“…Indeed, plants are cultivated by humans not only for their nutritional value and medicinal properties, but also for their unique aromas. While fruit avors and aromas are major factors in fruit quality, these traits are often genetically complex and dif®cult to score and quantify (Galili et al, 2002), making them dif®cult targets for classical breeding. The current public interest in healthy and¯avorful plant products (Galili et al, 2002), combined with the emerging potential for plant metabolic engineering (Broun and Somerville, 2001), emphasize the importance of elucidating the biosynthetic pathways, enzymes, genes, and regulatory mechanisms involved in fruit¯avor and aroma formation.…”

Section: Introductionmentioning

confidence: 99%

Citrus fruit flavor and aroma biosynthesis: isolation, functional characterization, and developmental regulation of Cstps1, a key gene in the production of the sesquiterpene aroma compound valencene

Sharon-Asa¹,

Shalit²,

Frydman³

et al. 2003

The Plant Journal

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192

125

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SummaryCitrus fruits possess unique aromas rarely found in other fruit species. While fruit flavor is composed of complex combinations of soluble and volatile compounds, several low‐abundance sesquiterpenes, such as valencene, nootkatone, alpha‐sinensal, and beta‐sinensal, stand out in citrus as important flavor and aroma compounds. The profile of terpenoid volatiles in various citrus species and their importance as aroma compounds have been studied in detail, but much is still lacking in our understanding of the physiological, biochemical, and genetic regulation of their production. Here, we report on the isolation, functional expression, and developmental regulation of Cstps1, a sesquiterpene synthase‐encoding gene, involved in citrus aroma formation. The recombinant enzyme encoded by Cstps1 was shown to convert farnesyl diphosphate to a single sesquiterpene product identified as valencene by gas chromatography–mass spectrometry (GC–MS). Phylogenetic analysis of plant terpene synthase genes localized Cstps1 to the group of angiosperm sesquiterpene synthases. Within this group, Cstps1 belongs to a subgroup of citrus sesquiterpene synthases. Cstps1 was found to be developmentally regulated: transcript was found to accumulate only towards fruit maturation, corresponding well with the timing of valencene accumulation in fruit. Although citrus fruits are non‐climacteric, valencene accumulation and Cstps1 expression were found to be responsive to ethylene, providing further evidence for the role of ethylene in the final stages of citrus fruit ripening. Isolation of the gene encoding valencene synthase provides a tool for an in‐depth study of the regulation of aroma compound biosynthesis in citrus and for metabolic engineering for fruit flavor characteristics.

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“…Several food crops are now being developed with enhanced vitamin E, vitamin C, modified starch and amino acid profiles (11,24,42). Potato is the most important non-cereal food crop for human consumption and, therefore, the need to improve its nutritional quality cannot be overemphasized.…”

Section: Improvement Of Crop Nutritional Qualitiesmentioning

confidence: 99%

Plant Biotechnological Approaches for the Production and Commercialization of Transgenic Crops

Khan

Liu

2009

Biotechnology & Biotechnological Equipment

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Genetic, Molecular, and Genomic Approaches to Improve the Value of Plant Foods and Feeds

Cited by 105 publications

References 0 publications

Volatile Ester Formation in Roses. Identification of an Acetyl-Coenzyme A. Geraniol/Citronellol Acetyltransferase in Developing Rose Petals

Volatile Ester Formation in Roses. Identification of an Acetyl-Coenzyme A. Geraniol/Citronellol Acetyltransferase in Developing Rose Petals

Citrus fruit flavor and aroma biosynthesis: isolation, functional characterization, and developmental regulation of Cstps1, a key gene in the production of the sesquiterpene aroma compound valencene

Plant Biotechnological Approaches for the Production and Commercialization of Transgenic Crops

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