Flavonoid genes of pear (<Emphasis Type="Italic">Pyrus communis</Emphasis>) |
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Authors: | Thilo C Fischer Christian Gosch Judith Pfeiffer Heidrun Halbwirth Christian Halle Karl Stich Gert Forkmann |
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Institution: | 1.Lehrstuhl für Zierpflanzenbau und Gartenbauliche Pflanzenzüchtung, Department für Pflanzenwissenschaften,Technische Universit?t München Weihenstephan,Freising,Germany;2.Institut für Verfahrenstechnik, Umwelttechnik und Technische Biowissenschaften,Technische Universit?t Wien,Vienna,Austria |
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Abstract: | Pear (Pyrus sp.) is a major fruit crop of temperate regions with increasing extent of cultivation. Pear flavonoids contribute to its fruit
color, pathogen defense, and are health beneficial ingredients of the fruits. Comparative Southern analyses with apple (Malus x domestica) cDNAs showed comparable genomic organization of flavonoid genes of both related genera. A homology-based cloning approach
was used to obtain the cDNAs of most enzymes of the main flavonoid pathway of Pyrus: phenylalanine ammonia lyase, chalcone synthase, chalcone isomerase, flavanone 3β-hydroxylase, flavonol synthase, dihydroflavonol
4-reductase, leucoanthocyanidin reductase 1 and 2, anthocyanidin synthase, anthocyanidin reductase, and UDP-glucose : flavonoid
7-O-glucosyltransferase. The substrate specificities of the recombinant enzymes expressed in yeast were determined for physiological
and non-physiological substrates and found to be in general agreement with the characteristic pear flavonoid metabolite pattern
of mainly B-ring dihydroxylated anthocyanins, flavonols, catechins, and flavanones. Furthermore, significant differences in
substrate specificities and gene copy numbers in comparison to Malus were identified. Cloning of the cDNAs and studying the enzymes of the Pyrus flavonoid pathway is an essential task toward a comprehensive knowledge of Pyrus polyphenol metabolism. It also elucidates evolutionary patterns of flavonoid/polyphenol pathways in the Rosaceae, which allocate
several important crop plants. |
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Keywords: | Flavonoids Pear (Pyrus communis) Polyphenols Rosaceae |
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